/***************************************************************************
 *   Copyright (c) 2008 Jürgen Riegel <juergen.riegel@web.de>              *
 *                                                                         *
 *   This file is part of the FreeCAD CAx development system.              *
 *                                                                         *
 *   This library is free software; you can redistribute it and/or         *
 *   modify it under the terms of the GNU Library General Public           *
 *   License as published by the Free Software Foundation; either          *
 *   version 2 of the License, or (at your option) any later version.      *
 *                                                                         *
 *   This library  is distributed in the hope that it will be useful,      *
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
 *   GNU Library General Public License for more details.                  *
 *                                                                         *
 *   You should have received a copy of the GNU Library General Public     *
 *   License along with this library; see the file COPYING.LIB. If not,    *
 *   write to the Free Software Foundation, Inc., 59 Temple Place,         *
 *   Suite 330, Boston, MA  02111-1307, USA                                *
 *                                                                         *
 ***************************************************************************/

#include "PreCompiled.h"
#ifndef _PreComp_
# include <cmath>
# include <vector>

# include <BRep_Tool.hxx>
# include <BRepAdaptor_Curve.hxx>
# include <BRepAdaptor_Surface.hxx>
# include <BRepBuilderAPI_MakeEdge.hxx>
# include <BRepBuilderAPI_MakeFace.hxx>
# include <BRepOffsetAPI_NormalProjection.hxx>
# include <GC_MakeCircle.hxx>
# include <Geom_BSplineCurve.hxx>
# include <Geom_Circle.hxx>
# include <Geom_Ellipse.hxx>
# include <Geom_Hyperbola.hxx>
# include <Geom_Line.hxx>
# include <Geom_Parabola.hxx>
# include <Geom_Plane.hxx>
# include <Geom_TrimmedCurve.hxx>
# include <GeomAPI_ProjectPointOnSurf.hxx>
# include <GeomConvert_BSplineCurveKnotSplitting.hxx>
# include <gp_Ax3.hxx>
# include <gp_Circ.hxx>
# include <gp_Elips.hxx>
# include <gp_Hypr.hxx>
# include <gp_Parab.hxx>
# include <gp_Pln.hxx>
# include <Standard_Version.hxx>
# include <TColStd_Array1OfInteger.hxx>
# include <TopExp_Explorer.hxx>
# include <TopoDS.hxx>
# include <TopoDS_Edge.hxx>
# include <TopoDS_Face.hxx>
# include <TopoDS_Shape.hxx>
#endif

#include <App/Application.h>
#include <App/Document.h>
#include <App/Expression.h>
#include <App/ExpressionParser.h>
#include <App/FeaturePythonPyImp.h>
#include <App/ObjectIdentifier.h>
#include <App/OriginFeature.h>
#include <App/Part.h>
#include <Base/Console.h>
#include <Base/Reader.h>
#include <Base/Tools.h>
#include <Base/Vector3D.h>
#include <Base/Writer.h>
#include <Mod/Part/App/BodyBase.h>
#include <Mod/Part/App/DatumFeature.h>
#include <Mod/Part/App/GeometryMigrationExtension.h>

#include "SketchObject.h"
#include "SketchObjectPy.h"
#include "SolverGeometryExtension.h"


#undef DEBUG
//#define DEBUG

using namespace Sketcher;
using namespace Base;
namespace bp = boost::placeholders;

FC_LOG_LEVEL_INIT("Sketch",true,true)

PROPERTY_SOURCE(Sketcher::SketchObject, Part::Part2DObject)

SketchObject::SketchObject()
{
    ADD_PROPERTY_TYPE(Geometry,        (nullptr)  ,"Sketch",(App::PropertyType)(App::Prop_None),"Sketch geometry");
    ADD_PROPERTY_TYPE(Constraints,     (nullptr)  ,"Sketch",(App::PropertyType)(App::Prop_None),"Sketch constraints");
    ADD_PROPERTY_TYPE(ExternalGeometry,(nullptr,nullptr),"Sketch",(App::PropertyType)(App::Prop_None),"Sketch external geometry");
    ADD_PROPERTY_TYPE(FullyConstrained, (false),"Sketch",(App::PropertyType)(App::Prop_Output|App::Prop_ReadOnly |App::Prop_Hidden),"Sketch is fully constrained");

    Geometry.setOrderRelevant(true);

    allowOtherBody = true;
    allowUnaligned = true;

    for (std::vector<Part::Geometry *>::iterator it=ExternalGeo.begin(); it != ExternalGeo.end(); ++it)
        if (*it) delete *it;
    ExternalGeo.clear();
    auto HLine = GeometryTypedFacade<Part::GeomLineSegment>::getTypedFacade();
    auto VLine = GeometryTypedFacade<Part::GeomLineSegment>::getTypedFacade();
    HLine->getTypedGeometry()->setPoints(Base::Vector3d(0,0,0),Base::Vector3d(1,0,0));
    VLine->getTypedGeometry()->setPoints(Base::Vector3d(0,0,0),Base::Vector3d(0,1,0));
    HLine->setConstruction(true);
    VLine->setConstruction(true);
    ExternalGeo.push_back(HLine->getGeometry());
    ExternalGeo.push_back(VLine->getGeometry());
    HLine->setOwner(false); // we have transferred the ownership to ExternalGeo
    VLine->setOwner(false); // we have transferred the ownership to ExternalGeo
    rebuildVertexIndex();

    lastDoF=0;
    lastHasConflict=false;
    lastHasRedundancies=false;
    lastHasPartialRedundancies=false;
    lastHasMalformedConstraints=false;
    lastSolverStatus=0;
    lastSolveTime=0;

    solverNeedsUpdate=false;

    noRecomputes=false;

    ExpressionEngine.setValidator(boost::bind(&Sketcher::SketchObject::validateExpression, this, bp::_1, bp::_2));

    constraintsRemovedConn = Constraints.signalConstraintsRemoved.connect(boost::bind(&Sketcher::SketchObject::constraintsRemoved, this, bp::_1));
    constraintsRenamedConn = Constraints.signalConstraintsRenamed.connect(boost::bind(&Sketcher::SketchObject::constraintsRenamed, this, bp::_1));

    analyser = new SketchAnalysis(this);

    internaltransaction=false;
    managedoperation=false;
}

SketchObject::~SketchObject()
{
    for (std::vector<Part::Geometry *>::iterator it=ExternalGeo.begin(); it != ExternalGeo.end(); ++it)
        if (*it) delete *it;
    ExternalGeo.clear();

    delete analyser;
}

short SketchObject::mustExecute() const
{
    if (Geometry.isTouched())
        return 1;
    if (Constraints.isTouched())
        return 1;
    if (ExternalGeometry.isTouched())
        return 1;
    return Part2DObject::mustExecute();
}

App::DocumentObjectExecReturn *SketchObject::execute()
{
    try {
        App::DocumentObjectExecReturn* rtn = Part2DObject::execute();//to positionBySupport
        if(rtn!=App::DocumentObject::StdReturn)
            //error
            return rtn;
    }
    catch (const Base::Exception& e) {
        return new App::DocumentObjectExecReturn(e.what());
    }

    // setup and diagnose the sketch
    try {
        rebuildExternalGeometry();
        Constraints.acceptGeometry(getCompleteGeometry());
    }
    catch (const Base::Exception& e) {
        Base::Console().Error("%s\nClear constraints to external geometry\n", e.what());
        // we cannot trust the constraints of external geometries, so remove them
        delConstraintsToExternal();
    }

    // This includes a regular solve including full geometry update, except when an error
    // ensues
    int err = this->solve(true);

    if (err == -4) { // over-constrained sketch
        std::string msg="Over-constrained sketch\n";
        appendConflictMsg(lastConflicting, msg);
        return new App::DocumentObjectExecReturn(msg.c_str(),this);
    }
    else if (err == -3) { // conflicting constraints
        std::string msg="Sketch with conflicting constraints\n";
        appendConflictMsg(lastConflicting, msg);
        return new App::DocumentObjectExecReturn(msg.c_str(),this);
    }
    else if (err == -2) { // redundant constraints
        std::string msg="Sketch with redundant constraints\n";
        appendRedundantMsg(lastRedundant, msg);
        return new App::DocumentObjectExecReturn(msg.c_str(),this);
    }
    else if (err == -5) {
        std::string msg="Sketch with malformed constraints\n";
        appendMalformedConstraintsMsg(lastMalformedConstraints, msg);
        return new App::DocumentObjectExecReturn(msg.c_str(),this);
    }
    else if (err == -1) { // Solver failed
        return new App::DocumentObjectExecReturn("Solving the sketch failed",this);
    }

    // this is not necessary for sketch representation in edit mode, unless we want to trigger an update of
    // the objects that depend on this sketch (like pads)
    Shape.setValue(solvedSketch.toShape());

    return App::DocumentObject::StdReturn;
}

int SketchObject::hasConflicts() const
{
    if (lastDoF < 0) // over-constrained sketch
        return -2;
    if (solvedSketch.hasConflicts()) // conflicting constraints
        return -1;

    return 0;
}

void SketchObject::retrieveSolverDiagnostics()
{
    lastHasConflict = solvedSketch.hasConflicts();
    lastHasRedundancies = solvedSketch.hasRedundancies();
    lastHasPartialRedundancies = solvedSketch.hasPartialRedundancies();
    lastHasMalformedConstraints = solvedSketch.hasMalformedConstraints();
    lastConflicting=solvedSketch.getConflicting();
    lastRedundant=solvedSketch.getRedundant();
    lastPartiallyRedundant=solvedSketch.getPartiallyRedundant();
    lastMalformedConstraints=solvedSketch.getMalformedConstraints();
}

int SketchObject::solve(bool updateGeoAfterSolving/*=true*/)
{
    Base::StateLocker lock(managedoperation, true); // no need to check input data validity as this is an sketchobject managed operation.

    // Reset the initial movement in case of a dragging operation was ongoing on the solver.
    solvedSketch.resetInitMove();

    // if updateGeoAfterSolving=false, the solver information is updated, but the Sketch is nothing
    // updated. It is useful to avoid triggering an OnChange when the goeometry did not change but
    // the solver needs to be updated.

    // We should have an updated Sketcher (sketchobject) geometry or this solve() should not have happened
    // therefore we update our sketch solver geometry with the SketchObject one.
    //
    // set up a sketch (including dofs counting and diagnosing of conflicts)
    lastDoF = solvedSketch.setUpSketch(getCompleteGeometry(), Constraints.getValues(),
                                  getExternalGeometryCount());

    // At this point we have the solver information about conflicting/redundant/over-constrained, but the sketch is NOT solved.
    // Some examples:
    // Redundant: a vertical line, a horizontal line and an angle constraint of 90 degrees between the two lines
    // Conflicting: a 80 degrees angle between a vertical line and another line, then adding a horizontal constraint to that other line
    // OverConstrained: a conflicting constraint when all other DoF are already constrained (it has more constraints than parameters and the extra constraints are not redundant)

    solverNeedsUpdate=false;

    retrieveSolverDiagnostics();

    lastSolveTime=0.0;

    lastSolverStatus=GCS::Failed; // Failure is default for notifying the user unless otherwise proven

    int err=0;

    // redundancy is a lower priority problem than conflict/over-constraint/solver error
    // we set it here because we are indeed going to solve, as we can. However, we still want to
    // provide the right error code.
    if (lastHasRedundancies) { // redundant constraints
        err = -2;
    }

    if (lastDoF < 0) { // over-constrained sketch
        err = -4;
    }
    else if (lastHasConflict) { // conflicting constraints
        // The situation is exactly the same as in the over-constrained situation.
        err = -3;
    }
    else if (lastHasMalformedConstraints) {
        err = -5;
    }
    else {
        lastSolverStatus=solvedSketch.solve();
        if (lastSolverStatus != 0){ // solving
            err = -1;
        }
    }

    if(lastHasMalformedConstraints) {
        Base::Console().Error(this->getFullLabel(), QT_TRANSLATE_NOOP("Notifications","The Sketch has malformed constraints!") "\n");
    }

    if(lastHasPartialRedundancies) {
        Base::Console().Warning(this->getFullLabel(), QT_TRANSLATE_NOOP("Notifications","The Sketch has partially redundant constraints!") "\n");
    }

    lastSolveTime=solvedSketch.getSolveTime();

    // In uncommon situations, the analysis of QR decomposition leads to full rank, but the result does not converge.
    // We avoid marking a sketch as fully constrained when no convergence is achieved.
    if(err == 0) {
        FullyConstrained.setValue(lastDoF == 0);
    }
    
    if (err == 0 && updateGeoAfterSolving) {
        // set the newly solved geometry
        std::vector<Part::Geometry *> geomlist = solvedSketch.extractGeometry();
        Geometry.setValues(geomlist);
        for (std::vector<Part::Geometry *>::iterator it = geomlist.begin(); it != geomlist.end(); ++it)
            if (*it) delete *it;
    }
    else if(err <0) {
        // if solver failed, invalid constraints were likely added before solving
        // (see solve in addConstraint), so solver information is definitely invalid.
        this->Constraints.touch();
    }

    return err;
}

int SketchObject::setDatum(int ConstrId, double Datum)
{
    Base::StateLocker lock(managedoperation, true); // no need to check input data validity as this is an sketchobject managed operation.

    // set the changed value for the constraint
    if (this->Constraints.hasInvalidGeometry())
        return -6;
    const std::vector<Constraint *> &vals = this->Constraints.getValues();
    if (ConstrId < 0 || ConstrId >= int(vals.size()))
        return -1;
    ConstraintType type = vals[ConstrId]->Type;
    if (!vals[ConstrId]->isDimensional() &&
        type != Tangent && //for tangent, value==0 is autodecide, value==Pi/2 is external and value==-Pi/2 is internal
        type != Perpendicular)
        return -1;

    if ((type == Distance || type == Radius || type == Diameter || type == Weight) && Datum <= 0)
        return (Datum == 0) ? -5 : -4;

    // copy the list
    std::vector<Constraint *> newVals(vals);
    double oldDatum = newVals[ConstrId]->getValue();
    newVals[ConstrId] = newVals[ConstrId]->clone();
    newVals[ConstrId]->setValue(Datum);

    this->Constraints.setValues(std::move(newVals));

    int err = solve();

    if (err)
        this->Constraints.getValues()[ConstrId]->setValue(oldDatum); // newVals is a shell now

    return err;
}

int SketchObject::setDriving(int ConstrId, bool isdriving)
{
    Base::StateLocker lock(managedoperation, true); // no need to check input data validity as this is an sketchobject managed operation.

    const std::vector<Constraint *> &vals = this->Constraints.getValues();

    int ret = testDrivingChange(ConstrId, isdriving);

    if(ret < 0)
        return ret;

    // copy the list
    std::vector<Constraint *> newVals(vals);
    newVals[ConstrId] = newVals[ConstrId]->clone();
    newVals[ConstrId]->isDriving = isdriving;

    this->Constraints.setValues(std::move(newVals));

    if (!isdriving)
        setExpression(Constraints.createPath(ConstrId), std::shared_ptr<App::Expression>());

    if(noRecomputes) // if we do not have a recompute, the sketch must be solved to update the DoF of the solver
        solve();

    return 0;
}

int SketchObject::getDriving(int ConstrId, bool &isdriving)
{
    const std::vector<Constraint *> &vals = this->Constraints.getValues();

    if (ConstrId < 0 || ConstrId >= int(vals.size()))
        return -1;

    if (!vals[ConstrId]->isDimensional())
        return -1;

    isdriving=vals[ConstrId]->isDriving;
    return 0;
}

int SketchObject::testDrivingChange(int ConstrId, bool isdriving)
{
    const std::vector<Constraint *> &vals = this->Constraints.getValues();

    if (ConstrId < 0 || ConstrId >= int(vals.size()))
        return -1;

    if (!vals[ConstrId]->isDimensional())
        return -2;

    if (!(vals[ConstrId]->First>=0 || vals[ConstrId]->Second>=0 || vals[ConstrId]->Third>=0) && isdriving)
        return -3; // a constraint that does not have at least one element as not-external-geometry can never be driving.

    return 0;
}

int SketchObject::setActive(int ConstrId, bool isactive)
{
    Base::StateLocker lock(managedoperation, true); // no need to check input data validity as this is an sketchobject managed operation.

    const std::vector<Constraint *> &vals = this->Constraints.getValues();

    if (ConstrId < 0 || ConstrId >= int(vals.size()))
        return -1;

    // copy the list
    std::vector<Constraint *> newVals(vals);
    // clone the changed Constraint
    Constraint *constNew = vals[ConstrId]->clone();
    constNew->isActive = isactive;
    newVals[ConstrId] = constNew;
    this->Constraints.setValues(std::move(newVals));

    if(noRecomputes) // if we do not have a recompute, the sketch must be solved to update the DoF of the solver
        solve();

    return 0;
}

int SketchObject::getActive(int ConstrId, bool &isactive)
{
    const std::vector<Constraint *> &vals = this->Constraints.getValues();

    if (ConstrId < 0 || ConstrId >= int(vals.size()))
        return -1;

    isactive = vals[ConstrId]->isActive;

    return 0;
}

int SketchObject::toggleActive(int ConstrId)
{
    Base::StateLocker lock(managedoperation, true); // no need to check input data validity as this is an sketchobject managed operation.

    const std::vector<Constraint *> &vals = this->Constraints.getValues();

    if (ConstrId < 0 || ConstrId >= int(vals.size()))
        return -1;

    // copy the list
    std::vector<Constraint *> newVals(vals);
    // clone the changed Constraint
    Constraint *constNew = vals[ConstrId]->clone();
    constNew->isActive = !constNew->isActive;
    newVals[ConstrId] = constNew;
    this->Constraints.setValues(std::move(newVals));

    if(noRecomputes) // if we do not have a recompute, the sketch must be solved to update the DoF of the solver
        solve();

    return 0;
}


/// Make all dimensionals Driving/non-Driving
int SketchObject::setDatumsDriving(bool isdriving)
{
    Base::StateLocker lock(managedoperation, true); // no need to check input data validity as this is an sketchobject managed operation.

    const std::vector<Constraint *> &vals = this->Constraints.getValues();
    std::vector<Constraint *> newVals(vals);

    for(size_t i=0; i<newVals.size(); i++) {
        if (!testDrivingChange(i, isdriving)) {
            newVals[i] = newVals[i]->clone();
            newVals[i]->isDriving = isdriving;
        }
    }

    this->Constraints.setValues(std::move(newVals));

    const std::vector<Constraint *> &uvals = this->Constraints.getValues(); // newVals is a shell now

    for (size_t i = 0; i < uvals.size(); i++) {
        if (!isdriving && uvals[i]->isDimensional())
            setExpression(Constraints.createPath(i), std::shared_ptr<App::Expression>());
    }

    if (noRecomputes) // if we do not have a recompute, the sketch must be solved to update the DoF of the solver
        solve();

    return 0;
}

int SketchObject::moveDatumsToEnd()
{
    Base::StateLocker lock(managedoperation, true); // no need to check input data validity as this is an sketchobject managed operation.

    const std::vector<Constraint *> &vals = this->Constraints.getValues();

    std::vector<Constraint *> copy(vals);
    std::vector<Constraint *> newVals(vals.size());

    int addindex= copy.size()-1;

    // add the dimensionals at the end
    for (int i= copy.size()-1 ; i >= 0; i--) {
        if(copy[i]->isDimensional()) {
            newVals[addindex] = copy[i];
            addindex--;
        }
    }

    // add the non-dimensionals
    for (int i = copy.size()-1; i >= 0; i--) {
        if(!copy[i]->isDimensional()) {
            newVals[addindex] = copy[i];
            addindex--;
        }
    }

    this->Constraints.setValues(std::move(newVals));

    if (noRecomputes) // if we do not have a recompute, the sketch must be solved to update the DoF of the solver
        solve();

    return 0;
}

int SketchObject::setVirtualSpace(int ConstrId, bool isinvirtualspace)
{
    Base::StateLocker lock(managedoperation, true); // no need to check input data validity as this is an sketchobject managed operation.

    const std::vector<Constraint *> &vals = this->Constraints.getValues();

    if (ConstrId < 0 || ConstrId >= int(vals.size()))
        return -1;

    // copy the list
    std::vector<Constraint *> newVals(vals);

    // clone the changed Constraint
    Constraint *constNew = vals[ConstrId]->clone();
    constNew->isInVirtualSpace = isinvirtualspace;
    newVals[ConstrId] = constNew;

    this->Constraints.setValues(std::move(newVals));

    return 0;
}

int SketchObject::setVirtualSpace(std::vector<int> constrIds, bool isinvirtualspace)
{
    Base::StateLocker lock(managedoperation, true); // no need to check input data validity as this is an sketchobject managed operation.

    if (constrIds.empty())
        return 0;

    std::sort(constrIds.begin(),constrIds.end());

    const std::vector< Constraint * > &vals = this->Constraints.getValues();

    if (constrIds.front() < 0 || constrIds.back() >= int(vals.size()))
        return -1;

    std::vector< Constraint * > newVals(vals);

    for(auto cid : constrIds) {
        // clone the changed Constraint
        if(vals[cid]->isInVirtualSpace != isinvirtualspace) {
            Constraint *constNew = vals[cid]->clone();
            constNew->isInVirtualSpace = isinvirtualspace;
            newVals[cid] = constNew;
        }
    }

    this->Constraints.setValues(std::move(newVals));

    return 0;
}



int SketchObject::getVirtualSpace(int ConstrId, bool &isinvirtualspace) const
{
    const std::vector<Constraint *> &vals = this->Constraints.getValues();

    if (ConstrId < 0 || ConstrId >= int(vals.size()))
        return -1;

    isinvirtualspace=vals[ConstrId]->isInVirtualSpace;
    return 0;
}

int SketchObject::toggleVirtualSpace(int ConstrId)
{
    Base::StateLocker lock(managedoperation, true); // no need to check input data validity as this is an sketchobject managed operation.

    const std::vector<Constraint *> &vals = this->Constraints.getValues();

    if (ConstrId < 0 || ConstrId >= int(vals.size()))
        return -1;

    // copy the list
    std::vector<Constraint *> newVals(vals);

    // clone the changed Constraint
    Constraint *constNew = vals[ConstrId]->clone();
    constNew->isInVirtualSpace = !constNew->isInVirtualSpace;
    newVals[ConstrId] = constNew;

    this->Constraints.setValues(std::move(newVals));

    return 0;
}


int SketchObject::setUpSketch()
{
    lastDoF = solvedSketch.setUpSketch(getCompleteGeometry(), Constraints.getValues(),
                                       getExternalGeometryCount());

    retrieveSolverDiagnostics();

    if(lastHasRedundancies || lastDoF < 0 || lastHasConflict || lastHasMalformedConstraints || lastHasPartialRedundancies)
        Constraints.touch();

    return lastDoF;
}

int SketchObject::diagnoseAdditionalConstraints(std::vector<Sketcher::Constraint *> additionalconstraints)
{
    auto objectconstraints = Constraints.getValues();

    std::vector<Sketcher::Constraint *> allconstraints;
    allconstraints.reserve(objectconstraints.size()+additionalconstraints.size());

    std::copy(objectconstraints.begin(), objectconstraints.end(), back_inserter(allconstraints));
    std::copy(additionalconstraints.begin(), additionalconstraints.end(), back_inserter(allconstraints));

    lastDoF = solvedSketch.setUpSketch(getCompleteGeometry(), allconstraints,
                                       getExternalGeometryCount());

    retrieveSolverDiagnostics();

    return lastDoF;

}

int SketchObject::movePoint(int GeoId, PointPos PosId, const Base::Vector3d& toPoint, bool relative, bool updateGeoBeforeMoving)
{
    Base::StateLocker lock(managedoperation, true); // no need to check input data validity as this is an sketchobject managed operation.

    // if we are moving a point at SketchObject level, we need to start from a solved sketch
    // if we have conflicts we can forget about moving. However, there is the possibility that we
    // need to do programmatically moves of new geometry that has not been solved yet and that because
    // they were programmatically generated won't generate a conflict. This is the case of Fillet for
    // example. This is why exceptionally, it may be required to update the sketch geometry to that of
    // of SketchObject upon moving. => use updateGeometry parameter = true then


    if(updateGeoBeforeMoving || solverNeedsUpdate) {
        lastDoF = solvedSketch.setUpSketch(getCompleteGeometry(), Constraints.getValues(),
                                    getExternalGeometryCount());

        retrieveSolverDiagnostics();

        solverNeedsUpdate=false;
    }

    if (lastDoF < 0) // over-constrained sketch
        return -1;
    if (lastHasConflict) // conflicting constraints
        return -1;

    // move the point and solve
    lastSolverStatus = solvedSketch.movePoint(GeoId, PosId, toPoint, relative);

    // moving the point can not result in a conflict that we did not have
    // or a redundancy that we did not have before, or a change of DoF

    if (lastSolverStatus == 0) {
        std::vector<Part::Geometry *> geomlist = solvedSketch.extractGeometry();
        Geometry.setValues(geomlist);
        //Constraints.acceptGeometry(getCompleteGeometry());
        for (std::vector<Part::Geometry *>::iterator it=geomlist.begin(); it != geomlist.end(); ++it) {
            if (*it) delete *it;
        }
    }

    solvedSketch.resetInitMove(); // reset solver point moving mechanism

    return lastSolverStatus;
}

Base::Vector3d SketchObject::getPoint(int GeoId, PointPos PosId) const
{
    if(!(GeoId == H_Axis || GeoId == V_Axis
         || (GeoId <= getHighestCurveIndex() && GeoId >= -getExternalGeometryCount()) ))
        throw Base::ValueError("SketchObject::getPoint. Invalid GeoId was supplied.");
    const Part::Geometry *geo = getGeometry(GeoId);
    if (geo->getTypeId() == Part::GeomPoint::getClassTypeId()) {
        const Part::GeomPoint *p = static_cast<const Part::GeomPoint*>(geo);
        if (PosId == PointPos::start || PosId == PointPos::mid || PosId == PointPos::end)
            return p->getPoint();
    } else if (geo->getTypeId() == Part::GeomLineSegment::getClassTypeId()) {
        const Part::GeomLineSegment *lineSeg = static_cast<const Part::GeomLineSegment*>(geo);
        if (PosId == PointPos::start)
            return lineSeg->getStartPoint();
        else if (PosId == PointPos::end)
            return lineSeg->getEndPoint();
    } else if (geo->getTypeId() == Part::GeomCircle::getClassTypeId()) {
        const Part::GeomCircle *circle = static_cast<const Part::GeomCircle*>(geo);
        if (PosId == PointPos::mid)
            return circle->getCenter();
    } else if (geo->getTypeId() == Part::GeomEllipse::getClassTypeId()) {
        const Part::GeomEllipse *ellipse = static_cast<const Part::GeomEllipse*>(geo);
        if (PosId == PointPos::mid)
            return ellipse->getCenter();
    } else if (geo->getTypeId() == Part::GeomArcOfCircle::getClassTypeId()) {
        const Part::GeomArcOfCircle *aoc = static_cast<const Part::GeomArcOfCircle*>(geo);
        if (PosId == PointPos::start)
            return aoc->getStartPoint(/*emulateCCW=*/true);
        else if (PosId == PointPos::end)
            return aoc->getEndPoint(/*emulateCCW=*/true);
        else if (PosId == PointPos::mid)
            return aoc->getCenter();
    } else if (geo->getTypeId() == Part::GeomArcOfEllipse::getClassTypeId()) {
        const Part::GeomArcOfEllipse *aoc = static_cast<const Part::GeomArcOfEllipse*>(geo);
        if (PosId == PointPos::start)
            return aoc->getStartPoint(/*emulateCCW=*/true);
        else if (PosId == PointPos::end)
            return aoc->getEndPoint(/*emulateCCW=*/true);
        else if (PosId == PointPos::mid)
            return aoc->getCenter();
    } else if (geo->getTypeId() == Part::GeomArcOfHyperbola::getClassTypeId()) {
        const Part::GeomArcOfHyperbola *aoh = static_cast<const Part::GeomArcOfHyperbola*>(geo);
        if (PosId == PointPos::start)
            return aoh->getStartPoint();
        else if (PosId == PointPos::end)
            return aoh->getEndPoint();
        else if (PosId == PointPos::mid)
            return aoh->getCenter();
    } else if (geo->getTypeId() == Part::GeomArcOfParabola::getClassTypeId()) {
        const Part::GeomArcOfParabola *aop = static_cast<const Part::GeomArcOfParabola*>(geo);
        if (PosId == PointPos::start)
            return aop->getStartPoint();
        else if (PosId == PointPos::end)
            return aop->getEndPoint();
        else if (PosId == PointPos::mid)
            return aop->getCenter();
    } else if (geo->getTypeId() == Part::GeomBSplineCurve::getClassTypeId()) {
        const Part::GeomBSplineCurve *bsp = static_cast<const Part::GeomBSplineCurve*>(geo);
        if (PosId == PointPos::start)
            return bsp->getStartPoint();
        else if (PosId == PointPos::end)
            return bsp->getEndPoint();
    }

    return Base::Vector3d();
}

int SketchObject::getAxisCount() const
{
    const std::vector< Part::Geometry * > &vals = getInternalGeometry();

    int count=0;
    for (std::vector<Part::Geometry *>::const_iterator geo=vals.begin();
        geo != vals.end(); geo++)
        if ((*geo) && GeometryFacade::getConstruction(*geo) &&
            (*geo)->getTypeId() == Part::GeomLineSegment::getClassTypeId())
            count++;

    return count;
}

Base::Axis SketchObject::getAxis(int axId) const
{
    if (axId == H_Axis || axId == V_Axis || axId == N_Axis)
        return Part::Part2DObject::getAxis(axId);

    const std::vector< Part::Geometry * > &vals = getInternalGeometry();
    int count=0;
    for (std::vector<Part::Geometry *>::const_iterator geo=vals.begin();
        geo != vals.end(); geo++)
        if ((*geo) && GeometryFacade::getConstruction(*geo) &&
            (*geo)->getTypeId() == Part::GeomLineSegment::getClassTypeId()) {
            if (count == axId) {
                Part::GeomLineSegment *lineSeg = static_cast<Part::GeomLineSegment*>(*geo);
                Base::Vector3d start = lineSeg->getStartPoint();
                Base::Vector3d end = lineSeg->getEndPoint();
                return Base::Axis(start, end-start);
            }
            count++;
        }

    return Base::Axis();
}

void SketchObject::acceptGeometry()
{
    Constraints.acceptGeometry(getCompleteGeometry());
    rebuildVertexIndex();
}

bool SketchObject::isSupportedGeometry(const Part::Geometry *geo) const
{
    if (geo->getTypeId() == Part::GeomPoint::getClassTypeId() ||
        geo->getTypeId() == Part::GeomCircle::getClassTypeId() ||
        geo->getTypeId() == Part::GeomEllipse::getClassTypeId() ||
        geo->getTypeId() == Part::GeomArcOfCircle::getClassTypeId() ||
        geo->getTypeId() == Part::GeomArcOfEllipse::getClassTypeId() ||
        geo->getTypeId() == Part::GeomArcOfHyperbola::getClassTypeId() ||
        geo->getTypeId() == Part::GeomArcOfParabola::getClassTypeId() ||
        geo->getTypeId() == Part::GeomBSplineCurve::getClassTypeId() ||
        geo->getTypeId() == Part::GeomLineSegment::getClassTypeId()) {
        return true;
    }
    if (geo->getTypeId() == Part::GeomTrimmedCurve::getClassTypeId()) {
        Handle(Geom_TrimmedCurve) trim = Handle(Geom_TrimmedCurve)::DownCast(geo->handle());
        Handle(Geom_Circle) circle = Handle(Geom_Circle)::DownCast(trim->BasisCurve());
        Handle(Geom_Ellipse) ellipse = Handle(Geom_Ellipse)::DownCast(trim->BasisCurve());
        if (!circle.IsNull() || !ellipse.IsNull()) {
            return true;
        }
    }
    return false;
}

std::vector<Part::Geometry *> SketchObject::supportedGeometry(const std::vector<Part::Geometry *> &geoList) const
{
    std::vector<Part::Geometry *> supportedGeoList;
    supportedGeoList.reserve(geoList.size());
    // read-in geometry that the sketcher cannot handle
    for (std::vector<Part::Geometry*>::const_iterator it = geoList.begin(); it != geoList.end(); ++it) {
        if (isSupportedGeometry(*it)) {
            supportedGeoList.push_back(*it);
        }
    }

    return supportedGeoList;
}

int SketchObject::addGeometry(const std::vector<Part::Geometry *> &geoList, bool construction/*=false*/)
{
    Base::StateLocker lock(managedoperation, true); // no need to check input data validity as this is an sketchobject managed operation.

    const std::vector< Part::Geometry * > &vals = getInternalGeometry();

    std::vector< Part::Geometry * > newVals(vals);
    newVals.reserve(newVals.size() + geoList.size());
    for( auto & v : geoList) {
        Part::Geometry* copy = v->copy();

        if( copy->getTypeId() == Part::GeomPoint::getClassTypeId()) {
            // creation mode for points is always construction not to
            // break legacy code
            GeometryFacade::setConstruction(copy, true);
        }
        else if(construction) {
            GeometryFacade::setConstruction(copy, construction);
        }

        newVals.push_back(copy);
    }

    // On setting geometry the onChanged method will call acceptGeometry(), thereby updating constraint geometry indices and rebuilding the vertex index
    Geometry.setValues(std::move(newVals));

    return Geometry.getSize()-1;
}

int SketchObject::addGeometry(const Part::Geometry *geo, bool construction/*=false*/)
{
    // this copy has a new random tag (see copy() vs clone())
    auto geoNew = std::unique_ptr<Part::Geometry>(geo->copy());

    return addGeometry(std::move(geoNew),construction);
}

int SketchObject::addGeometry(std::unique_ptr<Part::Geometry> newgeo, bool construction/*=false*/)
{
    Base::StateLocker lock(managedoperation, true); // no need to check input data validity as this is an sketchobject managed operation.

    const std::vector< Part::Geometry * > &vals = getInternalGeometry();

    std::vector< Part::Geometry * > newVals(vals);

    auto *geoNew = newgeo.release();

    if( geoNew->getTypeId() == Part::GeomPoint::getClassTypeId()) {
        // creation mode for points is always construction not to
        // break legacy code
        GeometryFacade::setConstruction(geoNew, true);
    }
    else if(construction) {
        GeometryFacade::setConstruction(geoNew, construction);
    }

    newVals.push_back(geoNew);

    // On setting geometry the onChanged method will call acceptGeometry(), thereby updating constraint geometry indices and rebuilding the vertex index
    Geometry.setValues(std::move(newVals));

    return Geometry.getSize()-1;
}

int SketchObject::delGeometry(int GeoId, bool deleteinternalgeo)
{
    Base::StateLocker lock(managedoperation, true); // no need to check input data validity as this is an sketchobject managed operation.

    const std::vector< Part::Geometry * > &vals = getInternalGeometry();
    if (GeoId < 0 || GeoId >= int(vals.size()))
        return -1;

    if (deleteinternalgeo) {
        const Part::Geometry *geo = getGeometry(GeoId);
        // Only for supported types
        if ((geo->getTypeId() == Part::GeomEllipse::getClassTypeId() ||
             geo->getTypeId() == Part::GeomArcOfEllipse::getClassTypeId() ||
             geo->getTypeId() == Part::GeomArcOfHyperbola::getClassTypeId() ||
             geo->getTypeId() == Part::GeomArcOfParabola::getClassTypeId() ||
             geo->getTypeId() == Part::GeomBSplineCurve::getClassTypeId())) {

            this->deleteUnusedInternalGeometry(GeoId, true);

            return 0;
        }
    }

    std::vector< Part::Geometry * > newVals(vals);
    newVals.erase(newVals.begin()+GeoId);

    // Find coincident points to replace the points of the deleted geometry
    std::vector<int> GeoIdList;
    std::vector<PointPos> PosIdList;
    for (PointPos PosId = PointPos::start; PosId != PointPos::mid; ) {
        getDirectlyCoincidentPoints(GeoId, PosId, GeoIdList, PosIdList);
        if (GeoIdList.size() > 1) {
            delConstraintOnPoint(GeoId, PosId, true /* only coincidence */);
            transferConstraints(GeoIdList[0], PosIdList[0], GeoIdList[1], PosIdList[1]);
        }
        PosId = (PosId == PointPos::start) ? PointPos::end : PointPos::mid; // loop through [start, end, mid]
    }

    const std::vector< Constraint * > &constraints = this->Constraints.getValues();
    std::vector< Constraint * > newConstraints;
    newConstraints.reserve(constraints.size());
    for (auto cstr : constraints) {
        if (cstr->First == GeoId || cstr->Second == GeoId || cstr->Third == GeoId)
            continue;
        if (cstr->First > GeoId || cstr->Second > GeoId || cstr->Third > GeoId) {
            cstr = cstr->clone();
            if (cstr->First > GeoId)
                cstr->First -= 1;
            if (cstr->Second > GeoId)
                cstr->Second -= 1;
            if (cstr->Third > GeoId)
                cstr->Third -= 1;
        }
        newConstraints.push_back(cstr);
    }

    // Block acceptGeometry in OnChanged to avoid unnecessary checks and updates
    {
        Base::StateLocker lock(internaltransaction, true);
        this->Geometry.setValues(std::move(newVals));
        this->Constraints.setValues(std::move(newConstraints));
    }

    // Update geometry indices and rebuild vertexindex now via onChanged, so that ViewProvider::UpdateData is triggered.
    Geometry.touch();

    if(noRecomputes) // if we do not have a recompute, the sketch must be solved to update the DoF of the solver
        solve();

    return 0;
}


int SketchObject::delGeometries(const std::vector<int>& GeoIds)
{
    std::vector<int> sGeoIds(GeoIds);

    // if a GeoId has internal geometry, it must delete internal geometries too
    for(auto c : Constraints.getValues())  {
        if( c->Type == InternalAlignment ) {
            auto pos = std::find(sGeoIds.begin(), sGeoIds.end(), c->Second);

            if(pos != sGeoIds.end()) {
                sGeoIds.push_back(c->First);
            }
        }
    }

    std::sort(sGeoIds.begin(), sGeoIds.end());
    // eliminate duplicates
    auto newend = std::unique(sGeoIds.begin(), sGeoIds.end());
    sGeoIds.resize(std::distance(sGeoIds.begin(), newend));

    return delGeometriesExclusiveList(sGeoIds);
}

int SketchObject::delGeometriesExclusiveList(const std::vector<int>& GeoIds)
{
    std::vector<int> sGeoIds(GeoIds);

    std::sort(sGeoIds.begin(), sGeoIds.end());
    if (sGeoIds.empty())
        return 0;

    Base::StateLocker lock(managedoperation, true); // no need to check input data validity as this is an sketchobject managed operation.

    const std::vector< Part::Geometry * > &vals = getInternalGeometry();
    if (sGeoIds.front() < 0 || sGeoIds.back() >= int(vals.size()))
        return -1;


    std::vector< Part::Geometry * > newVals(vals);
    for (auto it = sGeoIds.rbegin(); it != sGeoIds.rend(); ++it) {
        int GeoId = *it;
        newVals.erase(newVals.begin() + GeoId);

        // Find coincident points to replace the points of the deleted geometry
        std::vector<int> GeoIdList;
        std::vector<PointPos> PosIdList;
        for (PointPos PosId = PointPos::start; PosId != PointPos::mid; ) {
            getDirectlyCoincidentPoints(GeoId, PosId, GeoIdList, PosIdList);
            if (GeoIdList.size() > 1) {
                delConstraintOnPoint(GeoId, PosId, true /* only coincidence */);
                transferConstraints(GeoIdList[0], PosIdList[0], GeoIdList[1], PosIdList[1]);
            }
            PosId = (PosId == PointPos::start) ? PointPos::end : PointPos::mid; // loop through [start, end, mid]
        }
    }

    // Copy the original constraints
    std::vector< Constraint* > constraints;
    for (const auto ptr : this->Constraints.getValues())
        constraints.push_back(ptr->clone());
    std::vector< Constraint* > filteredConstraints(0);
    for (auto itGeo = sGeoIds.rbegin(); itGeo != sGeoIds.rend(); ++itGeo) {
        int GeoId = *itGeo;
        for (std::vector<Constraint*>::const_iterator it = constraints.begin();
             it != constraints.end(); ++it) {

            Constraint* copiedConstr(*it);
            if ((*it)->First != GeoId && (*it)->Second != GeoId && (*it)->Third != GeoId) {
                if (copiedConstr->First > GeoId)
                    copiedConstr->First -= 1;
                if (copiedConstr->Second > GeoId)
                    copiedConstr->Second -= 1;
                if (copiedConstr->Third > GeoId)
                    copiedConstr->Third -= 1;
                filteredConstraints.push_back(copiedConstr);
            }
            else {
                delete copiedConstr;
            }
        }

        constraints = filteredConstraints;
        filteredConstraints.clear();
    }

    // Block acceptGeometry in OnChanged to avoid unnecessary checks and updates
    {
        Base::StateLocker lock(internaltransaction, true);
        this->Geometry.setValues(newVals);
        this->Constraints.setValues(std::move(constraints));
    }
    // Update geometry indices and rebuild vertexindex now via onChanged, so that ViewProvider::UpdateData is triggered.
    Geometry.touch();

    if (noRecomputes) // if we do not have a recompute, the sketch must be solved to update the DoF of the solver
        solve();

    return 0;
}

int SketchObject::deleteAllGeometry()
{
    Base::StateLocker lock(managedoperation, true); // no need to check input data validity as this is an sketchobject managed operation.

    std::vector< Part::Geometry * > newVals(0);
    std::vector< Constraint * > newConstraints(0);

    // Avoid unnecessary updates and checks as this is a transaction
    {
        Base::StateLocker lock(internaltransaction, true);
        this->Geometry.setValues(newVals);
        this->Constraints.setValues(newConstraints);
    }
    // Update geometry indices and rebuild vertexindex now via onChanged, so that ViewProvider::UpdateData is triggered.
    Geometry.touch();

    if(noRecomputes) // if we do not have a recompute, the sketch must be solved to update the DoF of the solver
        solve();

    return 0;
}

int SketchObject::deleteAllConstraints()
{
    Base::StateLocker lock(managedoperation, true); // no need to check input data validity as this is an sketchobject managed operation.

    std::vector< Constraint * > newConstraints(0);

    this->Constraints.setValues(newConstraints);

    if(noRecomputes) // if we do not have a recompute, the sketch must be solved to update the DoF of the solver
        solve();

    return 0;
}

int SketchObject::toggleConstruction(int GeoId)
{
    Base::StateLocker lock(managedoperation, true); // no need to check input data validity as this is an sketchobject managed operation.

    const std::vector< Part::Geometry * > &vals = getInternalGeometry();
    if (GeoId < 0 || GeoId >= int(vals.size()))
        return -1;

    if(getGeometryFacade(GeoId)->isInternalAligned())
        return -1;

    // While it may seem that there is not a need to trigger an update at this time, because the solver has its own copy of the geometry,
    // and updateColors of the viewprovider may be triggered by the clearselection of the UI command, this won't update the elements widget,
    // in the accumulative of actions it is judged that it is worth to trigger an update here.

    std::unique_ptr<Part::Geometry> geo(vals[GeoId]->clone());
    auto gft = GeometryFacade::getFacade(geo.get());
    gft->setConstruction(!gft->getConstruction());
    this->Geometry.set1Value(GeoId, std::move(geo));

    solverNeedsUpdate=true;
    return 0;
}

int SketchObject::setConstruction(int GeoId, bool on)
{
    Base::StateLocker lock(managedoperation, true); // no need to check input data validity as this is an sketchobject managed operation.

    const std::vector< Part::Geometry * > &vals = getInternalGeometry();
    if (GeoId < 0 || GeoId >= int(vals.size()))
        return -1;

    if(getGeometryFacade(GeoId)->isInternalAligned())
        return -1;

    // While it may seem that there is not a need to trigger an update at this time, because the solver has its own copy of the geometry,
    // and updateColors of the viewprovider may be triggered by the clearselection of the UI command, this won't update the elements widget,
    // in the accumulative of actions it is judged that it is worth to trigger an update here.

    std::unique_ptr<Part::Geometry> geo(vals[GeoId]->clone());
    GeometryFacade::setConstruction(geo.get(), on);
    this->Geometry.set1Value(GeoId, std::move(geo));

    solverNeedsUpdate=true;
    return 0;
}

void SketchObject::addGeometryState(const Constraint* cstr) const
{
    const std::vector< Part::Geometry * > &vals = getInternalGeometry();

    Sketcher::InternalType::InternalType constraintInternalAlignment = InternalType::None;
    bool constraintBlockedState = false;

    if (getInternalTypeState(cstr, constraintInternalAlignment)) {
        auto gf = GeometryFacade::getFacade(vals[cstr->First]);
        gf->setInternalType(constraintInternalAlignment);
    }
    else if (getBlockedState(cstr, constraintBlockedState)) {
        auto gf = GeometryFacade::getFacade(vals[cstr->First]);
        gf->setBlocked(constraintBlockedState);
    }
}

void SketchObject::removeGeometryState(const Constraint* cstr) const
{
    const std::vector< Part::Geometry * > &vals = getInternalGeometry();

    // Assign correct Internal Geometry Type (see SketchGeometryExtension)
    if(cstr->Type == InternalAlignment) {
        auto gf = GeometryFacade::getFacade(vals[cstr->First]);
        gf->setInternalType(InternalType::None);
    }

    // Assign Blocked geometry mode (see SketchGeometryExtension)
    if(cstr->Type == Block){
        auto gf = GeometryFacade::getFacade(vals[cstr->First]);
        gf->setBlocked(false);
    }
}

//ConstraintList is used only to make copies.
int SketchObject::addConstraints(const std::vector<Constraint *> &ConstraintList)
{
    Base::StateLocker lock(managedoperation, true); // no need to check input data validity as this is an sketchobject managed operation.

    const std::vector< Constraint * > &vals = this->Constraints.getValues();

    std::vector< Constraint * > newVals(vals);
    newVals.insert(newVals.end(), ConstraintList.begin(), ConstraintList.end());
    for(std::size_t i = newVals.size()-ConstraintList.size(); i<newVals.size(); i++){
        Constraint *cnew = newVals[i]->clone();
        newVals[i] = cnew;

        if( cnew->Type == Tangent || cnew->Type == Perpendicular ){
            AutoLockTangencyAndPerpty(cnew);
        }

        addGeometryState(cnew);
    }

    this->Constraints.setValues(std::move(newVals));

    return this->Constraints.getSize()-1;
}

int SketchObject::addCopyOfConstraints(const SketchObject &orig)
{
    Base::StateLocker lock(managedoperation, true); // no need to check input data validity as this is an sketchobject managed operation.

    const std::vector< Constraint * > &vals = this->Constraints.getValues();

    const std::vector< Constraint * > &origvals = orig.Constraints.getValues();

    std::vector< Constraint * > newVals(vals);

    newVals.reserve(vals.size()+origvals.size());

    for( auto & v : origvals )
        newVals.push_back(v->copy());

    this->Constraints.setValues(std::move(newVals));

    auto & uvals = this->Constraints.getValues();

    std::size_t uvalssize = uvals.size();

    for(std::size_t i = uvalssize, j = 0; i<uvals.size(); i++,j++){
        if ( uvals[i]->isDriving && uvals[i]->isDimensional()) {

            App::ObjectIdentifier spath = orig.Constraints.createPath(j);

            App::PropertyExpressionEngine::ExpressionInfo expr_info = orig.getExpression(spath);

            if (expr_info.expression) { // if there is an expression on the source dimensional
                App::ObjectIdentifier dpath = this->Constraints.createPath(i);
                setExpression(dpath, std::shared_ptr<App::Expression>(expr_info.expression->copy()));
            }
        }
    }

    return this->Constraints.getSize()-1;
}

int SketchObject::addConstraint(const Constraint *constraint)
{
    auto constraint_ptr = std::unique_ptr<Constraint>(constraint->clone());

    return addConstraint(std::move(constraint_ptr));
}

int SketchObject::addConstraint(std::unique_ptr<Constraint> constraint)
{
    Base::StateLocker lock(managedoperation, true); // no need to check input data validity as this is an sketchobject managed operation.

    const std::vector< Constraint * > &vals = this->Constraints.getValues();

    std::vector< Constraint * > newVals(vals);

    Constraint *constNew = constraint.release();

    if (constNew->Type == Tangent || constNew->Type == Perpendicular)
        AutoLockTangencyAndPerpty(constNew);

    addGeometryState(constNew);

    newVals.push_back(constNew); // add new constraint at the back

    this->Constraints.setValues(std::move(newVals));

    return this->Constraints.getSize()-1;
}

int SketchObject::delConstraint(int ConstrId)
{
    Base::StateLocker lock(managedoperation, true); // no need to check input data validity as this is an sketchobject managed operation.

    const std::vector< Constraint * > &vals = this->Constraints.getValues();
    if (ConstrId < 0 || ConstrId >= int(vals.size()))
        return -1;

    std::vector< Constraint * > newVals(vals);
    auto ctriter = newVals.begin()+ConstrId;
    removeGeometryState(*ctriter);
    newVals.erase(ctriter);
    this->Constraints.setValues(std::move(newVals));

    if(noRecomputes) // if we do not have a recompute, the sketch must be solved to update the DoF of the solver
        solve();

    return 0;
}

int SketchObject::delConstraints(std::vector<int> ConstrIds, bool updategeometry)
{
    Base::StateLocker lock(managedoperation, true); // no need to check input data validity as this is an sketchobject managed operation.
    if (ConstrIds.empty())
        return 0;

    const std::vector< Constraint * > &vals = this->Constraints.getValues();

    std::vector< Constraint * > newVals(vals);

    std::sort(ConstrIds.begin(),ConstrIds.end());

    if (ConstrIds.front() < 0 || ConstrIds.back() >= int(vals.size()))
        return -1;

    for(auto rit = ConstrIds.rbegin(); rit!=ConstrIds.rend(); rit++) {
        auto ctriter = newVals.begin()+*rit;
        removeGeometryState(*ctriter);
        newVals.erase(ctriter);
    }

    this->Constraints.setValues(std::move(newVals));

    if(noRecomputes) // if we do not have a recompute, the sketch must be solved to update the DoF of the solver
        solve(updategeometry);

    return 0;
}

int SketchObject::delConstraintOnPoint(int VertexId, bool onlyCoincident)
{
    int GeoId;
    PointPos PosId;
    if (VertexId == GeoEnum::RtPnt) { // RootPoint
        GeoId = Sketcher::GeoEnum::RtPnt;
        PosId = PointPos::start;
    } else
        getGeoVertexIndex(VertexId, GeoId, PosId);

    return delConstraintOnPoint(GeoId, PosId, onlyCoincident);
}

int SketchObject::delConstraintOnPoint(int GeoId, PointPos PosId, bool onlyCoincident)
{
    Base::StateLocker lock(managedoperation, true); // no need to check input data validity as this is an sketchobject managed operation.

    const std::vector<Constraint *> &vals = this->Constraints.getValues();

    // check if constraints can be redirected to some other point
    int replaceGeoId=GeoEnum::GeoUndef;
    PointPos replacePosId=Sketcher::PointPos::none;
    if (!onlyCoincident) {
        for (std::vector<Constraint *>::const_iterator it = vals.begin(); it != vals.end(); ++it) {
            if ((*it)->Type == Sketcher::Coincident) {
                if ((*it)->First == GeoId && (*it)->FirstPos == PosId) {
                    replaceGeoId = (*it)->Second;
                    replacePosId = (*it)->SecondPos;
                    break;
                }
                else if ((*it)->Second == GeoId && (*it)->SecondPos == PosId) {
                    replaceGeoId = (*it)->First;
                    replacePosId = (*it)->FirstPos;
                    break;
                }
            }
        }
    }

    // remove or redirect any constraints associated with the given point
    std::vector<Constraint *> newVals(0);
    for (std::vector<Constraint *>::const_iterator it = vals.begin(); it != vals.end(); ++it) {
        if ((*it)->Type == Sketcher::Coincident) {
            if ((*it)->First == GeoId && (*it)->FirstPos == PosId) {
                if (replaceGeoId != GeoEnum::GeoUndef &&
                    (replaceGeoId != (*it)->Second || replacePosId != (*it)->SecondPos)) { // redirect this constraint
                    (*it)->First = replaceGeoId;
                    (*it)->FirstPos = replacePosId;
                }
                else
                    continue; // skip this constraint
            }
            else if ((*it)->Second == GeoId && (*it)->SecondPos == PosId) {
                if (replaceGeoId != GeoEnum::GeoUndef &&
                    (replaceGeoId != (*it)->First || replacePosId != (*it)->FirstPos)) { // redirect this constraint
                    (*it)->Second = replaceGeoId;
                    (*it)->SecondPos = replacePosId;
                }
                else
                    continue; // skip this constraint
            }
        }
        else if (!onlyCoincident) {
            if ((*it)->Type == Sketcher::Distance ||
                (*it)->Type == Sketcher::DistanceX || (*it)->Type == Sketcher::DistanceY) {
                if ((*it)->First == GeoId && (*it)->FirstPos == PointPos::none &&
                    (PosId == PointPos::start || PosId == PointPos::end)) {
                    // remove the constraint even if it is not directly associated
                    // with the given point
                    continue; // skip this constraint
                }
                else if ((*it)->First == GeoId && (*it)->FirstPos == PosId) {
                    if (replaceGeoId != GeoEnum::GeoUndef) { // redirect this constraint
                        (*it)->First = replaceGeoId;
                        (*it)->FirstPos = replacePosId;
                    }
                    else
                        continue; // skip this constraint
                }
                else if ((*it)->Second == GeoId && (*it)->SecondPos == PosId) {
                    if (replaceGeoId != GeoEnum::GeoUndef) { // redirect this constraint
                        (*it)->Second = replaceGeoId;
                        (*it)->SecondPos = replacePosId;
                    }
                    else
                        continue; // skip this constraint
                }
            }
            else if ((*it)->Type == Sketcher::PointOnObject) {
                if ((*it)->First == GeoId && (*it)->FirstPos == PosId) {
                    if (replaceGeoId != GeoEnum::GeoUndef) { // redirect this constraint
                        (*it)->First = replaceGeoId;
                        (*it)->FirstPos = replacePosId;
                    }
                    else
                        continue; // skip this constraint
                }
            }
            else if ((*it)->Type == Sketcher::Tangent || (*it)->Type == Sketcher::Perpendicular) {
                if (((*it)->First == GeoId && (*it)->FirstPos == PosId) ||
                    ((*it)->Second == GeoId && (*it)->SecondPos == PosId)) {
                    // we could keep the tangency constraint by converting it
                    // to a simple one but it is not really worth
                    continue; // skip this constraint
                }
            }
            else if ((*it)->Type == Sketcher::Symmetric) {
                if (((*it)->First == GeoId && (*it)->FirstPos == PosId) ||
                    ((*it)->Second == GeoId && (*it)->SecondPos == PosId)) {
                    continue; // skip this constraint
                }
            }
            else if ((*it)->Type == Sketcher::Vertical || (*it)->Type == Sketcher::Horizontal) {
                if (((*it)->First == GeoId && (*it)->FirstPos == PosId) ||
                    ((*it)->Second == GeoId && (*it)->SecondPos == PosId)) {
                    continue; // skip this constraint
                }
            }
        }
        newVals.push_back(*it);
    }
    if (newVals.size() < vals.size()) {
        this->Constraints.setValues(std::move(newVals));

        return 0;
    }

    return -1; // no such constraint
}

void SketchObject::transferFilletConstraints(int geoId1, PointPos posId1, int geoId2, PointPos posId2) {
    // If the lines don't intersect, there's no original corner to work with so
    // don't try to transfer the constraints. But we should delete line length and equal
    // constraints and constraints on the affected endpoints because they're about
    // to move unpredictably.
    if (!arePointsCoincident(geoId1, posId1, geoId2, posId2)) {
        // Delete constraints on the endpoints
        delConstraintOnPoint(geoId1, posId1, false);
        delConstraintOnPoint(geoId2, posId2, false);

        // Delete line length and equal constraints
        const std::vector<Constraint *> &constraints = this->Constraints.getValues();
        std::vector<int> deleteme;
        for (int i=0; i < int(constraints.size()); i++) {
            const Constraint *c = constraints[i];
            if (c->Type == Sketcher::Distance || c->Type == Sketcher::Equal) {
                bool line1 = c->First == geoId1 && c->FirstPos == PointPos::none;
                bool line2 = c->First == geoId2 && c->FirstPos == PointPos::none;
                if (line1 || line2) {
                  deleteme.push_back(i);
                }
            }
        }
        delConstraints(deleteme, false);
        return;
    }

    // If the lines aren't straight, don't try to transfer the constraints.
    // TODO: Add support for curved lines.
    const Part::Geometry *geo1 = getGeometry(geoId1);
    const Part::Geometry *geo2 = getGeometry(geoId2);
    if (geo1->getTypeId() != Part::GeomLineSegment::getClassTypeId() ||
        geo2->getTypeId() != Part::GeomLineSegment::getClassTypeId() ) {
        delConstraintOnPoint(geoId1, posId1, false);
        delConstraintOnPoint(geoId2, posId2, false);
        return;
    }

    // Add a vertex to preserve the original intersection of the filleted lines
    Part::GeomPoint *originalCorner = new Part::GeomPoint(getPoint(geoId1, posId1));
    int originalCornerId = addGeometry(originalCorner);
    delete originalCorner;

    // Constrain the vertex to the two lines
    Sketcher::Constraint *cornerToLine1 = new Sketcher::Constraint();
    cornerToLine1->Type = Sketcher::PointOnObject;
    cornerToLine1->First = originalCornerId;
    cornerToLine1->FirstPos = PointPos::start;
    cornerToLine1->Second = geoId1;
    cornerToLine1->SecondPos = PointPos::none;
    addConstraint(cornerToLine1);
    delete cornerToLine1;
    Sketcher::Constraint *cornerToLine2 = new Sketcher::Constraint();
    cornerToLine2->Type = Sketcher::PointOnObject;
    cornerToLine2->First = originalCornerId;
    cornerToLine2->FirstPos = PointPos::start;
    cornerToLine2->Second = geoId2;
    cornerToLine2->SecondPos = PointPos::none;
    addConstraint(cornerToLine2);
    delete cornerToLine2;

    Base::StateLocker lock(managedoperation, true);

    // Loop through all the constraints and try to do reasonable things with the affected ones
    std::vector<Constraint *> newConstraints;
    for (auto c : this->Constraints.getValues()) {
        // Keep track of whether the affected lines and endpoints appear in this constraint
        bool point1First = c->First == geoId1 && c->FirstPos == posId1;
        bool point2First = c->First == geoId2 && c->FirstPos == posId2;
        bool point1Second = c->Second == geoId1 && c->SecondPos == posId1;
        bool point2Second = c->Second == geoId2 && c->SecondPos == posId2;
        bool point1Third = c->Third == geoId1 && c->ThirdPos == posId1;
        bool point2Third = c->Third == geoId2 && c->ThirdPos == posId2;
        bool line1First = c->First == geoId1 && c->FirstPos == PointPos::none;
        bool line2First = c->First == geoId2 && c->FirstPos == PointPos::none;
        bool line1Second = c->Second == geoId1 && c->SecondPos == PointPos::none;
        bool line2Second = c->Second == geoId2 && c->SecondPos == PointPos::none;

        if (c->Type == Sketcher::Coincident) {
            if ((point1First && point2Second) || (point2First && point1Second)) {
                // This is the constraint holding the two edges together that are about to be filleted.  This constraint
                // goes away because the edges will touch the fillet instead.
                continue;
            }
            if (point1First || point2First) {
                // Move the coincident constraint to the new corner point
                c->First = originalCornerId;
                c->FirstPos = PointPos::start;
            }
            if (point1Second || point2Second) {
                // Move the coincident constraint to the new corner point
                c->Second = originalCornerId;
                c->SecondPos = PointPos::start;
            }
        } else if (c->Type == Sketcher::Horizontal || c->Type == Sketcher::Vertical) {
            // Point-to-point horizontal or vertical constraint, move to new corner point
            if (point1First || point2First) {
                c->First = originalCornerId;
                c->FirstPos = PointPos::start;
            }
            if (point1Second || point2Second) {
                c->Second = originalCornerId;
                c->SecondPos = PointPos::start;
            }
        } else if (c->Type == Sketcher::Distance || c->Type == Sketcher::DistanceX || c->Type == Sketcher::DistanceY) {
            // Point-to-point distance constraint.  Move it to the new corner point
            if (point1First || point2First) {
                c->First = originalCornerId;
                c->FirstPos = PointPos::start;
            }
            if (point1Second || point2Second) {
                c->Second = originalCornerId;
                c->SecondPos = PointPos::start;
            }

            // Distance constraint on the line itself. Change it to point-point between the far end of the line
            // and the new corner
            if (line1First) {
                c->FirstPos = (posId1 == PointPos::start) ? PointPos::end : PointPos::start;
                c->Second = originalCornerId;
                c->SecondPos = PointPos::start;
            }
            if (line2First) {
                c->FirstPos = (posId2 == PointPos::start) ? PointPos::end : PointPos::start;
                c->Second = originalCornerId;
                c->SecondPos = PointPos::start;
            }
        } else if (c->Type == Sketcher::PointOnObject) {
            // The corner to be filleted was touching some other object.
            if (point1First || point2First) {
                c->First = originalCornerId;
                c->FirstPos = PointPos::start;
            }
        } else if (c->Type == Sketcher::Equal) {
            // Equal length constraints are dicey because the lines are getting shorter.  Safer to
            // delete them and let the user notice the underconstraint.
            if (line1First || line2First || line1Second || line2Second) {
                continue;
            }
        } else if (c->Type == Sketcher::Symmetric) {
            // Symmetries should probably be preserved relative to the original corner
            if (point1First || point2First) {
                c->First = originalCornerId;
                c->FirstPos = PointPos::start;
            } else if (point1Second || point2Second) {
                c->Second = originalCornerId;
                c->SecondPos = PointPos::start;
            } else if (point1Third || point2Third) {
                c->Third = originalCornerId;
                c->ThirdPos = PointPos::start;
            }
        } else if (c->Type == Sketcher::SnellsLaw) {
          // Can't imagine any cases where you'd fillet a vertex going through a lens, so let's
          // delete to be safe.
          continue;
        } else if (point1First || point2First || point1Second || point2Second || point1Third || point2Third) {
          // Delete any other point-based constraints on the relevant points
          continue;
        }

        // Default: keep all other constraints
        newConstraints.push_back(c->clone());
    }
    this->Constraints.setValues(std::move(newConstraints));
}

int SketchObject::transferConstraints(int fromGeoId, PointPos fromPosId, int toGeoId, PointPos toPosId, bool doNotTransformTangencies)
{
    Base::StateLocker lock(managedoperation, true); // no need to check input data validity as this is an sketchobject managed operation.

    const std::vector<Constraint *> &vals = this->Constraints.getValues();
    std::vector<Constraint *> newVals(vals);
    bool changed = false;
    for (int i=0; i < int(newVals.size()); i++) {
        if (vals[i]->First == fromGeoId && vals[i]->FirstPos == fromPosId &&
            !(vals[i]->Second == toGeoId && vals[i]->SecondPos == toPosId) &&
            !(toGeoId < 0 && vals[i]->Second <0) ) {

            std::unique_ptr<Constraint> constNew(newVals[i]->clone());
            constNew->First = toGeoId;
            constNew->FirstPos = toPosId;

            // If not explicitly confirmed, nothing guarantees that a tangent can be freely transferred to another coincident
            // point, as the transfer destination edge most likely won't be intended to be tangent. However, if it is
            // an end to end point tangency, the user expects it to be substituted by a coincidence constraint.
            if (vals[i]->Type == Sketcher::Tangent || vals[i]->Type == Sketcher::Perpendicular) {
                if (!doNotTransformTangencies) {
                    constNew->Type = Sketcher::Coincident;
                }
            }
            // With respect to angle constraints, if it is a DeepSOIC style angle constraint (segment+segment+point),
            // then no problem arises as the segments are PosId=none. In this case there is no call to this function.
            //
            // However, other angle constraints are problematic because they are created on segments, but internally
            // operate on vertices, PosId=start
            // Such constraint may not be successfully transferred on deletion of the segments.
            else if(vals[i]->Type == Sketcher::Angle) {
                continue;
            }

            Constraint* constPtr = constNew.release();
            newVals[i] = constPtr;
            changed = true;
        }
        else if (vals[i]->Second == fromGeoId && vals[i]->SecondPos == fromPosId &&
                 !(vals[i]->First == toGeoId && vals[i]->FirstPos == toPosId) &&
                 !(toGeoId < 0 && vals[i]->First< 0)) {

            std::unique_ptr<Constraint> constNew(newVals[i]->clone());
            constNew->Second = toGeoId;
            constNew->SecondPos = toPosId;
            // If not explicitly confirmed, nothing guarantees that a tangent can be freely transferred to another coincident
            // point, as the transfer destination edge most likely won't be intended to be tangent. However, if it is
            // an end to end point tangency, the user expects it to be substituted by a coincidence constraint.
            if (vals[i]->Type == Sketcher::Tangent || vals[i]->Type == Sketcher::Perpendicular) {
                if (!doNotTransformTangencies) {
                    constNew->Type = Sketcher::Coincident;
                }
            }
            else if(vals[i]->Type == Sketcher::Angle) {
                continue;
            }

            Constraint* constPtr = constNew.release();
            newVals[i] = constPtr;
            changed = true;
        }
    }

    // assign the new values only if something has changed
    if (changed) {
        this->Constraints.setValues(std::move(newVals));
    }
    return 0;
}

int SketchObject::fillet(int GeoId, PointPos PosId, double radius, bool trim, bool createCorner)
{
    if (GeoId < 0 || GeoId > getHighestCurveIndex())
        return -1;

    // Find the other geometry Id associated with the coincident point
    std::vector<int> GeoIdList;
    std::vector<PointPos> PosIdList;
    getDirectlyCoincidentPoints(GeoId, PosId, GeoIdList, PosIdList);

    // only coincident points between two (non-external) edges can be filleted
    if (GeoIdList.size() == 2 && GeoIdList[0] >= 0 && GeoIdList[1] >= 0) {
        const Part::Geometry *geo1 = getGeometry(GeoIdList[0]);
        const Part::Geometry *geo2 = getGeometry(GeoIdList[1]);
        if (geo1->getTypeId() == Part::GeomLineSegment::getClassTypeId() &&
            geo2->getTypeId() == Part::GeomLineSegment::getClassTypeId() ) {
            const Part::GeomLineSegment *lineSeg1 = static_cast<const Part::GeomLineSegment*>(geo1);
            const Part::GeomLineSegment *lineSeg2 = static_cast<const Part::GeomLineSegment*>(geo2);

            Base::Vector3d midPnt1 = (lineSeg1->getStartPoint() + lineSeg1->getEndPoint()) / 2 ;
            Base::Vector3d midPnt2 = (lineSeg2->getStartPoint() + lineSeg2->getEndPoint()) / 2 ;
            return fillet(GeoIdList[0], GeoIdList[1], midPnt1, midPnt2, radius, trim, createCorner);
        }
    }

    return -1;
}

int SketchObject::fillet(int GeoId1, int GeoId2,
                         const Base::Vector3d& refPnt1, const Base::Vector3d& refPnt2,
                         double radius, bool trim, bool createCorner)
{
    if (GeoId1 < 0 || GeoId1 > getHighestCurveIndex() ||
        GeoId2 < 0 || GeoId2 > getHighestCurveIndex())
        return -1;

    // If either of the two input lines are locked, don't try to trim since it won't work anyway
    const Part::Geometry *geo1 = getGeometry(GeoId1);
    const Part::Geometry *geo2 = getGeometry(GeoId2);
    if (trim && (GeometryFacade::getBlocked(geo1) || GeometryFacade::getBlocked(geo2))) {
        trim = false;
    }

    if (geo1->getTypeId() == Part::GeomLineSegment::getClassTypeId() &&
        geo2->getTypeId() == Part::GeomLineSegment::getClassTypeId() ) {
        const Part::GeomLineSegment *lineSeg1 = static_cast<const Part::GeomLineSegment*>(geo1);
        const Part::GeomLineSegment *lineSeg2 = static_cast<const Part::GeomLineSegment*>(geo2);

        Base::Vector3d filletCenter;
        if (!Part::findFilletCenter(lineSeg1, lineSeg2, radius, refPnt1, refPnt2, filletCenter))
            return -1;
        Base::Vector3d dir1 = lineSeg1->getEndPoint() - lineSeg1->getStartPoint();
        Base::Vector3d dir2 = lineSeg2->getEndPoint() - lineSeg2->getStartPoint();

        // the intersection point will and two distances will be necessary later for trimming the lines
        Base::Vector3d intersection, dist1, dist2;

        // create arc from known parameters and lines
        int filletId;
        std::unique_ptr<Part::GeomArcOfCircle> arc(
            Part::createFilletGeometry(lineSeg1, lineSeg2, filletCenter, radius));
        if (!arc)
            return -1;

        // calculate intersection and distances before we invalidate lineSeg1 and lineSeg2
        if (!find2DLinesIntersection(lineSeg1, lineSeg2, intersection)) {
            return -1;
        }

        dist1.ProjectToLine(arc->getStartPoint(/*emulateCCW=*/true)-intersection, dir1);
        dist2.ProjectToLine(arc->getStartPoint(/*emulateCCW=*/true)-intersection, dir2);
        Part::Geometry *newgeo = arc.get();
        filletId = addGeometry(newgeo);

        if (trim) {
            PointPos PosId1 = (filletCenter-intersection)*dir1 > 0 ? PointPos::start : PointPos::end;
            PointPos PosId2 = (filletCenter-intersection)*dir2 > 0 ? PointPos::start : PointPos::end;

            if (createCorner) {
                transferFilletConstraints(GeoId1, PosId1, GeoId2, PosId2);
            } else {
                delConstraintOnPoint(GeoId1, PosId1, false);
                delConstraintOnPoint(GeoId2, PosId2, false);
            }

            auto tangent1 = std::make_unique<Sketcher::Constraint>();
            auto tangent2 = std::make_unique<Sketcher::Constraint>();

            tangent1->Type = Sketcher::Tangent;
            tangent1->First = GeoId1;
            tangent1->FirstPos = PosId1;
            tangent1->Second = filletId;

            tangent2->Type = Sketcher::Tangent;
            tangent2->First = GeoId2;
            tangent2->FirstPos = PosId2;
            tangent2->Second = filletId;

            if (dist1.Length() < dist2.Length()) {
                tangent1->SecondPos = PointPos::start;
                tangent2->SecondPos = PointPos::end;
                movePoint(GeoId1, PosId1, arc->getStartPoint(/*emulateCCW=*/true),false,true);
                movePoint(GeoId2, PosId2, arc->getEndPoint(/*emulateCCW=*/true),false,true);
            }
            else {
                tangent1->SecondPos = PointPos::end;
                tangent2->SecondPos = PointPos::start;
                movePoint(GeoId1, PosId1, arc->getEndPoint(/*emulateCCW=*/true),false,true);
                movePoint(GeoId2, PosId2, arc->getStartPoint(/*emulateCCW=*/true),false,true);
            }

            addConstraint(std::move(tangent1));
            addConstraint(std::move(tangent2));
        }

        if (noRecomputes) // if we do not have a recompute after the geometry creation, the sketch must be solved to update the DoF of the solver
            solve();

        return 0;
    }
    else if(geo1->isDerivedFrom(Part::GeomBoundedCurve::getClassTypeId())  &&
            geo2->isDerivedFrom(Part::GeomBoundedCurve::getClassTypeId())) {

        auto distancetorefpoints = [](Base::Vector3d ip1, Base::Vector3d ip2, Base::Vector3d ref1, Base::Vector3d ref2) {
                    return (ip1 - ref1).Length() + (ip2 - ref2).Length();
                };

        auto selectintersection = [&distancetorefpoints](std::vector<std::pair<Base::Vector3d, Base::Vector3d>> & points,
                                     std::pair<Base::Vector3d, Base::Vector3d>& interpoints,
                                     const Base::Vector3d& refPnt1, const Base::Vector3d& refPnt2) {

            if (points.empty()) {
                return -1;
            }
            else {
                double dist = distancetorefpoints(points[0].first, points[0].second, refPnt1, refPnt2);
                int i = 0, si = 0;

                for (auto ipoints : points) {
                    double d = distancetorefpoints(ipoints.first, ipoints.second, refPnt1, refPnt2);

                    if (d<dist) {
                        si = i;
                        dist = d;
                    }

                    i++;
                }

                interpoints = points[si];

                return 0;
            }
        };

        // NOTE: While it is not a requirement that the endpoints of the corner to trim are coincident
        //       for GeomTrimmedCurves, it is for GeomBoundedCurves. The reason is that there is no basiscurve
        //       that can be extended to find an intersection.
        //
        //       However, GeomTrimmedCurves sometimes run into problems when trying to calculate the intersection
        //       of basis curves, for example in the case of hyperbola sometimes the cosh goes out of range while
        //       calculating this intersection of basis curves.
        //
        //        Consequently:
        //        i. for GeomBoundedCurves, other than GeomTrimmedCurves, a coincident endpoint is mandatory.
        //        ii. for GeomTrimmedCurves, if there is a coincident endpoint, it is used for the fillet,
        //        iii. for GeomTrimmedCurves, if there is not a coincident endpoint, an intersection of basis curves
        //             is attempted.

        const Part::GeomCurve *curve1 = static_cast<const Part::GeomCurve*>(geo1);
        const Part::GeomCurve *curve2 = static_cast<const Part::GeomCurve*>(geo2);

        double refparam1;
        double refparam2;

        try {
            if(!curve1->closestParameter(refPnt1,refparam1))
                return -1;
        }
        catch (Base::CADKernelError &e) {
            e.ReportException();
            THROWM(Base::CADKernelError, "Unable to determine the parameter of the first selected curve at the reference point.")
        }

        try {
             if(!curve2->closestParameter(refPnt2,refparam2))
                return -1;
        }
        catch (Base::CADKernelError &e) {
            e.ReportException();
            THROWM(Base::CADKernelError, "Unable to determine the parameter of the second selected curve at the reference point.")
        }

#ifdef DEBUG
        Base::Console().Log("\n\nFILLET DEBUG\n\n");
        Base::Console().Log("Ref param: (%f);(%f)",refparam1,refparam2);
#endif

        std::pair<Base::Vector3d, Base::Vector3d> interpoints;
        std::vector<std::pair<Base::Vector3d, Base::Vector3d>> points;


        // look for coincident constraints between curves, take the coincident closest to the refpoints
        Sketcher::PointPos curve1PosId = Sketcher::PointPos::none;
        Sketcher::PointPos curve2PosId = Sketcher::PointPos::none;

        double dist=INFINITY;

        const std::vector<Constraint *> &constraints = this->Constraints.getValues();

        for (std::vector<Constraint *>::const_iterator it=constraints.begin(); it != constraints.end(); ++it) {
            if ((*it)->Type == Sketcher::Coincident || (*it)->Type == Sketcher::Perpendicular || (*it)->Type == Sketcher::Tangent) {
                if ((*it)->First == GeoId1 && (*it)->Second == GeoId2 &&
                    (*it)->FirstPos != Sketcher::PointPos::none && (*it)->SecondPos != Sketcher::PointPos::none ) {
                    Base::Vector3d tmpp1 = getPoint((*it)->First,(*it)->FirstPos);
                    Base::Vector3d tmpp2 = getPoint((*it)->Second,(*it)->SecondPos);
                    double tmpdist = distancetorefpoints(tmpp1,
                                                         tmpp2,
                                                         refPnt1,
                                                         refPnt2);
                    if(tmpdist < dist) {
                        curve1PosId = (*it)->FirstPos;
                        curve2PosId = (*it)->SecondPos;
                        dist = tmpdist;
                        interpoints = std::make_pair(tmpp1,tmpp2);
                    }
                }
                else if ((*it)->First == GeoId2 && (*it)->Second == GeoId1 &&
                         (*it)->FirstPos != Sketcher::PointPos::none && (*it)->SecondPos != Sketcher::PointPos::none ) {
                    Base::Vector3d tmpp2 = getPoint((*it)->First,(*it)->FirstPos);
                    Base::Vector3d tmpp1 = getPoint((*it)->Second,(*it)->SecondPos);
                    double tmpdist = distancetorefpoints(tmpp1,
                                                         tmpp2,
                                                         refPnt1,
                                                         refPnt2);
                    if(tmpdist < dist) {
                        curve2PosId = (*it)->FirstPos;
                        curve1PosId = (*it)->SecondPos;
                        dist = tmpdist;
                        interpoints = std::make_pair(tmpp1,tmpp2);
                    }
                }
            }
        }

        if( curve1PosId == Sketcher::PointPos::none ) {
            // no coincident was found, try basis curve intersection if GeomTrimmedCurve
            if( geo1->isDerivedFrom(Part::GeomTrimmedCurve::getClassTypeId()) &&
                geo2->isDerivedFrom(Part::GeomTrimmedCurve::getClassTypeId())) {

                const Part::GeomTrimmedCurve *tcurve1 = static_cast<const Part::GeomTrimmedCurve*>(geo1);
                const Part::GeomTrimmedCurve *tcurve2 = static_cast<const Part::GeomTrimmedCurve*>(geo2);

                try {
                    if(!tcurve1->intersectBasisCurves(tcurve2,points))
                        return -1;
                }
                catch (Base::CADKernelError &e) {
                    e.ReportException();
                    THROWMT(Base::CADKernelError,QT_TRANSLATE_NOOP("Exceptions", "Unable to guess intersection of curves. Try adding a coincident constraint between the vertices of the curves you are intending to fillet."))
                }

                int res = selectintersection(points,interpoints,refPnt1, refPnt2);

                if (res != 0)
                    return res;
            }
            else
                return -1; // not a GeomTrimmedCurve and no coincident point.
        }

        // Now that we know where the curves intersect, get the parameters in the curves of those points
        double intparam1;
        double intparam2;

        try {
            if(!curve1->closestParameter(interpoints.first,intparam1))
                return -1;
        }
        catch (Base::CADKernelError &e) {
            e.ReportException();
            THROWM(Base::CADKernelError,"Unable to determine the parameter of the first selected curve at the intersection of the curves.")
        }

        try {
            if(!curve2->closestParameter(interpoints.second,intparam2))
                return -1;
        }
        catch (Base::CADKernelError &e) {
            e.ReportException();
            THROWM(Base::CADKernelError,"Unable to determine the parameter of the second selected curve at the intersection of the curves.")
        }

        // get the starting parameters of each curve
        double spc1 = curve1->getFirstParameter();
        double spc2 = curve2->getFirstParameter();

        // get a fillet radius if zero was given
        Base::Vector3d ref21 = refPnt2 - refPnt1;

        if (radius == .0f) {
            // guess a radius
            // https://forum.freecadweb.org/viewtopic.php?f=3&t=31594&start=50#p266658
            //
            // We do not know the actual tangency points until we intersect the offset curves, but
            // we do not have offset curves before with decide on a radius.
            //
            // This estimation guesses a radius as the average of the distances from the reference points
            // with respect to the intersection of the normals at those reference points.

            try {
                Base::Vector3d tdir1;
                Base::Vector3d tdir2;

                // We want normals, but OCCT normals require curves to be 2 times derivable, and lines are not
                // tangency calculation requires 1 time derivable.

                if(!curve1->tangent(refparam1, tdir1))
                    return -1;

                if(!curve2->tangent(refparam2, tdir2))
                    return -1;

                Base::Vector3d dir1(tdir1.y,-tdir1.x,0);
                Base::Vector3d dir2(tdir2.y,-tdir2.x,0);

                double det = -dir1.x*dir2.y + dir2.x*dir1.y;

                if (std::abs(det) < Precision::Confusion())
                    throw Base::RuntimeError("No intersection of normals"); // no intersection of normals

                Base::Vector3d refp1 = curve1->pointAtParameter(refparam1);
                Base::Vector3d refp2 = curve2->pointAtParameter(refparam2);

                //Base::Console().Log("refpoints: (%f,%f,%f);(%f,%f,%f)",refp1.x,refp1.y,refp1.z,refp2.x,refp2.y,refp2.z);

                Base::Vector3d normalintersect(
                    (-dir1.x*dir2.x*refp1.y + dir1.x*dir2.x*refp2.y - dir1.x*dir2.y*refp2.x + dir2.x*dir1.y*refp1.x)/det,
                    (-dir1.x*dir2.y*refp1.y + dir2.x*dir1.y*refp2.y + dir1.y*dir2.y*refp1.x - dir1.y*dir2.y*refp2.x)/det,0);

                radius = ((refp1 - normalintersect).Length() + (refp2 - normalintersect).Length())/2;
            }
            catch(const Base::Exception&) {
                radius = ref21.Length(); // fall-back to simplest estimation.
            }
        }


#ifdef DEBUG
        Base::Console().Log("Start param: (%f);(%f)\n",spc1,spc2);

        Base::Vector3d c1pf = curve1->pointAtParameter(spc1);
        Base::Vector3d c2pf = curve2->pointAtParameter(spc2);

        Base::Console().Log("start point curves: (%f,%f,%f);(%f,%f,%f)\n",c1pf.x,c1pf.y,c1pf.z,c2pf.x,c2pf.y,c2pf.z);
#endif
        // We create Offset curves at the suggested radius, the direction of offset is estimated from the tangency vector
        Base::Vector3d tdir1 = curve1->firstDerivativeAtParameter(refparam1);
        Base::Vector3d tdir2 = curve2->firstDerivativeAtParameter(refparam2);

#ifdef DEBUG
        Base::Console().Log("tangent vectors: (%f,%f,%f);(%f,%f,%f)\n",tdir1.x,tdir1.y,tdir1.z,tdir2.x,tdir2.y,tdir2.z);
        Base::Console().Log("inter-ref vector: (%f,%f,%f)\n",ref21.x,ref21.y,ref21.z);
#endif

        Base::Vector3d vn(0,0,1);

        double sdir1 = tdir1.Cross(ref21).Dot(vn);
        double sdir2 = tdir2.Cross(-ref21).Dot(vn);

#ifdef DEBUG
        Base::Console().Log("sign of offset: (%f,%f)\n",sdir1,sdir2);
        Base::Console().Log("radius: %f\n",radius);
#endif

        Part::GeomOffsetCurve * ocurve1 = new Part::GeomOffsetCurve(Handle(Geom_Curve)::DownCast(curve1->handle()), (sdir1<0)?radius:-radius, vn);

        Part::GeomOffsetCurve * ocurve2 = new Part::GeomOffsetCurve(Handle(Geom_Curve)::DownCast(curve2->handle()), (sdir2<0)?radius:-radius, vn);

#ifdef DEBUG
        Base::Vector3d oc1pf = ocurve1->pointAtParameter(ocurve1->getFirstParameter());
        Base::Vector3d oc2pf = ocurve2->pointAtParameter(ocurve2->getFirstParameter());

        Base::Console().Log("start point offset curves: (%f,%f,%f);(%f,%f,%f)\n",oc1pf.x,oc1pf.y,oc1pf.z,oc2pf.x,oc2pf.y,oc2pf.z);

        /*auto printoffsetcurve = [](Part::GeomOffsetCurve *c) {

            for(double param = c->getFirstParameter(); param < c->getLastParameter(); param = param + (c->getLastParameter()-c->getFirstParameter())/10)
                Base::Console().Log("\n%f: (%f,%f,0)\n", param, c->pointAtParameter(param).x,c->pointAtParameter(param).y);

        };

        printoffsetcurve(ocurve1);
        printoffsetcurve(ocurve2);*/
#endif

        // Next we calculate the intersection of offset curves to get the center of the fillet
        std::pair<Base::Vector3d, Base::Vector3d> filletcenterpoint;
        std::vector<std::pair<Base::Vector3d, Base::Vector3d>> offsetintersectionpoints;

        try {
            if(!ocurve1->intersect(ocurve2,offsetintersectionpoints)) {
#ifdef DEBUG
                Base::Console().Log("No intersection between offset curves\n");
#endif
                return -1;

            }
        }
        catch (Base::CADKernelError &e) {
            e.ReportException();
            THROWM(Base::CADKernelError,"Unable to find intersection between offset curves.")
        }

#ifdef DEBUG
        for(auto inter:offsetintersectionpoints) {
                Base::Console().Log("offset int(%f,%f,0)\n",inter.first.x,inter.first.y);
        }
#endif

        int res = selectintersection(offsetintersectionpoints,filletcenterpoint,refPnt1, refPnt2);

        if(res != 0)
            return res;

#ifdef DEBUG
        Base::Console().Log("selected offset int(%f,%f,0)\n",filletcenterpoint.first.x,filletcenterpoint.first.y);
#endif

        double refoparam1;
        double refoparam2;

        try {
            if(!curve1->closestParameter(filletcenterpoint.first,refoparam1))
                return -1;
        }
        catch (Base::CADKernelError &e) {
            e.ReportException();
            THROWM(Base::CADKernelError,"Unable to determine the starting point of the arc.")
        }

        try {
            if(!curve2->closestParameter(filletcenterpoint.second,refoparam2))
                return -1;
        }
        catch (Base::CADKernelError &e) {
            e.ReportException();
            THROWM(Base::CADKernelError,"Unable to determine the end point of the arc.")
        }

        // Next we calculate the closest points to the fillet center, so the points where tangency is to be applied
        Base::Vector3d refp1 = curve1->pointAtParameter(refoparam1);
        Base::Vector3d refp2 = curve2->pointAtParameter(refoparam2);

#ifdef DEBUG
        Base::Console().Log("refpoints: (%f,%f,%f);(%f,%f,%f)",refp1.x,refp1.y,refp1.z,refp2.x,refp2.y,refp2.z);
#endif
        // Now we create arc for the fillet
        double startAngle, endAngle, range;

        Base::Vector3d radDir1 = refp1 - filletcenterpoint.first;
        Base::Vector3d radDir2 = refp2 - filletcenterpoint.first;

        startAngle = atan2(radDir1.y, radDir1.x);

        range = atan2(-radDir1.y*radDir2.x+radDir1.x*radDir2.y,
                    radDir1.x*radDir2.x+radDir1.y*radDir2.y);

        endAngle = startAngle + range;

        if (endAngle < startAngle)
            std::swap(startAngle, endAngle);

        if (endAngle > 2*M_PI )
            endAngle -= 2*M_PI;

        if (startAngle < 0 )
            endAngle += 2*M_PI;

        // Create Arc Segment
        Part::GeomArcOfCircle *arc = new Part::GeomArcOfCircle();
        arc->setRadius(radDir1.Length());
        arc->setCenter(filletcenterpoint.first);
        arc->setRange(startAngle, endAngle, /*emulateCCWXY=*/true);

        // add arc to sketch geometry
        int filletId;
        Part::Geometry *newgeo = arc;
        filletId = addGeometry(newgeo);
        if (filletId < 0) {
            delete arc;
            return -1;
        }

        if (trim) {
            auto selectend = [](double intparam, double refparam, double startparam) {
                if( (intparam>refparam && startparam >= refparam) ||
                    (intparam<refparam && startparam <= refparam) ) {
                        return PointPos::start;
                }
                else {
                        return PointPos::end;
                }
            };

            // Two cases:
            // a) there as a coincidence constraint
            // b) we used the basis curve intersection


            if( curve1PosId == Sketcher::PointPos::none ) {
                curve1PosId = selectend(intparam1,refoparam1,spc1);
                curve2PosId = selectend(intparam2,refoparam2,spc2);
            }


            delConstraintOnPoint(GeoId1, curve1PosId, false);
            delConstraintOnPoint(GeoId2, curve2PosId, false);


            Sketcher::Constraint *tangent1 = new Sketcher::Constraint();
            Sketcher::Constraint *tangent2 = new Sketcher::Constraint();

            tangent1->Type = Sketcher::Tangent;
            tangent1->First = GeoId1;
            tangent1->FirstPos = curve1PosId;
            tangent1->Second = filletId;

            tangent2->Type = Sketcher::Tangent;
            tangent2->First = GeoId2;
            tangent2->FirstPos = curve2PosId;
            tangent2->Second = filletId;

            double dist1 = (refp1 - arc->getStartPoint(true)).Length();
            double dist2 = (refp1 - arc->getEndPoint(true)).Length();

            //Base::Console().Log("dists_refpoint_to_arc_sp_ep: (%f);(%f)",dist1,dist2);

            if (dist1 < dist2) {
                tangent1->SecondPos = PointPos::start;
                tangent2->SecondPos = PointPos::end;
                movePoint(GeoId1, curve1PosId, arc->getStartPoint(true),false,true);
                movePoint(GeoId2, curve2PosId, arc->getEndPoint(true),false,true);
            }
            else {
                tangent1->SecondPos = PointPos::end;
                tangent2->SecondPos = PointPos::start;
                movePoint(GeoId1, curve1PosId, arc->getEndPoint(true),false,true);
                movePoint(GeoId2, curve2PosId, arc->getStartPoint(true),false,true);
            }

            addConstraint(tangent1);
            addConstraint(tangent2);
            delete tangent1;
            delete tangent2;
        }
        delete arc;
        delete ocurve1;
        delete ocurve2;

#ifdef DEBUG
        Base::Console().Log("\n\nEND OF FILLET DEBUG\n\n");
#endif

        if(noRecomputes) // if we do not have a recompute after the geometry creation, the sketch must be solved to update the DoF of the solver
            solve();

        return 0;
    }
    return -1;
}

int SketchObject::extend(int GeoId, double increment, PointPos endpoint) {
    if (GeoId < 0 || GeoId > getHighestCurveIndex())
        return -1;

    const std::vector<Part::Geometry *> &geomList = getInternalGeometry();
    Part::Geometry *geom = geomList[GeoId];
    int retcode = -1;
    if (geom->getTypeId() == Part::GeomLineSegment::getClassTypeId()) {
        Part::GeomLineSegment *seg = static_cast<Part::GeomLineSegment *>(geom);
        Base::Vector3d startVec = seg->getStartPoint();
        Base::Vector3d endVec = seg->getEndPoint();
        if (endpoint == PointPos::start) {
            Base::Vector3d newPoint = startVec - endVec;
            double scaleFactor = newPoint.Length() + increment;
            newPoint.Normalize();
            newPoint.Scale(scaleFactor, scaleFactor, scaleFactor);
            newPoint = newPoint + endVec;
            retcode = movePoint(GeoId, Sketcher::PointPos::start, newPoint, false, true);
        } else if (endpoint == PointPos::end) {
            Base::Vector3d newPoint = endVec - startVec;
            double scaleFactor = newPoint.Length() + increment;
            newPoint.Normalize();
            newPoint.Scale(scaleFactor, scaleFactor, scaleFactor);
            newPoint = newPoint + startVec;
            retcode = movePoint(GeoId, Sketcher::PointPos::end, newPoint, false, true);
        }
    } else if (geom->getTypeId() == Part::GeomArcOfCircle::getClassTypeId()) {
        Part::GeomArcOfCircle *arc = static_cast<Part::GeomArcOfCircle *>(geom);
        double startArc, endArc;
        arc->getRange(startArc, endArc, true);
        if (endpoint == PointPos::start) {
            arc->setRange(startArc - increment, endArc, true);
            retcode = 0;
        } else if (endpoint == PointPos::end) {
            arc->setRange(startArc, endArc + increment, true);
            retcode = 0;
        }
    }
    if (retcode == 0 && noRecomputes) {
        solve();
    }
    return retcode;
}

std::unique_ptr<Constraint> SketchObject::createConstraint( Sketcher::ConstraintType constrType,
                                                            int firstGeoId,
                                                            Sketcher::PointPos firstPos,
                                                            int secondGeoId,
                                                            Sketcher::PointPos secondPos,
                                                            int thirdGeoId,
                                                            Sketcher::PointPos thirdPos)
{
    auto newConstr = std::make_unique<Sketcher::Constraint>();

    newConstr->Type = constrType;
    newConstr->First = firstGeoId;
    newConstr->FirstPos = firstPos;
    newConstr->Second = secondGeoId;
    newConstr->SecondPos = secondPos;
    newConstr->Third = thirdGeoId;
    newConstr->ThirdPos = thirdPos;
    return newConstr;
}

void SketchObject::addConstraint(Sketcher::ConstraintType constrType,
                                    int firstGeoId,
                                    Sketcher::PointPos firstPos,
                                    int secondGeoId,
                                    Sketcher::PointPos secondPos,
                                    int thirdGeoId,
                                    Sketcher::PointPos thirdPos)
{
    auto newConstr = createConstraint(constrType, firstGeoId, firstPos, secondGeoId, secondPos, thirdGeoId, thirdPos);

    this->addConstraint(std::move(newConstr));
}

bool SketchObject::seekTrimPoints(int GeoId, const Base::Vector3d &point,
                                  int &GeoId1, Base::Vector3d &intersect1,
                                  int &GeoId2, Base::Vector3d &intersect2)
{
    if (GeoId < 0 || GeoId > getHighestCurveIndex())
        return false;

    auto geos = getCompleteGeometry(); // this includes the axes too

    geos.resize(geos.size()-2); // remove the axes to avoid intersections with the axes

    int localindex1, localindex2;

    // Not found in will be returned as -1, not as GeoUndef, Part WB is agnostic to the concept of GeoUndef
    if(!Part2DObject::seekTrimPoints(geos, GeoId, point, localindex1, intersect1, localindex2, intersect2))
        return false;

    GeoId1 = getGeoIdFromCompleteGeometryIndex(localindex1); // invalid complete geometry indices are mapped to GeoUndef
    GeoId2 = getGeoIdFromCompleteGeometryIndex(localindex2);

    return true;
}

int SketchObject::trim(int GeoId, const Base::Vector3d& point)
{
    Base::StateLocker lock(managedoperation, true); // no need to check input data validity as this is an sketchobject managed operation.

    //******************* Basic checks rejecting the operation ****************************************//
    if (GeoId < 0 || GeoId > getHighestCurveIndex())
        return -1;

    auto geo = getGeometry(GeoId);

    if (!GeometryFacade::isInternalType(geo,InternalType::None))
        return -1; // internal alignment geometry is not trimmable

    //******************* Lambdas - common functions for different intersections ****************************************//

    // returns true if the point defined by (GeoId1, pos1) can be considered to be coincident with point.
    auto arePointsWithinPrecision = [] (Base::Vector3d point1, Base::Vector3d point2) {
        // From testing: 500x (or 0.000050) is needed in order to not falsely distinguish points calculated with seekTrimPoints
        if( (point1-point2).Length() < 500*Precision::Confusion())
            return true;

        return false;
    };

    auto isPointAtPosition = [this, arePointsWithinPrecision] (int GeoId1, PointPos pos1, Base::Vector3d point) {

        Base::Vector3d pp = getPoint(GeoId1,pos1);

        return arePointsWithinPrecision(point, pp);
    };

    // Helper function to remove Equal constraints from a chosen edge (e.g Line segment).
    auto delEqualConstraintsOnGeoId = [this] (int GeoId) {

        std::vector<int> delete_list;
        int index = 0;
        const std::vector<Constraint *> &constraints = this->Constraints.getValues();
        for (std::vector<Constraint *>::const_iterator it=constraints.begin();
                it != constraints.end(); ++it, ++index) {
            Constraint *constr = *(it);
            if (constr->First == GeoId && constr->Type == Sketcher::Equal) {
                delete_list.push_back(index);
            }
            if (constr->Second == GeoId && constr->Type == Sketcher::Equal) {
                delete_list.push_back(index);
            }
        }
        delConstraints(delete_list, false);
    };

    // Checks whether preexisting constraints must be converted to new constraints.
    // Preexisting point on object constraints get converted to coincidents, unless an end-to-end tangency is more relevant.
    // returns by reference:
    //      - The type of constraint that should be used to constraint GeoId1 and GeoId
    //      - The element of GeoId1 to which the constraint should be applied.
    auto transformPreexistingConstraints = [this, isPointAtPosition] (  int GeoId, int GeoId1, Base::Vector3d point1,
                                                                        ConstraintType &constrType, PointPos &secondPos ) {
        const std::vector<Constraint *> &constraints = this->Constraints.getValues();
        int constrId=0;
        std::vector<int> delete_list;
        for (std::vector<Constraint *>::const_iterator it=constraints.begin(); it != constraints.end(); ++it) {
            Constraint *constr = *(it);
            // There is a preexisting PointOnObject constraint, see if it must be converted to a coincident
            if (constr->Type == Sketcher::PointOnObject && constr->First == GeoId1  && constr->Second == GeoId) {
                if (isPointAtPosition(constr->First, constr->FirstPos, point1)) {
                    constrType = Sketcher::Coincident;
                    secondPos = constr->FirstPos;
                    delete_list.push_back(constrId);
                }
            }
            constrId++;
        }
        /* It is possible that the trimming entity has both a PointOnObject constraint to the trimmed entity, and a simple Tangent contstrait
         * to the trimmed entity. In this case we want to change to a single end-to-end tangency, i.e we want to ensure that constrType1 is
         * set to Sketcher::Tangent, that the secondPos1 is captured from the PointOnObject, and also make sure that the PointOnObject constraint
         * is deleted. The below loop ensures this, also in case the ordering of the constraints is first Tangent and then PointOnObject. */
        constrId=0;
        for (std::vector<Constraint *>::const_iterator it=constraints.begin(); it != constraints.end(); ++it) {
            Constraint *constr = *(it);
            if (constr->Type == Sketcher::Tangent) {
                if (constr->First == GeoId1 && constr->Second == GeoId) {
                    constrType = Sketcher::Tangent;
                    if (secondPos == Sketcher::PointPos::none)
                        secondPos = constr->FirstPos;
                    delete_list.push_back(constrId);
                } else if (constr->First == GeoId && constr->Second == GeoId1) {
                    constrType = Sketcher::Tangent;
                    if (secondPos == Sketcher::PointPos::none)
                        secondPos = constr->SecondPos;
                    delete_list.push_back(constrId);
                }
            }
            if (constr->Type == Sketcher::Perpendicular) {
                if (constr->First == GeoId1 && constr->Second == GeoId) {
                    constrType = Sketcher::Perpendicular;
                    if (secondPos == Sketcher::PointPos::none)
                        secondPos = constr->FirstPos;
                    delete_list.push_back(constrId);
                } else if (constr->First == GeoId && constr->Second == GeoId1) {
                    constrType = Sketcher::Perpendicular;
                    if (secondPos == Sketcher::PointPos::none)
                        secondPos = constr->SecondPos;
                    delete_list.push_back(constrId);
                }
            }

            constrId++;
        }
        delConstraints(delete_list, false);
    };

    // makes an equality constraint between GeoId1 and GeoId2
    auto constrainAsEqual = [this] (int GeoId1, int GeoId2) {
        auto newConstr = std::make_unique<Sketcher::Constraint>();

        // Build Constraints associated with new pair of arcs
        newConstr->Type = Sketcher::Equal;
        newConstr->First = GeoId1;
        newConstr->FirstPos = Sketcher::PointPos::none;
        newConstr->Second = GeoId2;
        newConstr->SecondPos = Sketcher::PointPos::none;
        addConstraint(std::move(newConstr));
    };

    // Removes all internal geometry of a BSplineCurve and updates the GeoId index after removal
    auto ifBSplineRemoveInternalAlignmentGeometry = [this](int &GeoId)
    {
        const Part::Geometry* geo = getGeometry(GeoId);
        if(geo->getTypeId() == Part::GeomBSplineCurve::getClassTypeId()) {
            // We need to remove the internal geometry of the BSpline, as BSplines change in number of poles and knots
            // We save the tags of the relevant geometry to retrieve the new GeoIds later on.
            boost::uuids::uuid GeoIdTag;

            GeoIdTag = geo->getTag();

            deleteUnusedInternalGeometry(GeoId);

            auto vals = getCompleteGeometry();

            for(size_t i = 0; i < vals.size(); i++) {
                if(vals[i]->getTag() == GeoIdTag) {
                    GeoId = getGeoIdFromCompleteGeometryIndex(i);
                    break;
                }

            }
        }
    };

    // given a geometry and tree points, returns the corresponding parameters of the geometry points closest to them
    auto getIntersectionParameters = [](const Part::Geometry * geo,
                                        const Base::Vector3d point, double &pointParam,
                                        const Base::Vector3d point1, double &point1Param,
                                        const Base::Vector3d point2, double &point2Param) {

        auto curve = static_cast<const Part::GeomCurve*>(geo);

        try {
           curve->closestParameter(point, pointParam);
           curve->closestParameter(point1, point1Param);
           curve->closestParameter(point2, point2Param);
        }
        catch(Base::CADKernelError & e) {
            e.ReportException();
            return false;
        }

        return true;
    };

    //******************* Step A => Detection of intersection - Common to all Geometries ****************************************//
    int GeoId1=GeoEnum::GeoUndef, GeoId2=GeoEnum::GeoUndef;
    Base::Vector3d point1, point2;
    // Using SketchObject wrapper, as Part2DObject version returns GeoId = -1 when intersection not found, which is wrong for a GeoId (axis).
    // seekTrimPoints returns:
    // - For a parameter associated with "point" between an intersection and the end point (non-periodic case) GeoId1 != GeoUndef and GeoId2 == GeoUndef
    // - For a parameter associated with "point" between the start point and an intersection (non-periodic case) GeoId2 != GeoUndef and GeoId1 == GeoUndef
    // - For a parameter associated with "point" between two intersection points, GeoId1 != GeoUndef and GeoId2 != GeoUndef
    //
    // FirstParam < point1param < point2param < LastParam
    if(!SketchObject::seekTrimPoints(GeoId, point, GeoId1, point1, GeoId2, point2)) {
        // If no suitable trim points are found, then trim defaults to deleting the geometry
        delGeometry(GeoId);
        return 0;
    }

    //******************* Preparation of BSplines ****************************************//
    // Trimmed B-Spline internal geometry cannot be reused
    geo = getGeometry(GeoId);

    auto isBSpline = geo->getTypeId() == Part::GeomBSplineCurve::getClassTypeId();
    auto isPeriodicBSpline = isBSpline && static_cast<const Part::GeomBSplineCurve *>(geo)->isPeriodic();
    auto isNonPeriodicBSpline = isBSpline && !static_cast<const Part::GeomBSplineCurve *>(geo)->isPeriodic();
    auto isLineSegment = geo->getTypeId() == Part::GeomLineSegment::getClassTypeId();
    auto isDerivedFromTrimmedCurve = geo->isDerivedFrom(Part::GeomTrimmedCurve::getClassTypeId());
    auto isCircle = geo->getTypeId() == Part::GeomCircle::getClassTypeId();
    auto isEllipse = geo->getTypeId() == Part::GeomEllipse::getClassTypeId();

    if(isBSpline) {

        // Two options, it is a periodic bspline and we need two intersections or
        // it is a non-periodic bspline and one intersection is enough.
        auto bspline = static_cast<const Part::GeomBSplineCurve *>(geo);

        if(bspline->isPeriodic() && (GeoId1 == GeoEnum::GeoUndef || GeoId2 == GeoEnum::GeoUndef))
            return -1;

        ifBSplineRemoveInternalAlignmentGeometry(GeoId); // GeoId gets updated here

        // When internal alignment geometry is removed from a bspline, it moves slightly
        // this causes that small segments are detected near the endpoints.
        //
        // The alternative to this re-detection, is to remove the internal alignment geometry
        // before the detection. However, that would cause the lost of the internal alignment geometry
        // in a case where trimming does not succeed because seekTrimPoints fails to find (suitable) intersection(s)
        if(!SketchObject::seekTrimPoints(GeoId, point, GeoId1, point1, GeoId2, point2)) {
            // If no suitable trim points are found, then trim defaults to deleting the geometry
            delGeometry(GeoId);
            return 0;
        }

        geo = getGeometry(GeoId);
    }

    if( GeoId1 != GeoEnum::GeoUndef &&
        GeoId2 != GeoEnum::GeoUndef &&
        arePointsWithinPrecision(point1, point2) ) { // If both points are detected and are coincident, deletion is the only option.
        delGeometry(GeoId);

        return 0;
    }

    //******************* Step B.1 => Trimming for GeomTrimmedCurves (line segment and arcs) ****************************************//
    if (isDerivedFromTrimmedCurve || isNonPeriodicBSpline ) {

        if(geo->isDerivedFrom(Part::GeomConic::getClassTypeId())) {
            auto *tc = static_cast<const Part::GeomConic*>(geo);
            if(tc->isReversed()) {
                const_cast<Part::GeomConic *>(tc)->reverse(); // reversing does not change the curve as seen by the sketcher.
            }
        }

        //****** Step B.1 (1) => Determine intersection parameters ******//
        // Now LastParam > FirstParam
        double firstParam, lastParam;
        if (isDerivedFromTrimmedCurve) {
            auto aoc = static_cast<const Part::GeomTrimmedCurve*>(geo);
            aoc->getRange(firstParam, lastParam);
        }
        else if(isNonPeriodicBSpline) {
            auto bsp = static_cast<const Part::GeomBSplineCurve*>(geo);
            firstParam = bsp->getFirstParameter();
            lastParam = bsp->getLastParameter();
        }

        double pointParam, point1Param, point2Param;
        if(!getIntersectionParameters(geo, point, pointParam, point1, point1Param, point2, point2Param))
            return -1;

#ifdef DEBUG
        Base::Console().Log("Trim sought: GeoId1=%d (%f), GeoId2=%d (%f)\n",GeoId1, point1Param, GeoId2, point2Param);
#endif

        // seekTrimPoints enforces that firstParam < point1Param < point2Param < lastParam
        auto paramDistance = [](double param1, double param2) {
            double distance = fabs(param1 - param2);

            if(distance < Precision::Confusion())
                return 0.;
            else
                return distance;
        };

        //****** Step B.1 (2) => Determine trimmable sections and trim operation ******//

        // Determine if there is something trimmable
        double startDistance = GeoId1 != GeoEnum::GeoUndef?paramDistance(firstParam, point1Param):paramDistance(firstParam, point2Param);
        double endDistance = GeoId2 != GeoEnum::GeoUndef?paramDistance(lastParam, point2Param):paramDistance(lastParam, point1Param);
        double middleDistance = (GeoId1 != GeoEnum::GeoUndef && GeoId2 != GeoEnum::GeoUndef)?paramDistance(point1Param, point2Param):0.0;

        bool trimmableStart = startDistance > 0.;
        bool trimmableMiddle = middleDistance > 0.;
        bool trimmableEnd = endDistance > 0.;

        struct Operation {
            Operation():Type(trim_none), actingParam(0.), intersectingGeoId(GeoEnum::GeoUndef){}
            enum {
                trim_none,
                trim_start,
                trim_middle,
                trim_end,
                trim_delete
            } Type;

            double actingParam;
            Base::Vector3d actingPoint;
            int intersectingGeoId;
        };

        Operation op;

        if ( GeoId1!=GeoEnum::GeoUndef &&
             GeoId2!=GeoEnum::GeoUndef &&
             pointParam > point1Param && pointParam < point2Param ) { // Trim Point between intersection points

            if( (!trimmableStart && !trimmableEnd) || !trimmableMiddle) { // if after trimming nothing would be left or if there is nothing to trim
                op.Type = Operation::trim_delete;
            }
            else if(trimmableStart && trimmableEnd) {
                op.Type = Operation::trim_middle; // trim between point1Param and point2Param
            }
            else if (trimmableStart /*&&!trimmableEnd*/) {
                op.Type = Operation::trim_end;
                op.actingParam = point1Param; // trim from point1Param until lastParam
                op.actingPoint = point1;
                op.intersectingGeoId = GeoId1;
            }
            else { // !trimmableStart && trimmableEnd
                op.Type = Operation::trim_start;
                op.actingParam = point2Param; // trim from firstParam until point2Param
                op.actingPoint = point2;
                op.intersectingGeoId = GeoId2;
            }
        }
        else if (GeoId2!=GeoEnum::GeoUndef && pointParam < point2Param) {
            if(trimmableEnd) {
                op.Type = Operation::trim_start;
                op.actingParam = point2Param; // trim from firstParam until point2Param
                op.actingPoint = point2;
                op.intersectingGeoId = GeoId2;
            }
            else {
                op.Type = Operation::trim_delete;
            }
        }
        else if (GeoId1!=GeoEnum::GeoUndef && pointParam > point1Param) {
            if(trimmableStart) {
                op.Type = Operation::trim_end;
                op.actingParam = point1Param; // trim from point1Param until lastParam
                op.actingPoint = point1;
                op.intersectingGeoId = GeoId1;
            }
            else {
                op.Type = Operation::trim_delete;
            }
        }
        else {
            return -1;
        }

        //****** Step B.1 (3) => Execute Trimming operation ******//

        if( op.Type == Operation::trim_delete) {
            delGeometry(GeoId);

            return 0;
        }
        else if ( op.Type == Operation::trim_middle ) {
            // We need to create new curve, this new curve will represent the segment comprising the end
            auto vals = getInternalGeometry();
            auto newVals(vals);
            newVals[GeoId] = newVals[GeoId]->clone();
            newVals.push_back(newVals[GeoId]->clone());
            int newGeoId = newVals.size() - 1;

            if (isDerivedFromTrimmedCurve) {
                static_cast<Part::GeomTrimmedCurve *>(newVals[GeoId])->setRange(firstParam, point1Param);
                static_cast<Part::GeomTrimmedCurve *>(newVals.back())->setRange(point2Param, lastParam);
            }
            else if(isNonPeriodicBSpline) {
                static_cast<Part::GeomBSplineCurve *>(newVals[GeoId])->Trim( firstParam, point1Param);
                static_cast<Part::GeomBSplineCurve *>(newVals.back())->Trim( point2Param, lastParam);
            }

            Geometry.setValues(std::move(newVals));

            // go through all constraints and replace the point (GeoId,end) with (newGeoId,end)
            transferConstraints(GeoId, PointPos::end, newGeoId, PointPos::end);

            // For a trimmed line segment, if it had an equality constraint, it must be removed as the segment length is not equal
            // For the rest of trimmed curves, the proportion shall be constrain to be equal.
            if(isLineSegment) {
                delEqualConstraintsOnGeoId(GeoId);
                delEqualConstraintsOnGeoId(newGeoId);
            }

            if(!isLineSegment && !isNonPeriodicBSpline) {
                constrainAsEqual(GeoId, newGeoId);
            }

            //****** Step B.1 (4) => Constraint end points of trim sections ******//

            // constrain the trimming points on the corresponding geometries
            PointPos secondPos1 = Sketcher::PointPos::none, secondPos2 = Sketcher::PointPos::none;
            ConstraintType constrType1 = Sketcher::PointOnObject, constrType2 = Sketcher::PointOnObject;

            // Segment comprising the start
            transformPreexistingConstraints (GeoId, GeoId1, point1, constrType1, secondPos1);

            addConstraint (constrType1, GeoId, Sketcher::PointPos::end, GeoId1, secondPos1);

            // Segment comprising the end
            transformPreexistingConstraints (GeoId, GeoId2, point2, constrType2, secondPos2);

            addConstraint (constrType2, newGeoId, Sketcher::PointPos::start, GeoId2, secondPos2);

            // Both segments have a coincident center
            if(!isLineSegment && !isBSpline) {
                addConstraint(Sketcher::Coincident, GeoId, Sketcher::PointPos::mid, newGeoId, Sketcher::PointPos::mid);
            }

            if (isNonPeriodicBSpline)
                exposeInternalGeometry(GeoId);

            if(noRecomputes) // if we do not have a recompute, the sketch must be solved to update the DoF of the solver
                solve();

            return 0;
        }
        else if (   op.Type == Operation::trim_start || op.Type == Operation::trim_end ) { // drop the second/first intersection point
            geo = getGeometry(GeoId);
            if (isDerivedFromTrimmedCurve) {
                auto newGeo = std::unique_ptr<Part::GeomTrimmedCurve>(static_cast<Part::GeomTrimmedCurve *>( geo->clone()));

                if (op.Type == Operation::trim_start)
                    newGeo->setRange( op.actingParam, lastParam);
                else if (op.Type == Operation::trim_end)
                    newGeo->setRange( firstParam, op.actingParam);

                Geometry.set1Value(GeoId, std::move(newGeo));
            }
            else if(isNonPeriodicBSpline) {
                auto newGeo = std::unique_ptr<Part::GeomBSplineCurve>(static_cast<Part::GeomBSplineCurve *>( geo->clone()));

                if (op.Type == Operation::trim_start)
                    newGeo->Trim( op.actingParam, lastParam);
                else if (op.Type == Operation::trim_end)
                    newGeo->Trim( firstParam, op.actingParam);

                Geometry.set1Value(GeoId, std::move(newGeo));
            }

            // After trimming it, a line segment won't have the same length
            if( isLineSegment) {
                delEqualConstraintsOnGeoId(GeoId);
            }

            //****** Step B.1 (4) => Constraint end points ******//
            ConstraintType constrType = Sketcher::PointOnObject; // So this is the fallback constraint type here.
            PointPos secondPos = Sketcher::PointPos::none;

            transformPreexistingConstraints (GeoId, op.intersectingGeoId, op.actingPoint, constrType, secondPos);

            if (op.Type == Operation::trim_start) {
                delConstraintOnPoint(GeoId, PointPos::start, false);
                // constrain the trimming point on the corresponding geometry
                addConstraint (constrType, GeoId, PointPos::start, op.intersectingGeoId, secondPos);
            }
            else if (op.Type == Operation::trim_end) {
                delConstraintOnPoint(GeoId, PointPos::end, false);
                // constrain the trimming point on the corresponding geometry
                addConstraint (constrType, GeoId, PointPos::end, op.intersectingGeoId, secondPos);
            }

            if (isNonPeriodicBSpline)
                exposeInternalGeometry(GeoId);

            if(noRecomputes) // if we do not have a recompute, the sketch must be solved to update the DoF of the solver
                solve();

            return 0;
        }
        else {
            return -1;
        }
    }
    //******************* Step B.2 => Trimming for unbounded periodic geometries ****************************************//
    else if ( isCircle || isEllipse || isPeriodicBSpline) {
        //****** STEP A(2) => Common tests *****//
        if( GeoId1==GeoEnum::GeoUndef || GeoId2==GeoEnum::GeoUndef)
            return -1;

        //****** Step B.2 (1) => Determine intersection parameters ******//
        double pointParam, point1Param, point2Param;
        if(!getIntersectionParameters(geo, point, pointParam, point1, point1Param, point2, point2Param))
            return -1;

#ifdef DEBUG
        Base::Console().Log("Trim sought: GeoId1=%d (%f), GeoId2=%d (%f)\n",GeoId1, point1Param, GeoId2, point2Param);
#endif

        //****** Step B.2 (3) => Execute Trimming operation ******//
        // Two intersection points detected
        std::unique_ptr<Part::Geometry> geoNew;

        if (isCircle) {
            auto circle = static_cast<const Part::GeomCircle*>(geo);
            auto aoc = std::make_unique<Part::GeomArcOfCircle>();
            aoc->setCenter(circle->getCenter());
            aoc->setRadius(circle->getRadius());
            aoc->setRange(point2Param, point1Param,/*emulateCCW=*/false);
            geoNew = std::move(aoc);
        }
        else if (isEllipse) {
            auto ellipse = static_cast<const Part::GeomEllipse*>(geo);
            auto aoe = std::make_unique<Part::GeomArcOfEllipse>();
            aoe->setCenter(ellipse->getCenter());
            aoe->setMajorRadius(ellipse->getMajorRadius());
            aoe->setMinorRadius(ellipse->getMinorRadius());
            aoe->setMajorAxisDir(ellipse->getMajorAxisDir());
            aoe->setRange(point2Param, point1Param,/*emulateCCW=*/false); // CCW curve goes from point2 (start) to point1 (end)
            geoNew = std::move( aoe );
        }
        else if (isPeriodicBSpline) {
            auto bspline = std::unique_ptr<Part::GeomBSplineCurve>(static_cast<Part::GeomBSplineCurve*>(geo->clone()));
            bspline->Trim(point2Param, point1Param);
            geoNew = std::move( bspline );
        }

        this->Geometry.set1Value(GeoId, std::move(geoNew));

        //****** Step B.2 (4) => Constraint end points ******//

        PointPos secondPos1 = Sketcher::PointPos::none, secondPos2 = Sketcher::PointPos::none;
        ConstraintType constrType1 = Sketcher::PointOnObject, constrType2 = Sketcher::PointOnObject;

        // check first if start and end points are within a confusion tolerance
        if(isPointAtPosition(GeoId1, Sketcher::PointPos::start, point1)) {
                constrType1 = Sketcher::Coincident;
                secondPos1 = Sketcher::PointPos::start;
        }
        else if(isPointAtPosition(GeoId1, Sketcher::PointPos::end, point1)) {
                constrType1 = Sketcher::Coincident;
                secondPos1 = Sketcher::PointPos::end;
        }

        if(isPointAtPosition(GeoId2, Sketcher::PointPos::start, point2)) {
                constrType2 = Sketcher::Coincident;
                secondPos2 = Sketcher::PointPos::start;
        }
        else if(isPointAtPosition(GeoId2, Sketcher::PointPos::end, point2)) {
                constrType2 = Sketcher::Coincident;
                secondPos2 = Sketcher::PointPos::end;
        }

        transformPreexistingConstraints (GeoId, GeoId1, point1, constrType1, secondPos1);
        transformPreexistingConstraints (GeoId, GeoId2, point2, constrType2, secondPos2);

        if( (constrType1 == Sketcher::Coincident && secondPos1 == Sketcher::PointPos::none) ||
            (constrType2 == Sketcher::Coincident && secondPos2 == Sketcher::PointPos::none))
            THROWM(ValueError,"Invalid position Sketcher::PointPos::none when creating a Coincident constraint")

        // constrain the trimming points on the corresponding geometries
        addConstraint (constrType1, GeoId, PointPos::end, GeoId1, secondPos1);

        addConstraint (constrType2, GeoId, PointPos::start, GeoId2, secondPos2);

        if (isBSpline)
            exposeInternalGeometry(GeoId);

        if(noRecomputes) // if we do not have a recompute, the sketch must be solved to update the DoF of the solver
            solve();

        return 0;
    }

    return -1;
}

int SketchObject::split(int GeoId, const Base::Vector3d &point)
{
    // No need to check input data validity as this is an sketchobject managed operation

    Base::StateLocker lock(managedoperation, true);

    if (GeoId < 0 || GeoId > getHighestCurveIndex()) {
        return -1;
    }

    const Part::Geometry *geo = getGeometry(GeoId);
    std::vector<int> newIds;
    std::vector<Constraint *> newConstraints;

    Base::Vector3d startPoint, endPoint, splitPoint;
    double startParam, endParam, splitParam=0.0;
    unsigned int longestPart = 0;

    auto createGeosFromPeriodic =
        [&](const Part::GeomCurve* curve,
            auto getCurveWithLimitParams,
            auto createAndTransferConstraints) {
            // find split point
            curve->closestParameter(point, splitParam);
            double period = curve->getLastParameter() - curve->getFirstParameter();
            startParam = splitParam;
            endParam = splitParam + period;

            // create new arc and restrict it
            auto newCurve = getCurveWithLimitParams(curve, startParam, endParam);
            int newId(GeoEnum::GeoUndef);
            newId = addGeometry(std::move(newCurve)); // after here newCurve is a shell
            if (newId >= 0) {
                newIds.push_back(newId);
                setConstruction(newId, GeometryFacade::getConstruction(curve));
                exposeInternalGeometry(newId);

                // transfer any constraints
                createAndTransferConstraints(GeoId, newId);
                return true;
            }

            return false;
        };

    auto createGeosFromNonPeriodic =
        [&](const Part::GeomBoundedCurve* curve,
            auto getCurveWithLimitParams,
            auto createAndTransferConstraints) {
            startPoint = curve->getStartPoint();
            endPoint = curve->getEndPoint();

            // find split point
            curve->closestParameter(point, splitParam);
            startParam = curve->getFirstParameter();
            endParam = curve->getLastParameter();
            // TODO: Using parameter difference as a poor substitute of length.
            // Computing length of an arc of a generic conic would be expensive.
            if (endParam - splitParam < Precision::PConfusion() ||
                splitParam - startParam < Precision::PConfusion()) {
                THROWM(ValueError, "Split point is at one of the end points of the curve.");
            }
            if (endParam - splitParam > splitParam - startParam) {
                longestPart = 1;
            }

            // create new curves
            auto newCurve = getCurveWithLimitParams(curve, startParam, splitParam);
            int newId(GeoEnum::GeoUndef);
            newId = addGeometry(std::move(newCurve));
            if (newId >= 0) {
                newIds.push_back(newId);
                setConstruction(newId, GeometryFacade::getConstruction(curve));
                exposeInternalGeometry(newId);

                // the "second" half
                newCurve = getCurveWithLimitParams(curve, splitParam, endParam);
                newId = addGeometry(std::move(newCurve));
                if (newId >= 0) {
                    newIds.push_back(newId);
                    setConstruction(newId, GeometryFacade::getConstruction(curve));
                    exposeInternalGeometry(newId);

                    // TODO: Certain transfers and new constraint can be directly made here.
                    // But this may reduce readability.
                    // apply appropriate constraints on the new points at split point and
                    // transfer constraints from start and end of original spline
                    createAndTransferConstraints(GeoId, newIds[0], newIds[1]);
                    return true;
                }
            }

            return false;
        };

    bool ok = false;
    if (geo->getTypeId() == Part::GeomLineSegment::getClassTypeId()) {
        ok = createGeosFromNonPeriodic(
            static_cast<const Part::GeomBoundedCurve *>(geo),
            [](const Part::GeomCurve* curve, double startParam, double endParam) {
                auto newArc = std::unique_ptr<Part::GeomLineSegment>(static_cast<Part::GeomLineSegment *>(curve->copy()));
                newArc->setRange(startParam, endParam);
                return newArc;
            },
            [this, &newConstraints](int GeoId, int newId0, int newId1) {
                Constraint* joint = new Constraint();
                joint->Type = Coincident;
                joint->First = newId0;
                joint->FirstPos = PointPos::end;
                joint->Second = newId1;
                joint->SecondPos = PointPos::start;
                newConstraints.push_back(joint);

                transferConstraints(GeoId, PointPos::start, newId0, PointPos::start);
                transferConstraints(GeoId, PointPos::end, newId1, PointPos::end);
            });
    }
    else if (geo->getTypeId() == Part::GeomCircle::getClassTypeId()) {
        ok = createGeosFromPeriodic(
            static_cast<const Part::GeomCurve *>(geo),
            [](const Part::GeomCurve* curve, double startParam, double endParam) {
                auto newArc = std::make_unique<Part::GeomArcOfCircle>(Handle(Geom_Circle)::DownCast(curve->handle()->Copy()));
                newArc->setRange(startParam, endParam, false);
                return newArc;
            },
            [this](int GeoId, int newId) {
                transferConstraints(GeoId, PointPos::mid, newId, PointPos::mid);
            });
    }
    else if (geo->getTypeId() == Part::GeomEllipse::getClassTypeId()) {
        ok = createGeosFromPeriodic(
            static_cast<const Part::GeomCurve *>(geo),
            [](const Part::GeomCurve* curve, double startParam, double endParam) {
                auto newArc = std::make_unique<Part::GeomArcOfEllipse>(Handle(Geom_Ellipse)::DownCast(curve->handle()->Copy()));
                newArc->setRange(startParam, endParam, false);
                return newArc;
            },
            [this](int GeoId, int newId) {
                transferConstraints(GeoId, PointPos::mid, newId, PointPos::mid);
            });
    }
    else if (geo->getTypeId() == Part::GeomArcOfCircle::getClassTypeId()) {
        ok = createGeosFromNonPeriodic(
            static_cast<const Part::GeomBoundedCurve *>(geo),
            [](const Part::GeomCurve* curve, double startParam, double endParam) {
                auto newArc = std::unique_ptr<Part::GeomArcOfCircle>(static_cast<Part::GeomArcOfCircle *>(curve->copy()));
                newArc->setRange(startParam, endParam, false);
                return newArc;
            },
            [this, &newConstraints](int GeoId, int newId0, int newId1) {
                Constraint* joint = new Constraint();
                joint->Type = Coincident;
                joint->First = newId0;
                joint->FirstPos = PointPos::end;
                joint->Second = newId1;
                joint->SecondPos = PointPos::start;
                newConstraints.push_back(joint);

                joint = new Constraint();
                joint->Type = Coincident;
                joint->First = newId0;
                joint->FirstPos = PointPos::mid;
                joint->Second = newId1;
                joint->SecondPos = PointPos::mid;
                newConstraints.push_back(joint);

                transferConstraints(GeoId, PointPos::start, newId0, PointPos::start, true);
                transferConstraints(GeoId, PointPos::mid, newId0, PointPos::mid);
                transferConstraints(GeoId, PointPos::end, newId1, PointPos::end, true);
            });
    }
    else if (geo->isDerivedFrom(Part::GeomArcOfConic::getClassTypeId())) {
        ok = createGeosFromNonPeriodic(
            static_cast<const Part::GeomBoundedCurve *>(geo),
            [](const Part::GeomCurve* curve, double startParam, double endParam) {
                auto newArc = std::unique_ptr<Part::GeomArcOfConic>(static_cast<Part::GeomArcOfConic *>(curve->copy()));
                newArc->setRange(startParam, endParam);
                return newArc;
            },
            [this, &newConstraints](int GeoId, int newId0, int newId1) {
                // apply appropriate constraints on the new points at split point
                Constraint* joint = new Constraint();
                joint->Type = Coincident;
                joint->First = newId0;
                joint->FirstPos = PointPos::end;
                joint->Second = newId1;
                joint->SecondPos = PointPos::start;
                newConstraints.push_back(joint);

                // TODO: Do we apply constraints on center etc of the conics?

                // transfer constraints from start and end of original
                transferConstraints(GeoId, PointPos::start, newId0, PointPos::start, true);
                transferConstraints(GeoId, PointPos::end, newId1, PointPos::end, true);
            });
    }
    else if (geo->getTypeId() == Part::GeomBSplineCurve::getClassTypeId()) {
        const Part::GeomBSplineCurve *bsp = static_cast<const Part::GeomBSplineCurve *>(geo);

        // what to do for periodic b-splines?
        if (bsp->isPeriodic()) {
            ok = createGeosFromPeriodic(
                static_cast<const Part::GeomCurve *>(geo),
                [](const Part::GeomCurve* curve, double startParam, double endParam) {
                    auto newBsp = std::unique_ptr<Part::GeomBSplineCurve>(static_cast<Part::GeomBSplineCurve *>(curve->copy()));
                    newBsp->Trim(startParam, endParam);
                    return newBsp;
                },
                [](int, int) {
                    // no constraints to transfer here, and we assume the split is to "break" the b-spline
                });
        }
        else {
            ok = createGeosFromNonPeriodic(
                static_cast<const Part::GeomBoundedCurve *>(geo),
                [](const Part::GeomCurve* curve, double startParam, double endParam) {
                    auto newBsp = std::unique_ptr<Part::GeomBSplineCurve>(static_cast<Part::GeomBSplineCurve *>(curve->copy()));
                    newBsp->Trim(startParam, endParam);
                    return newBsp;
                },
                [this, &newConstraints](int GeoId, int newId0, int newId1) {
                    // apply appropriate constraints on the new points at split point
                    Constraint* joint = new Constraint();
                    joint->Type = Coincident;
                    joint->First = newId0;
                    joint->FirstPos = PointPos::end;
                    joint->Second = newId1;
                    joint->SecondPos = PointPos::start;
                    newConstraints.push_back(joint);

                    // transfer constraints from start and end of original spline
                    transferConstraints(GeoId, PointPos::start, newId0, PointPos::start, true);
                    transferConstraints(GeoId, PointPos::end, newId1, PointPos::end, true);
                });
        }
    }

    if (ok) {
        std::vector<int> oldConstraints;
        getConstraintIndices(GeoId, oldConstraints);

        const auto& allConstraints = this->Constraints.getValues();

        // keep constraints on internal geometries so they are deleted
        // when the old curve is deleted
        oldConstraints.erase(
            std::remove_if(
                oldConstraints.begin(), oldConstraints.end(),
                [=](const auto& i){return allConstraints[i]->Type == InternalAlignment;}),
            oldConstraints.end());

        for (unsigned int i = 0; i < oldConstraints.size(); ++i) {

            Constraint *con = allConstraints[oldConstraints[i]];
            int conId = con->First;
            PointPos conPos = con->FirstPos;
            if (conId == GeoId) {
                conId = con->Second;
                conPos = con->SecondPos;
            }

            bool transferToAll = false;
            switch (con->Type) {
            case Horizontal:
            case Vertical:
            case Parallel: {
                transferToAll = geo->getTypeId() == Part::GeomLineSegment::getClassTypeId();
                break;
            }
            case Tangent:
            case Perpendicular: {
                unsigned int initial = 0;
                unsigned int limit = newIds.size();

                if (geo->isDerivedFrom(Part::GeomArcOfConic::getClassTypeId())) {
                    const Part::Geometry *conGeo = getGeometry(conId);

                    if (conGeo && conGeo->isDerivedFrom(Part::GeomCurve::getClassTypeId())){
                        std::vector<std::pair<Base::Vector3d, Base::Vector3d>> intersections;
                        bool intersects[2];
                        auto *geo1 = getGeometry(newIds[0]);
                        auto *geo2 = getGeometry(newIds[1]);

                        intersects[0] = static_cast<const Part::GeomCurve *>(geo1)->
                            intersect(static_cast<const Part::GeomCurve *>(conGeo), intersections);
                        intersects[1] = static_cast<const Part::GeomCurve *>(geo2)->
                            intersect(static_cast<const Part::GeomCurve *>(conGeo), intersections);

                        initial = longestPart;
                        if (intersects[0] != intersects[1]) {
                            initial = intersects[1] ? 1 : 0;
                        }
                        limit = initial + 1;
                    }
                }

                for (unsigned int i = initial; i < limit; ++i) {
                    Constraint *trans = con->copy();
                    trans->substituteIndex(GeoId, newIds[i]);
                    newConstraints.push_back(trans);
                }
                break;
            }
            case Distance:
            case DistanceX:
            case DistanceY:
            case PointOnObject: {
                if (con->FirstPos == PointPos::none && con->SecondPos == PointPos::none) {
                    Constraint *dist = con->copy();
                    dist->First = newIds[0];
                    dist->FirstPos = PointPos::start;
                    dist->Second = newIds[1];
                    dist->SecondPos = PointPos::end;
                    newConstraints.push_back(dist);
                }
                else {
                    Constraint *trans = con->copy();
                    trans->First = conId;
                    trans->FirstPos = conPos;
                    trans->SecondPos = PointPos::none;

                    Base::Vector3d conPoint(getPoint(conId, conPos));
                    int targetId = newIds[0];

                    // for non-periodic curves, see if second curve is more appropriate
                    if (geo->getTypeId() == Part::GeomLineSegment::getClassTypeId()) {
                        Base::Vector3d projPoint(conPoint.Perpendicular(startPoint, endPoint - startPoint));
                        Base::Vector3d splitDir = splitPoint - startPoint;
                        if ((projPoint - startPoint)*splitDir > splitDir*splitDir) {
                            targetId = newIds[1];
                        }
                    }
                    else if (geo->isDerivedFrom(Part::GeomArcOfConic::getClassTypeId())) {
                        double conParam;
                        static_cast<const Part::GeomArcOfConic*>(geo)->closestParameter(conPoint, conParam);
                        if (conParam > splitParam)
                            targetId = newIds[1];
                    }
                    trans->Second = targetId;

                    newConstraints.push_back(trans);
                }
                break;
            }
            case Radius:
            case Diameter:
            case Equal: {
                transferToAll = geo->getTypeId() == Part::GeomCircle::getClassTypeId()
                    || geo->getTypeId() == Part::GeomArcOfCircle::getClassTypeId();
                break;
            }
            default:
                // Release other constraints
                break;
            }

            if (transferToAll) {
                for (auto& newId: newIds) {
                    Constraint *trans = con->copy();
                    trans->substituteIndex(GeoId, newId);
                    newConstraints.push_back(trans);
                }
            }
        }

        if (noRecomputes)
            solve();

        delConstraints(oldConstraints);
        addConstraints(newConstraints);
    }

    for (auto& cons: newConstraints) {
        delete cons;
    }

    if (ok) {
        delGeometry(GeoId);
        return 0;
    }

    return -1;
}

int SketchObject::join(int geoId1, Sketcher::PointPos posId1,
                       int geoId2, Sketcher::PointPos posId2)
{
    // No need to check input data validity as this is an sketchobject managed operation

    Base::StateLocker lock(managedoperation, true);

    if (Sketcher::PointPos::start != posId1 && Sketcher::PointPos::end != posId1 &&
        Sketcher::PointPos::start != posId2 && Sketcher::PointPos::end != posId2) {
        THROWM(ValueError,"Invalid position(s): points must be start or end points of a curve.");
        return -1;
    }

    if (geoId1 == geoId2) {
        THROWM(ValueError,"Connecting the end points of the same curve is not yet supported.");
        return -1;
    }

    if (geoId1 < 0 || geoId1 > getHighestCurveIndex() ||
        geoId2 < 0 || geoId2 > getHighestCurveIndex()) {
        return -1;
    }

    // get the old splines
    auto* geo1 = dynamic_cast<const Part::GeomCurve *>(getGeometry(geoId1));
    auto* geo2 = dynamic_cast<const Part::GeomCurve *>(getGeometry(geoId2));

    if (GeometryFacade::getConstruction(geo1) != GeometryFacade::getConstruction(geo2)) {
        THROWM(ValueError,"Cannot join construction and non-construction geometries.");
        return -1;
    }

    // TODO: make both curves b-splines here itself
    if (!geo1 || !geo2) {
        return -1;
    }

    // TODO: is there a cleaner way to get our mutable bsp's?
    // we need the splines to be mutable because we may reverse them
    // and/or change their degree
    std::unique_ptr<Part::GeomBSplineCurve> bsp1(geo1->toNurbs(geo1->getFirstParameter(), geo1->getLastParameter()));
    std::unique_ptr<Part::GeomBSplineCurve> bsp2(geo2->toNurbs(geo2->getFirstParameter(), geo2->getLastParameter()));

    if (bsp1->isPeriodic() || bsp2->isPeriodic()) {
        THROWM(ValueError,"It is only possible to join non-periodic curves.");
        return -1;
    }

    // reverse the splines if needed: join end of 1st to start of 2nd
    if (Sketcher::PointPos::start == posId1)
        bsp1->reverse();
    if (Sketcher::PointPos::end == posId2)
        bsp2->reverse();

    // ensure the degrees of both curves are the same
    if (bsp1->getDegree() < bsp2->getDegree())
        bsp1->increaseDegree(bsp2->getDegree());
    else if (bsp2->getDegree() < bsp1->getDegree())
        bsp2->increaseDegree(bsp1->getDegree());

    // TODO: set up vectors for new poles, knots, mults
    std::vector<Base::Vector3d> poles1 = bsp1->getPoles();
    std::vector<double> weights1 = bsp1->getWeights();
    std::vector<double> knots1 = bsp1->getKnots();
    std::vector<int> mults1 = bsp1->getMultiplicities();
    std::vector<Base::Vector3d> poles2 = bsp2->getPoles();
    std::vector<double> weights2 = bsp2->getWeights();
    std::vector<double> knots2 = bsp2->getKnots();
    std::vector<int> mults2 = bsp2->getMultiplicities();

    std::vector<Base::Vector3d> newPoles(std::move(poles1));
    std::vector<double> newWeights(std::move(weights1));
    std::vector<double> newKnots(std::move(knots1));
    std::vector<int> newMults(std::move(mults1));

    poles2.erase(poles2.begin());
    newPoles.insert(newPoles.end(),
                    std::make_move_iterator(poles2.begin()),
                    std::make_move_iterator(poles2.end()));

    // TODO: Weights might need to be scaled
    weights2.erase(weights2.begin());
    newWeights.insert(newWeights.end(),
                      std::make_move_iterator(weights2.begin()),
                      std::make_move_iterator(weights2.end()));

    // knots of the second spline come after all of the first
    double offset = newKnots.back() - knots2.front();
    knots2.erase(knots2.begin());
    for (auto& knot : knots2)
        knot += offset;
    newKnots.insert(newKnots.end(),
                    std::make_move_iterator(knots2.begin()),
                    std::make_move_iterator(knots2.end()));

    // end knots can have a multiplicity of (degree + 1)
    if (bsp1->getDegree() < newMults.back())
        newMults.back() = bsp1->getDegree();
    mults2.erase(mults2.begin());
    newMults.insert(newMults.end(),
                    std::make_move_iterator(mults2.begin()),
                    std::make_move_iterator(mults2.end()));

    Part::GeomBSplineCurve* newSpline =
        new Part::GeomBSplineCurve(newPoles, newWeights, newKnots, newMults,
                                   bsp1->getDegree(), false, true);

    int newGeoId = addGeometry(newSpline);

    if (newGeoId < 0) {
        THROWM(ValueError,"Failed to create joined curve.");
        return -1;
    }
    else {
        exposeInternalGeometry(newGeoId);
        setConstruction(newGeoId, GeometryFacade::getConstruction(geo1));

        // TODO: transfer constraints on the non-connected ends
        auto otherPosId1 = (Sketcher::PointPos::start == posId1) ? Sketcher::PointPos::end : Sketcher::PointPos::start;
        auto otherPosId2 = (Sketcher::PointPos::start == posId2) ? Sketcher::PointPos::end : Sketcher::PointPos::start;

        transferConstraints(geoId1, otherPosId1, newGeoId, PointPos::start, true);
        transferConstraints(geoId2, otherPosId2, newGeoId, PointPos::end, true);

        delGeometries({geoId1, geoId2});
        return 0;
    }

    return -1;
}

bool SketchObject::isExternalAllowed(App::Document *pDoc, App::DocumentObject *pObj, eReasonList* rsn) const
{
    if (rsn)
        *rsn = rlAllowed;

    // Externals outside of the Document are NOT allowed
    if (this->getDocument() != pDoc){
        if (rsn)
            *rsn = rlOtherDoc;
        return false;
    }

    //circular reference prevention
    try {
        if (!(this->testIfLinkDAGCompatible(pObj))){
            if (rsn)
                *rsn = rlCircularReference;
            return false;
        }
    } catch (Base::Exception &e) {
        Base::Console().Warning("Probably, there is a circular reference in the document. Error: %s\n", e.what());
        return true; //prohibiting this reference won't remove the problem anyway...
    }


    // Note: Checking for the body of the support doesn't work when the support are the three base planes
    //App::DocumentObject *support = this->Support.getValue();
    Part::BodyBase* body_this = Part::BodyBase::findBodyOf(this);
    Part::BodyBase* body_obj = Part::BodyBase::findBodyOf(pObj);
    App::Part* part_this = App::Part::getPartOfObject(this);
    App::Part* part_obj = App::Part::getPartOfObject(pObj);
    if (part_this == part_obj){ //either in the same part, or in the root of document
        if (!body_this) {
            return true;
        } else if (body_this == body_obj) {
            return true;
        } else {
            if (rsn)
                *rsn = rlOtherBody;
            return false;
        }
    }
    else {
        // cross-part link. Disallow, should be done via shapebinders only
        if (rsn)
            *rsn = rlOtherPart;
        return false;
    }
}

bool SketchObject::isCarbonCopyAllowed(App::Document *pDoc, App::DocumentObject *pObj, bool & xinv, bool & yinv, eReasonList* rsn) const
{
    if (rsn)
        *rsn = rlAllowed;

    // Only applicable to sketches
    if (pObj->getTypeId() != Sketcher::SketchObject::getClassTypeId()) {
        if (rsn)
            *rsn = rlNotASketch;
        return false;
    }

    SketchObject * psObj = static_cast<SketchObject *>(pObj);

    // Sketches outside of the Document are NOT allowed
    if (this->getDocument() != pDoc){
        if (rsn)
            *rsn = rlOtherDoc;
        return false;
    }

    //circular reference prevention
    try {
        if (!(this->testIfLinkDAGCompatible(pObj))){
            if (rsn)
                *rsn = rlCircularReference;
            return false;
        }
    } catch (Base::Exception &e) {
        Base::Console().Warning("Probably, there is a circular reference in the document. Error: %s\n", e.what());
        return true; //prohibiting this reference won't remove the problem anyway...
    }


    // Note: Checking for the body of the support doesn't work when the support are the three base planes
    //App::DocumentObject *support = this->Support.getValue();
    Part::BodyBase* body_this = Part::BodyBase::findBodyOf(this);
    Part::BodyBase* body_obj = Part::BodyBase::findBodyOf(pObj);
    App::Part* part_this = App::Part::getPartOfObject(this);
    App::Part* part_obj = App::Part::getPartOfObject(pObj);
    if (part_this == part_obj){ //either in the same part, or in the root of document
        if (body_this) {
            if (body_this != body_obj) {
                if (!this->allowOtherBody) {
                    if (rsn)
                        *rsn = rlOtherBody;
                    return false;
                }
                else if (psObj->getExternalGeometryCount()>2){ // if the original sketch has external geometry AND it is not in this body prevent link
                    if (rsn)
                        *rsn = rlOtherBodyWithLinks;
                    return false;
                }
            }
        }
    } else {
        // cross-part relation. Disallow, should be done via shapebinders only
        if (rsn)
            *rsn = rlOtherPart;
        return false;
    }



    const Rotation & srot = psObj->Placement.getValue().getRotation();
    const Rotation & lrot = this->Placement.getValue().getRotation();

    Base::Vector3d snormal(0,0,1);
    Base::Vector3d sx(1,0,0);
    Base::Vector3d sy(0,1,0);
    srot.multVec(snormal, snormal);
    srot.multVec(sx, sx);
    srot.multVec(sy, sy);

    Base::Vector3d lnormal(0,0,1);
    Base::Vector3d lx(1,0,0);
    Base::Vector3d ly(0,1,0);
    lrot.multVec(lnormal, lnormal);
    lrot.multVec(lx, lx);
    lrot.multVec(ly, ly);

    double dot = snormal*lnormal;
    double dotx = sx * lx;
    double doty = sy * ly;

    // the planes of the sketches must be parallel
    if(!allowUnaligned && fabs(fabs(dot)-1) > Precision::Confusion()) {
        if (rsn)
            *rsn = rlNonParallel;
        return false;
    }

    // the axis must be aligned
    if(!allowUnaligned && ((fabs(fabs(dotx)-1) > Precision::Confusion()) || (fabs(fabs(doty)-1) > Precision::Confusion()))) {
        if (rsn)
            *rsn = rlAxesMisaligned;
        return false;
    }


    // the origins of the sketches must be aligned or be the same
    Base::Vector3d ddir = (psObj->Placement.getValue().getPosition() - this->Placement.getValue().getPosition()).Normalize();

    double alignment = ddir * lnormal;

    if(!allowUnaligned && (fabs(fabs(alignment)-1) > Precision::Confusion()) && (psObj->Placement.getValue().getPosition() != this->Placement.getValue().getPosition()) ){
        if (rsn)
            *rsn = rlOriginsMisaligned;
        return false;
    }

    xinv = allowUnaligned?false:(fabs(dotx-1) > Precision::Confusion());
    yinv = allowUnaligned?false:(fabs(doty-1) > Precision::Confusion());

    return true;
}

int SketchObject::addSymmetric(const std::vector<int> &geoIdList, int refGeoId, Sketcher::PointPos refPosId/*=Sketcher::PointPos::none*/)
{
    Base::StateLocker lock(managedoperation, true); // no need to check input data validity as this is an sketchobject managed operation.

    const std::vector< Part::Geometry * > &geovals = getInternalGeometry();
    std::vector< Part::Geometry * > newgeoVals(geovals);

    const std::vector< Constraint * > &constrvals = this->Constraints.getValues();
    std::vector< Constraint * > newconstrVals(constrvals);

    newgeoVals.reserve(geovals.size()+geoIdList.size());

    int cgeoid = getHighestCurveIndex()+1;

    std::map<int, int> geoIdMap;
    std::map<int, bool> isStartEndInverted;

    // Find out if reference is aligned with V or H axis,
    // if so we can keep Vertical and Horizontal constraints in the mirrored geometry.
    bool refIsAxisAligned = false;
    if (refGeoId == Sketcher::GeoEnum::VAxis || refGeoId == Sketcher::GeoEnum::HAxis) {
        refIsAxisAligned = true;
    } else {
        for (std::vector<Constraint *>::const_iterator it = constrvals.begin(); it != constrvals.end(); ++it) {
            Constraint *constr = *(it);
            if (constr->First == refGeoId && (constr->Type == Sketcher::Vertical || constr->Type == Sketcher::Horizontal))
                refIsAxisAligned = true;
        }
    }

    // reference is a line
    if(refPosId == Sketcher::PointPos::none) {
        const Part::Geometry *georef = getGeometry(refGeoId);
        if(georef->getTypeId() != Part::GeomLineSegment::getClassTypeId()) {
            Base::Console().Error("Reference for symmetric is neither a point nor a line.\n");
            return -1;
        }

        const Part::GeomLineSegment *refGeoLine = static_cast<const Part::GeomLineSegment *>(georef);
        //line
        Base::Vector3d refstart = refGeoLine->getStartPoint();
        Base::Vector3d vectline = refGeoLine->getEndPoint()-refstart;

        for (std::vector<int>::const_iterator it = geoIdList.begin(); it != geoIdList.end(); ++it) {
            const Part::Geometry *geo = getGeometry(*it);
            Part::Geometry *geosym;

            auto gf = GeometryFacade::getFacade(geo);

            if(gf->isInternalAligned()) {
                // only add this geometry if the corresponding geometry it defines is also in the list.
                int definedGeo = GeoEnum::GeoUndef;

                for( auto c : Constraints.getValues()) {
                    if(c->Type == Sketcher::InternalAlignment && c->First == *it) {
                        definedGeo = c->Second;
                        break;
                    }
                }

                if(std::find(geoIdList.begin(), geoIdList.end(), definedGeo) != geoIdList.end() )
                    geosym = geo->copy();
                else
                    continue; // we should not mirror internal alignment geometry, unless the element they define is also mirrored

            }
            else {
                geosym = geo->copy();
            }

            // Handle Geometry
            if(geosym->getTypeId() == Part::GeomLineSegment::getClassTypeId()){
                Part::GeomLineSegment *geosymline = static_cast<Part::GeomLineSegment *>(geosym);
                Base::Vector3d sp = geosymline->getStartPoint();
                Base::Vector3d ep = geosymline->getEndPoint();

                geosymline->setPoints(sp+2.0*(sp.Perpendicular(refGeoLine->getStartPoint(),vectline)-sp),
                        ep+2.0*(ep.Perpendicular(refGeoLine->getStartPoint(),vectline)-ep));
                isStartEndInverted.insert(std::make_pair(*it, false));
            }
            else if(geosym->getTypeId() == Part::GeomCircle::getClassTypeId()){
                Part::GeomCircle *geosymcircle = static_cast<Part::GeomCircle *>(geosym);
                Base::Vector3d cp = geosymcircle->getCenter();

                geosymcircle->setCenter(cp+2.0*(cp.Perpendicular(refGeoLine->getStartPoint(),vectline)-cp));
                isStartEndInverted.insert(std::make_pair(*it, false));
            }
            else if(geosym->getTypeId() == Part::GeomArcOfCircle::getClassTypeId()){
                Part::GeomArcOfCircle *geoaoc = static_cast<Part::GeomArcOfCircle *>(geosym);
                Base::Vector3d sp = geoaoc->getStartPoint(true);
                Base::Vector3d ep = geoaoc->getEndPoint(true);
                Base::Vector3d cp = geoaoc->getCenter();

                Base::Vector3d ssp = sp+2.0*(sp.Perpendicular(refGeoLine->getStartPoint(),vectline)-sp);
                Base::Vector3d sep = ep+2.0*(ep.Perpendicular(refGeoLine->getStartPoint(),vectline)-ep);
                Base::Vector3d scp = cp+2.0*(cp.Perpendicular(refGeoLine->getStartPoint(),vectline)-cp);

                double theta1 = Base::fmod(atan2(sep.y - scp.y, sep.x - scp.x), 2.f*M_PI);
                double theta2 = Base::fmod(atan2(ssp.y - scp.y, ssp.x - scp.x), 2.f*M_PI);

                geoaoc->setCenter(scp);
                geoaoc->setRange(theta1,theta2,true);
                isStartEndInverted.insert(std::make_pair(*it, true));
            }
            else if(geosym->getTypeId() == Part::GeomEllipse::getClassTypeId()){
                Part::GeomEllipse *geosymellipse = static_cast<Part::GeomEllipse *>(geosym);
                Base::Vector3d cp = geosymellipse->getCenter();

                Base::Vector3d majdir = geosymellipse->getMajorAxisDir();
                double majord=geosymellipse->getMajorRadius();
                double minord=geosymellipse->getMinorRadius();
                double df= sqrt(majord*majord-minord*minord);
                Base::Vector3d f1 = cp + df * majdir;

                Base::Vector3d sf1 = f1+2.0*(f1.Perpendicular(refGeoLine->getStartPoint(),vectline)-f1);
                Base::Vector3d scp = cp+2.0*(cp.Perpendicular(refGeoLine->getStartPoint(),vectline)-cp);

                geosymellipse->setMajorAxisDir(sf1-scp);

                geosymellipse->setCenter(scp);
                isStartEndInverted.insert(std::make_pair(*it, false));
            }
            else if(geosym->getTypeId() == Part::GeomArcOfEllipse::getClassTypeId()){
                Part::GeomArcOfEllipse *geosymaoe = static_cast<Part::GeomArcOfEllipse *>(geosym);
                Base::Vector3d cp = geosymaoe->getCenter();

                Base::Vector3d majdir = geosymaoe->getMajorAxisDir();
                double majord=geosymaoe->getMajorRadius();
                double minord=geosymaoe->getMinorRadius();
                double df= sqrt(majord*majord-minord*minord);
                Base::Vector3d f1 = cp + df * majdir;

                Base::Vector3d sf1 = f1+2.0*(f1.Perpendicular(refGeoLine->getStartPoint(),vectline)-f1);
                Base::Vector3d scp = cp+2.0*(cp.Perpendicular(refGeoLine->getStartPoint(),vectline)-cp);

                geosymaoe->setMajorAxisDir(sf1-scp);

                geosymaoe->setCenter(scp);

                double theta1,theta2;
                geosymaoe->getRange(theta1,theta2,true);
                theta1 = 2.0*M_PI - theta1;
                theta2 = 2.0*M_PI - theta2;
                std::swap(theta1, theta2);
                if (theta1 < 0) {
                    theta1 += 2.0*M_PI;
                    theta2 += 2.0*M_PI;
                }

                geosymaoe->setRange(theta1,theta2,true);
                isStartEndInverted.insert(std::make_pair(*it, true));
            }
            else if(geosym->getTypeId() == Part::GeomArcOfHyperbola::getClassTypeId()){
                Part::GeomArcOfHyperbola *geosymaoe = static_cast<Part::GeomArcOfHyperbola *>(geosym);
                Base::Vector3d cp = geosymaoe->getCenter();

                Base::Vector3d majdir = geosymaoe->getMajorAxisDir();
                double majord=geosymaoe->getMajorRadius();
                double minord=geosymaoe->getMinorRadius();
                double df= sqrt(majord*majord+minord*minord);
                Base::Vector3d f1 = cp + df * majdir;

                Base::Vector3d sf1 = f1+2.0*(f1.Perpendicular(refGeoLine->getStartPoint(),vectline)-f1);
                Base::Vector3d scp = cp+2.0*(cp.Perpendicular(refGeoLine->getStartPoint(),vectline)-cp);

                geosymaoe->setMajorAxisDir(sf1-scp);

                geosymaoe->setCenter(scp);

                double theta1,theta2;
                geosymaoe->getRange(theta1,theta2,true);
                theta1 = -theta1;
                theta2 = -theta2;
                std::swap(theta1, theta2);

                geosymaoe->setRange(theta1,theta2,true);
                isStartEndInverted.insert(std::make_pair(*it, true));
            }
            else if(geosym->getTypeId() == Part::GeomArcOfParabola::getClassTypeId()){
                Part::GeomArcOfParabola *geosymaoe = static_cast<Part::GeomArcOfParabola *>(geosym);
                Base::Vector3d cp = geosymaoe->getCenter();

                //double df= geosymaoe->getFocal();
                Base::Vector3d f1 = geosymaoe->getFocus();

                Base::Vector3d sf1 = f1+2.0*(f1.Perpendicular(refGeoLine->getStartPoint(),vectline)-f1);
                Base::Vector3d scp = cp+2.0*(cp.Perpendicular(refGeoLine->getStartPoint(),vectline)-cp);

                geosymaoe->setXAxisDir(sf1-scp);
                geosymaoe->setCenter(scp);

                double theta1,theta2;
                geosymaoe->getRange(theta1,theta2,true);
                theta1 = -theta1;
                theta2 = -theta2;
                std::swap(theta1, theta2);

                geosymaoe->setRange(theta1,theta2,true);
                isStartEndInverted.insert(std::make_pair(*it, true));
            }
            else if(geosym->getTypeId() == Part::GeomBSplineCurve::getClassTypeId()){
                Part::GeomBSplineCurve *geosymbsp = static_cast<Part::GeomBSplineCurve *>(geosym);

                std::vector<Base::Vector3d> poles = geosymbsp->getPoles();

                for(std::vector<Base::Vector3d>::iterator jt = poles.begin(); jt != poles.end(); ++jt){

                    (*jt) = (*jt) + 2.0*((*jt).Perpendicular(refGeoLine->getStartPoint(),vectline)-(*jt));
                }

                geosymbsp->setPoles(poles);

                isStartEndInverted.insert(std::make_pair(*it, false));
            }
            else if(geosym->getTypeId() == Part::GeomPoint::getClassTypeId()){
                Part::GeomPoint *geosympoint = static_cast<Part::GeomPoint *>(geosym);
                Base::Vector3d cp = geosympoint->getPoint();

                geosympoint->setPoint(cp+2.0*(cp.Perpendicular(refGeoLine->getStartPoint(),vectline)-cp));
                isStartEndInverted.insert(std::make_pair(*it, false));
            }
            else {
                Base::Console().Error("Unsupported Geometry!! Just copying it.\n");
                isStartEndInverted.insert(std::make_pair(*it, false));
            }

            newgeoVals.push_back(geosym);
            geoIdMap.insert(std::make_pair(*it, cgeoid));
            cgeoid++;
        }
    }
    else { //reference is a point
        refIsAxisAligned = true;
        Vector3d refpoint;
        const Part::Geometry *georef = getGeometry(refGeoId);

        if (georef->getTypeId() == Part::GeomPoint::getClassTypeId()) {
            refpoint = static_cast<const Part::GeomPoint *>(georef)->getPoint();
        }
        else if ( refGeoId == -1 && refPosId == Sketcher::PointPos::start) {
            refpoint = Vector3d(0,0,0);
        }
        else {
            switch(refPosId){
                case Sketcher::PointPos::start:
                    if(georef->getTypeId() == Part::GeomLineSegment::getClassTypeId()){
                        const Part::GeomLineSegment *geosymline = static_cast<const Part::GeomLineSegment *>(georef);
                        refpoint = geosymline->getStartPoint();
                    }
                    else if(georef->getTypeId() == Part::GeomArcOfCircle::getClassTypeId()){
                        const Part::GeomArcOfCircle *geoaoc = static_cast<const Part::GeomArcOfCircle *>(georef);
                        refpoint = geoaoc->getStartPoint(true);
                    }
                    else if(georef->getTypeId() == Part::GeomArcOfEllipse::getClassTypeId()){
                        const Part::GeomArcOfEllipse *geosymaoe = static_cast<const Part::GeomArcOfEllipse *>(georef);
                        refpoint = geosymaoe->getStartPoint(true);
                    }
                    else if(georef->getTypeId() == Part::GeomArcOfHyperbola::getClassTypeId()){
                        const Part::GeomArcOfHyperbola *geosymaoe = static_cast<const Part::GeomArcOfHyperbola *>(georef);
                        refpoint = geosymaoe->getStartPoint(true);
                    }
                    else if(georef->getTypeId() == Part::GeomArcOfParabola::getClassTypeId()){
                        const Part::GeomArcOfParabola *geosymaoe = static_cast<const Part::GeomArcOfParabola *>(georef);
                        refpoint = geosymaoe->getStartPoint(true);
                    } else if(georef->getTypeId() == Part::GeomBSplineCurve::getClassTypeId()){
                        const Part::GeomBSplineCurve *geosymbsp = static_cast<const Part::GeomBSplineCurve *>(georef);
                        refpoint = geosymbsp->getStartPoint();
                    }
                    break;
                case Sketcher::PointPos::end:
                    if(georef->getTypeId() == Part::GeomLineSegment::getClassTypeId()){
                        const Part::GeomLineSegment *geosymline = static_cast<const Part::GeomLineSegment *>(georef);
                        refpoint = geosymline->getEndPoint();
                    }
                    else if(georef->getTypeId() == Part::GeomArcOfCircle::getClassTypeId()){
                        const Part::GeomArcOfCircle *geoaoc = static_cast<const Part::GeomArcOfCircle *>(georef);
                        refpoint = geoaoc->getEndPoint(true);
                    }
                    else if(georef->getTypeId() == Part::GeomArcOfEllipse::getClassTypeId()){
                        const Part::GeomArcOfEllipse *geosymaoe = static_cast<const Part::GeomArcOfEllipse *>(georef);
                        refpoint = geosymaoe->getEndPoint(true);
                    }
                    else if(georef->getTypeId() == Part::GeomArcOfHyperbola::getClassTypeId()){
                        const Part::GeomArcOfHyperbola *geosymaoe = static_cast<const Part::GeomArcOfHyperbola *>(georef);
                        refpoint = geosymaoe->getEndPoint(true);
                    }
                    else if(georef->getTypeId() == Part::GeomArcOfParabola::getClassTypeId()){
                        const Part::GeomArcOfParabola *geosymaoe = static_cast<const Part::GeomArcOfParabola *>(georef);
                        refpoint = geosymaoe->getEndPoint(true);
                    }
                    else if(georef->getTypeId() == Part::GeomBSplineCurve::getClassTypeId()){
                        const Part::GeomBSplineCurve *geosymbsp = static_cast<const Part::GeomBSplineCurve *>(georef);
                        refpoint = geosymbsp->getEndPoint();
                    }
                    break;
                case Sketcher::PointPos::mid:
                    if(georef->getTypeId() == Part::GeomCircle::getClassTypeId()){
                        const Part::GeomCircle *geosymcircle = static_cast<const Part::GeomCircle *>(georef);
                        refpoint = geosymcircle->getCenter();
                    }
                    else if(georef->getTypeId() == Part::GeomArcOfCircle::getClassTypeId()){
                        const Part::GeomArcOfCircle *geoaoc = static_cast<const Part::GeomArcOfCircle *>(georef);
                        refpoint = geoaoc->getCenter();
                    }
                    else if(georef->getTypeId() == Part::GeomEllipse::getClassTypeId()){
                        const Part::GeomEllipse *geosymellipse = static_cast<const Part::GeomEllipse *>(georef);
                        refpoint = geosymellipse->getCenter();
                    }
                    else if(georef->getTypeId() == Part::GeomArcOfEllipse::getClassTypeId()){
                        const Part::GeomArcOfEllipse *geosymaoe = static_cast<const Part::GeomArcOfEllipse *>(georef);
                        refpoint = geosymaoe->getCenter();
                    }
                    else if(georef->getTypeId() == Part::GeomArcOfHyperbola::getClassTypeId()){
                        const Part::GeomArcOfHyperbola *geosymaoe = static_cast<const Part::GeomArcOfHyperbola *>(georef);
                        refpoint = geosymaoe->getCenter();
                    }
                    else if(georef->getTypeId() == Part::GeomArcOfParabola::getClassTypeId()){
                        const Part::GeomArcOfParabola *geosymaoe = static_cast<const Part::GeomArcOfParabola *>(georef);
                        refpoint = geosymaoe->getCenter();
                    }
                    break;
                default:
                    Base::Console().Error("Wrong PointPosId.\n");
                    return -1;
            }
        }

        for (std::vector<int>::const_iterator it = geoIdList.begin(); it != geoIdList.end(); ++it) {
            const Part::Geometry *geo = getGeometry(*it);

            Part::Geometry *geosym;

            auto gf = GeometryFacade::getFacade(geo);

            if(gf->isInternalAligned()) {
                // only add this geometry if the corresponding geometry it defines is also in the list.
                int definedGeo = GeoEnum::GeoUndef;

                for( auto c : Constraints.getValues()) {
                    if(c->Type == Sketcher::InternalAlignment && c->First == *it) {
                        definedGeo = c->Second;
                        break;
                    }
                }

                if(std::find(geoIdList.begin(), geoIdList.end(), definedGeo) != geoIdList.end() )
                    geosym = geo->copy();
                else
                    continue; // we should not mirror internal alignment geometry, unless the element they define is also mirrored

            }
            else {
                geosym = geo->copy();
            }

            // Handle Geometry
            if(geosym->getTypeId() == Part::GeomLineSegment::getClassTypeId()){
                Part::GeomLineSegment *geosymline = static_cast<Part::GeomLineSegment *>(geosym);
                Base::Vector3d sp = geosymline->getStartPoint();
                Base::Vector3d ep = geosymline->getEndPoint();
                Base::Vector3d ssp = sp + 2.0*(refpoint-sp);
                Base::Vector3d sep = ep + 2.0*(refpoint-ep);

                geosymline->setPoints(ssp, sep);
                isStartEndInverted.insert(std::make_pair(*it, false));
            }
            else if(geosym->getTypeId() == Part::GeomCircle::getClassTypeId()){
                Part::GeomCircle *geosymcircle = static_cast<Part::GeomCircle *>(geosym);
                Base::Vector3d cp = geosymcircle->getCenter();

                geosymcircle->setCenter(cp + 2.0*(refpoint-cp));
                isStartEndInverted.insert(std::make_pair(*it, false));
            }
            else if(geosym->getTypeId() == Part::GeomArcOfCircle::getClassTypeId()){
                Part::GeomArcOfCircle *geoaoc = static_cast<Part::GeomArcOfCircle *>(geosym);
                Base::Vector3d sp = geoaoc->getStartPoint(true);
                Base::Vector3d ep = geoaoc->getEndPoint(true);
                Base::Vector3d cp = geoaoc->getCenter();

                Base::Vector3d ssp = sp + 2.0*(refpoint-sp);
                Base::Vector3d sep = ep + 2.0*(refpoint-ep);
                Base::Vector3d scp = cp + 2.0*(refpoint-cp);

                double theta1 = Base::fmod(atan2(ssp.y - scp.y, ssp.x - scp.x), 2.f*M_PI);
                double theta2 = Base::fmod(atan2(sep.y - scp.y, sep.x - scp.x), 2.f*M_PI);

                geoaoc->setCenter(scp);
                geoaoc->setRange(theta1,theta2,true);
                isStartEndInverted.insert(std::make_pair(*it, false));
            }
            else if(geosym->getTypeId() == Part::GeomEllipse::getClassTypeId()){
                Part::GeomEllipse *geosymellipse = static_cast<Part::GeomEllipse *>(geosym);
                Base::Vector3d cp = geosymellipse->getCenter();

                Base::Vector3d majdir = geosymellipse->getMajorAxisDir();
                double majord=geosymellipse->getMajorRadius();
                double minord=geosymellipse->getMinorRadius();
                double df= sqrt(majord*majord-minord*minord);
                Base::Vector3d f1 = cp + df * majdir;

                Base::Vector3d sf1 = f1 + 2.0*(refpoint-f1);
                Base::Vector3d scp = cp + 2.0*(refpoint-cp);

                geosymellipse->setMajorAxisDir(sf1-scp);

                geosymellipse->setCenter(scp);
                isStartEndInverted.insert(std::make_pair(*it, false));
            }
            else if(geosym->getTypeId() == Part::GeomArcOfEllipse::getClassTypeId()){
                Part::GeomArcOfEllipse *geosymaoe = static_cast<Part::GeomArcOfEllipse *>(geosym);
                Base::Vector3d cp = geosymaoe->getCenter();

                Base::Vector3d majdir = geosymaoe->getMajorAxisDir();
                double majord=geosymaoe->getMajorRadius();
                double minord=geosymaoe->getMinorRadius();
                double df= sqrt(majord*majord-minord*minord);
                Base::Vector3d f1 = cp + df * majdir;

                Base::Vector3d sf1 = f1 + 2.0*(refpoint-f1);
                Base::Vector3d scp = cp + 2.0*(refpoint-cp);

                geosymaoe->setMajorAxisDir(sf1-scp);

                geosymaoe->setCenter(scp);
                isStartEndInverted.insert(std::make_pair(*it, false));
            }
            else if(geosym->getTypeId() == Part::GeomArcOfHyperbola::getClassTypeId()){
                Part::GeomArcOfHyperbola *geosymaoe = static_cast<Part::GeomArcOfHyperbola *>(geosym);
                Base::Vector3d cp = geosymaoe->getCenter();

                Base::Vector3d majdir = geosymaoe->getMajorAxisDir();
                double majord=geosymaoe->getMajorRadius();
                double minord=geosymaoe->getMinorRadius();
                double df= sqrt(majord*majord+minord*minord);
                Base::Vector3d f1 = cp + df * majdir;

                Base::Vector3d sf1 = f1 + 2.0*(refpoint-f1);
                Base::Vector3d scp = cp + 2.0*(refpoint-cp);

                geosymaoe->setMajorAxisDir(sf1-scp);

                geosymaoe->setCenter(scp);
                isStartEndInverted.insert(std::make_pair(*it, false));
            }
            else if(geosym->getTypeId() == Part::GeomArcOfParabola::getClassTypeId()){
                Part::GeomArcOfParabola *geosymaoe = static_cast<Part::GeomArcOfParabola *>(geosym);
                Base::Vector3d cp = geosymaoe->getCenter();

                /*double df= geosymaoe->getFocal();*/
                Base::Vector3d f1 = geosymaoe->getFocus();

                Base::Vector3d sf1 = f1 + 2.0*(refpoint-f1);
                Base::Vector3d scp = cp + 2.0*(refpoint-cp);

                geosymaoe->setXAxisDir(sf1-scp);
                geosymaoe->setCenter(scp);

                isStartEndInverted.insert(std::make_pair(*it, false));
            }
            else if(geosym->getTypeId() == Part::GeomBSplineCurve::getClassTypeId()){
                Part::GeomBSplineCurve *geosymbsp = static_cast<Part::GeomBSplineCurve *>(geosym);

                std::vector<Base::Vector3d> poles = geosymbsp->getPoles();

                for(std::vector<Base::Vector3d>::iterator it = poles.begin(); it != poles.end(); ++it){
                    (*it) = (*it) + 2.0*(refpoint-(*it));
                }

                geosymbsp->setPoles(poles);

                //isStartEndInverted.insert(std::make_pair(*it, false));
            }
            else if(geosym->getTypeId() == Part::GeomPoint::getClassTypeId()){
                Part::GeomPoint *geosympoint = static_cast<Part::GeomPoint *>(geosym);
                Base::Vector3d cp = geosympoint->getPoint();

                geosympoint->setPoint(cp + 2.0*(refpoint-cp));
                isStartEndInverted.insert(std::make_pair(*it, false));
            }
            else {
                Base::Console().Error("Unsupported Geometry!! Just copying it.\n");
                isStartEndInverted.insert(std::make_pair(*it, false));
            }

            newgeoVals.push_back(geosym);
            geoIdMap.insert(std::make_pair(*it, cgeoid));
            cgeoid++;
        }
    }

    // add the geometry

    // Block acceptGeometry in OnChanged to avoid unnecessary checks and updates
    {
        Base::StateLocker lock(internaltransaction, true);
        Geometry.setValues(std::move(newgeoVals));

        for (std::vector<Constraint *>::const_iterator it = constrvals.begin(); it != constrvals.end(); ++it) {

            auto fit = geoIdMap.find((*it)->First); // we look in the map, because we might have skipped internal alignment geometry

            if(fit != geoIdMap.end()) { // if First of constraint is in geoIdList

                if( (*it)->Second == GeoEnum::GeoUndef /*&& (*it)->Third == GeoEnum::GeoUndef*/) {
                    if (refIsAxisAligned) {
                        // in this case we want to keep the Vertical, Horizontal constraints
                        // DistanceX ,and DistanceY constraints should also be possible to keep in this case,
                        // but keeping them causes segfault, not sure why.

                        if( (*it)->Type != Sketcher::DistanceX && (*it)->Type != Sketcher::DistanceY ) {
                            Constraint *constNew = (*it)->copy();
                            constNew->First = fit->second;
                            newconstrVals.push_back(constNew);
                        }

                    } else if( (*it)->Type != Sketcher::DistanceX &&
                               (*it)->Type != Sketcher::DistanceY &&
                               (*it)->Type != Sketcher::Vertical &&
                               (*it)->Type != Sketcher::Horizontal ) { // this includes all non-directional single GeoId constraints, as radius, diameter, weight,...

                            Constraint *constNew = (*it)->copy();
                            constNew->First = fit->second;
                            newconstrVals.push_back(constNew);
                    }

                }
                else { // other geoids intervene in this constraint

                    auto sit = geoIdMap.find((*it)->Second);

                    if(sit != geoIdMap.end()) { // Second is also in the list

                        if( (*it)->Third == GeoEnum::GeoUndef ) {
                            if((*it)->Type ==  Sketcher::Coincident     ||
                            (*it)->Type ==  Sketcher::Perpendicular     ||
                            (*it)->Type ==  Sketcher::Parallel          ||
                            (*it)->Type ==  Sketcher::Tangent           ||
                            (*it)->Type ==  Sketcher::Distance          ||
                            (*it)->Type ==  Sketcher::Equal             ||
                            (*it)->Type ==  Sketcher::Angle             ||
                            (*it)->Type ==  Sketcher::PointOnObject     ||
                            (*it)->Type ==  Sketcher::InternalAlignment ){
                                Constraint *constNew = (*it)->copy();

                                constNew->First = fit->second;
                                constNew->Second = sit->second;
                                if(isStartEndInverted[(*it)->First]){
                                    if((*it)->FirstPos == Sketcher::PointPos::start)
                                        constNew->FirstPos = Sketcher::PointPos::end;
                                    else if((*it)->FirstPos == Sketcher::PointPos::end)
                                        constNew->FirstPos = Sketcher::PointPos::start;
                                }
                                if(isStartEndInverted[(*it)->Second]){
                                    if((*it)->SecondPos == Sketcher::PointPos::start)
                                        constNew->SecondPos = Sketcher::PointPos::end;
                                    else if((*it)->SecondPos == Sketcher::PointPos::end)
                                        constNew->SecondPos = Sketcher::PointPos::start;
                                }

                                if (constNew->Type == Tangent || constNew->Type == Perpendicular)
                                    AutoLockTangencyAndPerpty(constNew,true);

                                if( ((*it)->Type ==  Sketcher::Angle) && (refPosId == Sketcher::PointPos::none)) {
                                    constNew->setValue(-(*it)->getValue());
                                }

                                newconstrVals.push_back(constNew);
                            }
                        }
                        else { // three GeoIds intervene in constraint
                            auto tit = geoIdMap.find((*it)->Third);

                            if(tit != geoIdMap.end()) { // Third is also in the list
                                Constraint *constNew = (*it)->copy();
                                constNew->First = fit->second;
                                constNew->Second = sit->second;
                                constNew->Third = tit->second;
                                if(isStartEndInverted[(*it)->First]){
                                    if((*it)->FirstPos == Sketcher::PointPos::start)
                                        constNew->FirstPos = Sketcher::PointPos::end;
                                    else if((*it)->FirstPos == Sketcher::PointPos::end)
                                        constNew->FirstPos = Sketcher::PointPos::start;
                                }
                                if(isStartEndInverted[(*it)->Second]){
                                    if((*it)->SecondPos == Sketcher::PointPos::start)
                                        constNew->SecondPos = Sketcher::PointPos::end;
                                    else if((*it)->SecondPos == Sketcher::PointPos::end)
                                        constNew->SecondPos = Sketcher::PointPos::start;
                                }
                                if(isStartEndInverted[(*it)->Third]){
                                    if((*it)->ThirdPos == Sketcher::PointPos::start)
                                        constNew->ThirdPos = Sketcher::PointPos::end;
                                    else if((*it)->ThirdPos == Sketcher::PointPos::end)
                                        constNew->ThirdPos = Sketcher::PointPos::start;
                                }
                                newconstrVals.push_back(constNew);
                            }
                        }
                    }
                }
            }
        }

    if( newconstrVals.size() > constrvals.size() )
        Constraints.setValues(std::move(newconstrVals));

    }

    // we delayed update, so trigger it now.
    // Update geometry indices and rebuild vertexindex now via onChanged, so that ViewProvider::UpdateData is triggered.
    Geometry.touch();

    return Geometry.getSize()-1;
}

int SketchObject::addCopy(const std::vector<int> &geoIdList, const Base::Vector3d& displacement, bool moveonly /*=false*/,
                          bool clone /*=false*/, int csize/*=2*/, int rsize/*=1*/, bool constraindisplacement /*= false*/,
                          double perpscale /*= 1.0*/)
{
    Base::StateLocker lock(managedoperation, true); // no need to check input data validity as this is an sketchobject managed operation.

    const std::vector< Part::Geometry * > &geovals = getInternalGeometry();
    std::vector< Part::Geometry * > newgeoVals(geovals);

    const std::vector< Constraint * > &constrvals = this->Constraints.getValues();
    std::vector< Constraint * > newconstrVals(constrvals);

    if(!moveonly) {
        newgeoVals.reserve(geovals.size()+geoIdList.size());
    }

    std::vector<int> newgeoIdList(geoIdList);

    if(newgeoIdList.empty()) {// default option to operate on all the geometry
        for(int i = 0; i < int(geovals.size()); i++)
            newgeoIdList.push_back(i);
    }

    int cgeoid = getHighestCurveIndex()+1;

    int iterfirstgeoid = -1 ;

    Base::Vector3d iterfirstpoint;

    int refgeoid = -1;

    int colrefgeoid = 0, rowrefgeoid = 0;

    int currentrowfirstgeoid= -1, prevrowstartfirstgeoid = -1, prevfirstgeoid = -1;

    Sketcher::PointPos refposId = Sketcher::PointPos::none;

    std::map<int, int> geoIdMap;

    Base::Vector3d perpendicularDisplacement = Base::Vector3d(perpscale*displacement.y,perpscale*-displacement.x,0);

    int x,y;

    for (y=0;y<rsize;y++) {
        for (x=0;x<csize;x++) {

            if(x == 0 && y == 0) { // the reference for constraining array elements is the first valid point of the first element
                const Part::Geometry *geo = getGeometry(*(newgeoIdList.begin()));

                auto gf = GeometryFacade::getFacade(geo);

                if(gf->isInternalAligned() && !moveonly) {
                    // only add this geometry if the corresponding geometry it defines is also in the list.
                    int definedGeo = GeoEnum::GeoUndef;

                    for( auto c : Constraints.getValues()) {
                        if(c->Type == Sketcher::InternalAlignment && c->First == *(newgeoIdList.begin())) {
                            definedGeo = c->Second;
                            break;
                        }
                    }

                    if(std::find(newgeoIdList.begin(), newgeoIdList.end(), definedGeo) == newgeoIdList.end() ) {
                        // the first element setting the reference is an internal alignment geometry, wherein the geometry
                        // it defines is not part of the copy operation.
                        THROWM(Base::ValueError,"A move/copy/array operation on an internal alignment geometry is only possible together with the geometry it defines.")
                    }
                }

                refgeoid=*(newgeoIdList.begin());
                currentrowfirstgeoid = refgeoid;
                iterfirstgeoid = refgeoid;
                if(geo->getTypeId() == Part::GeomCircle::getClassTypeId() ||
                    geo->getTypeId() == Part::GeomEllipse::getClassTypeId() ){
                    refposId = Sketcher::PointPos::mid;
                }
                else
                    refposId = Sketcher::PointPos::start;

                continue; // the first element is already in place
            }
            else {
                prevfirstgeoid = iterfirstgeoid;

                iterfirstgeoid = cgeoid;

                if( x == 0 ) { // if first element of second row
                    prevrowstartfirstgeoid = currentrowfirstgeoid;
                    currentrowfirstgeoid = cgeoid;
                }
            }

            int index = 0;
            for (std::vector<int>::const_iterator it = newgeoIdList.begin(); it != newgeoIdList.end(); ++it, index++) {
                const Part::Geometry *geo = getGeometry(*it);

                Part::Geometry *geocopy;

                auto gf = GeometryFacade::getFacade(geo);

                if(gf->isInternalAligned() && !moveonly) {
                    // only add this geometry if the corresponding geometry it defines is also in the list.
                    int definedGeo = GeoEnum::GeoUndef;

                    for( auto c : Constraints.getValues()) {
                        if(c->Type == Sketcher::InternalAlignment && c->First == *it) {
                            definedGeo = c->Second;
                            break;
                        }
                    }

                    if(std::find(newgeoIdList.begin(), newgeoIdList.end(), definedGeo) == newgeoIdList.end() )
                        continue; // we should not copy internal alignment geometry, unless the element they define is also mirrored

                }

                // We have already cloned all geometry and constraints, we only need a copy if not moving
                if(!moveonly)
                    geocopy = geo->copy();
                else
                    geocopy = newgeoVals[*it];

                // Handle Geometry
                if(geocopy->getTypeId() == Part::GeomLineSegment::getClassTypeId()){
                    Part::GeomLineSegment *geosymline = static_cast<Part::GeomLineSegment *>(geocopy);
                    Base::Vector3d ep = geosymline->getEndPoint();
                    Base::Vector3d ssp = geosymline->getStartPoint()+double(x)*displacement+double(y)*perpendicularDisplacement;

                    geosymline->setPoints(  ssp,
                                            ep+double(x)*displacement+double(y)*perpendicularDisplacement);

                    if(it == newgeoIdList.begin())
                        iterfirstpoint = ssp;
                }
                else if(geocopy->getTypeId() == Part::GeomCircle::getClassTypeId()){
                    Part::GeomCircle *geosymcircle = static_cast<Part::GeomCircle *>(geocopy);
                    Base::Vector3d cp = geosymcircle->getCenter();
                    Base::Vector3d scp = cp+double(x)*displacement+double(y)*perpendicularDisplacement;

                    geosymcircle->setCenter(scp);

                    if(it == newgeoIdList.begin())
                        iterfirstpoint = scp;
                }
                else if(geocopy->getTypeId() == Part::GeomArcOfCircle::getClassTypeId()){
                    Part::GeomArcOfCircle *geoaoc = static_cast<Part::GeomArcOfCircle *>(geocopy);
                    Base::Vector3d cp = geoaoc->getCenter();
                    Base::Vector3d scp = cp+double(x)*displacement+double(y)*perpendicularDisplacement;

                    geoaoc->setCenter(scp);

                    if(it == newgeoIdList.begin())
                        iterfirstpoint = geoaoc->getStartPoint(true);
                }
                else if(geocopy->getTypeId() == Part::GeomEllipse::getClassTypeId()){
                    Part::GeomEllipse *geosymellipse = static_cast<Part::GeomEllipse *>(geocopy);
                    Base::Vector3d cp = geosymellipse->getCenter();
                    Base::Vector3d scp = cp+double(x)*displacement+double(y)*perpendicularDisplacement;

                    geosymellipse->setCenter(scp);

                    if(it == newgeoIdList.begin())
                        iterfirstpoint = scp;
                }
                else if(geocopy->getTypeId() == Part::GeomArcOfEllipse::getClassTypeId()){
                    Part::GeomArcOfEllipse *geoaoe = static_cast<Part::GeomArcOfEllipse *>(geocopy);
                    Base::Vector3d cp = geoaoe->getCenter();
                    Base::Vector3d scp = cp+double(x)*displacement+double(y)*perpendicularDisplacement;

                    geoaoe->setCenter(scp);

                    if(it == newgeoIdList.begin())
                        iterfirstpoint = geoaoe->getStartPoint(true);
                }
                else if(geocopy->getTypeId() == Part::GeomArcOfHyperbola::getClassTypeId()){
                    Part::GeomArcOfHyperbola *geoaoe = static_cast<Part::GeomArcOfHyperbola *>(geocopy);
                    Base::Vector3d cp = geoaoe->getCenter();
                    Base::Vector3d scp = cp+double(x)*displacement+double(y)*perpendicularDisplacement;

                    geoaoe->setCenter(scp);

                    if(it == newgeoIdList.begin())
                        iterfirstpoint = geoaoe->getStartPoint(true);
                }
                else if(geocopy->getTypeId() == Part::GeomArcOfParabola::getClassTypeId()){
                    Part::GeomArcOfParabola *geoaoe = static_cast<Part::GeomArcOfParabola *>(geocopy);
                    Base::Vector3d cp = geoaoe->getCenter();
                    Base::Vector3d scp = cp+double(x)*displacement+double(y)*perpendicularDisplacement;

                    geoaoe->setCenter(scp);

                    if(it == newgeoIdList.begin())
                        iterfirstpoint = geoaoe->getStartPoint(true);
                }
                else if(geocopy->getTypeId() == Part::GeomBSplineCurve::getClassTypeId()){
                    Part::GeomBSplineCurve *geobsp = static_cast<Part::GeomBSplineCurve *>(geocopy);

                    std::vector<Base::Vector3d> poles = geobsp->getPoles();

                    for(std::vector<Base::Vector3d>::iterator jt = poles.begin(); jt != poles.end(); ++jt){

                        (*jt) = (*jt) + double(x)*displacement + double(y)*perpendicularDisplacement;
                    }

                    geobsp->setPoles(poles);

                    if (it == newgeoIdList.begin())
                        iterfirstpoint = geobsp->getStartPoint();
                }
                else if(geocopy->getTypeId() == Part::GeomPoint::getClassTypeId()){
                    Part::GeomPoint *geopoint = static_cast<Part::GeomPoint *>(geocopy);
                    Base::Vector3d cp = geopoint->getPoint();
                    Base::Vector3d scp = cp+double(x)*displacement+double(y)*perpendicularDisplacement;
                    geopoint->setPoint(scp);

                    if(it == newgeoIdList.begin())
                        iterfirstpoint = scp;
                }
                else {
                    Base::Console().Error("Unsupported Geometry!! Just skipping it.\n");
                    continue;
                }

                if(!moveonly) { // we are copying
                    newgeoVals.push_back(geocopy);
                    geoIdMap.insert(std::make_pair(*it, cgeoid));
                    cgeoid++;
                }
            }

            if(!moveonly) {
                // handle geometry constraints
                for (std::vector<Constraint *>::const_iterator it = constrvals.begin(); it != constrvals.end(); ++it) {

                    auto fit = geoIdMap.find((*it)->First);

                    if(fit != geoIdMap.end()) { // if First of constraint is in geoIdList

                        if( (*it)->Second == GeoEnum::GeoUndef /*&& (*it)->Third == GeoEnum::GeoUndef*/) {
                            if( ((*it)->Type != Sketcher::DistanceX && (*it)->Type != Sketcher::DistanceY ) ||
                                (*it)->FirstPos == Sketcher::PointPos::none ) { // if it is not a point locking DistanceX/Y
                                    if (((*it)->Type == Sketcher::DistanceX ||
                                        (*it)->Type == Sketcher::DistanceY  ||
                                        (*it)->Type == Sketcher::Distance   ||
                                        (*it)->Type == Sketcher::Diameter   ||
                                        (*it)->Type == Sketcher::Weight     ||
                                        (*it)->Type == Sketcher::Radius ) && clone ) {
                                        // Distances on a single Element are mapped to equality constraints in clone mode
                                        Constraint *constNew = (*it)->copy();
                                        constNew->Type = Sketcher::Equal;
                                        constNew->isDriving = true;
                                        constNew->Second = fit->second; // first is already (*it->First)
                                        newconstrVals.push_back(constNew);
                                    }
                                    else if ((*it)->Type == Sketcher::Angle && clone) {
                                        if (getGeometry((*it)->First)->getTypeId() == Part::GeomLineSegment::getClassTypeId()) {
                                            // Angles on a single Element are mapped to parallel constraints in clone mode
                                            Constraint *constNew = (*it)->copy();
                                            constNew->Type = Sketcher::Parallel;
                                            constNew->isDriving = true;
                                            constNew->Second = fit->second; // first is already (*it->First)
                                            newconstrVals.push_back(constNew);
                                        }
                                    }
                                    else {
                                        Constraint *constNew = (*it)->copy();
                                        constNew->First = fit->second;
                                        newconstrVals.push_back(constNew);
                                    }
                            }
                        }
                        else { // other geoids intervene in this constraint

                            auto sit = geoIdMap.find((*it)->Second);

                            if(sit != geoIdMap.end()) { // Second is also in the list
                                if( (*it)->Third == GeoEnum::GeoUndef ) {
                                    if (((*it)->Type == Sketcher::DistanceX ||
                                        (*it)->Type == Sketcher::DistanceY ||
                                        (*it)->Type == Sketcher::Distance) && ((*it)->First == (*it)->Second) && clone ) {
                                        // Distances on a two Elements, which must be points of the same line are mapped to equality constraints in clone mode
                                        Constraint *constNew = (*it)->copy();
                                        constNew->Type = Sketcher::Equal;
                                        constNew->isDriving = true;
                                        constNew->FirstPos = Sketcher::PointPos::none;
                                        constNew->Second = fit->second; // first is already (*it->First)
                                        constNew->SecondPos = Sketcher::PointPos::none;
                                        newconstrVals.push_back(constNew);
                                    }
                                    else { // this includes InternalAlignment constraints
                                        Constraint *constNew = (*it)->copy();
                                        constNew->First = fit->second;
                                        constNew->Second = sit->second;
                                        newconstrVals.push_back(constNew);
                                    }
                                }
                                else {
                                    auto tit = geoIdMap.find((*it)->Third);

                                    if(tit != geoIdMap.end()) { // Third is also in the list
                                        Constraint *constNew = (*it)->copy();
                                        constNew->First = fit->second;
                                        constNew->Second = sit->second;
                                        constNew->Third = tit->second;

                                        newconstrVals.push_back(constNew);
                                    }
                                }
                            }
                        }
                    }
                }

                // handle inter-geometry constraints
                if(constraindisplacement){

                    // add a construction line
                    Part::GeomLineSegment *constrline= new Part::GeomLineSegment();

                    Base::Vector3d sp = getPoint(refgeoid,refposId)+ ( ( x == 0 )?
                                    (double(x)*displacement+double(y-1)*perpendicularDisplacement):
                                    (double(x-1)*displacement+double(y)*perpendicularDisplacement)); // position of the reference point
                    Base::Vector3d ep = iterfirstpoint; // position of the current instance corresponding point
                    constrline->setPoints(sp,ep);
                    GeometryFacade::setConstruction(constrline,true);

                    newgeoVals.push_back(constrline);

                    Constraint *constNew;

                    if(x == 0) { // first element of a row

                        // add coincidents for construction line
                        constNew = new Constraint();
                        constNew->Type = Sketcher::Coincident;
                        constNew->First = prevrowstartfirstgeoid;
                        constNew->FirstPos = refposId;
                        constNew->Second = cgeoid;
                        constNew->SecondPos = Sketcher::PointPos::start;
                        newconstrVals.push_back(constNew);

                        constNew = new Constraint();
                        constNew->Type = Sketcher::Coincident;
                        constNew->First = iterfirstgeoid;
                        constNew->FirstPos = refposId;
                        constNew->Second = cgeoid;
                        constNew->SecondPos = Sketcher::PointPos::end;
                        newconstrVals.push_back(constNew);

                        if( y == 1 ) { // it is the first added element of this row in the perpendicular to displacementvector direction
                            rowrefgeoid = cgeoid;
                            cgeoid++;

                            // add length (or equal if perpscale==1) and perpendicular
                            if(perpscale==1.0) {
                                constNew = new Constraint();
                                constNew->Type = Sketcher::Equal;
                                constNew->First = rowrefgeoid;
                                constNew->FirstPos = Sketcher::PointPos::none;
                                constNew->Second = colrefgeoid;
                                constNew->SecondPos = Sketcher::PointPos::none;
                                newconstrVals.push_back(constNew);
                            } else {
                                constNew = new Constraint();
                                constNew->Type = Sketcher::Distance;
                                constNew->First = rowrefgeoid;
                                constNew->FirstPos = Sketcher::PointPos::none;
                                constNew->setValue(perpendicularDisplacement.Length());
                                newconstrVals.push_back(constNew);
                            }

                            constNew = new Constraint();
                            constNew->Type = Sketcher::Perpendicular;
                            constNew->First = rowrefgeoid;
                            constNew->FirstPos = Sketcher::PointPos::none;
                            constNew->Second = colrefgeoid;
                            constNew->SecondPos = Sketcher::PointPos::none;
                            newconstrVals.push_back(constNew);
                        }
                        else { // it is just one more element in the col direction
                            cgeoid++;

                            // all other first rowers get an equality and perpendicular constraint
                            constNew = new Constraint();
                            constNew->Type = Sketcher::Equal;
                            constNew->First = rowrefgeoid;
                            constNew->FirstPos = Sketcher::PointPos::none;
                            constNew->Second = cgeoid-1;
                            constNew->SecondPos = Sketcher::PointPos::none;
                            newconstrVals.push_back(constNew);

                            constNew = new Constraint();
                            constNew->Type = Sketcher::Perpendicular;
                            constNew->First = cgeoid-1;
                            constNew->FirstPos = Sketcher::PointPos::none;
                            constNew->Second = colrefgeoid;
                            constNew->SecondPos = Sketcher::PointPos::none;
                            newconstrVals.push_back(constNew);
                        }
                    }
                    else { // any element not being the first element of a row

                        // add coincidents for construction line
                        constNew = new Constraint();
                        constNew->Type = Sketcher::Coincident;
                        constNew->First = prevfirstgeoid;
                        constNew->FirstPos = refposId;
                        constNew->Second = cgeoid;
                        constNew->SecondPos = Sketcher::PointPos::start;
                        newconstrVals.push_back(constNew);

                        constNew = new Constraint();
                        constNew->Type = Sketcher::Coincident;
                        constNew->First = iterfirstgeoid;
                        constNew->FirstPos = refposId;
                        constNew->Second = cgeoid;
                        constNew->SecondPos = Sketcher::PointPos::end;
                        newconstrVals.push_back(constNew);

                        if(y == 0 && x == 1) { // first element of the first row
                                colrefgeoid = cgeoid;
                                cgeoid++;

                                // add length and Angle
                                constNew = new Constraint();
                                constNew->Type = Sketcher::Distance;
                                constNew->First = colrefgeoid;
                                constNew->FirstPos = Sketcher::PointPos::none;
                                constNew->setValue(displacement.Length());
                                newconstrVals.push_back(constNew);

                                constNew = new Constraint();
                                constNew->Type = Sketcher::Angle;
                                constNew->First = colrefgeoid;
                                constNew->FirstPos = Sketcher::PointPos::none;
                                constNew->setValue(atan2(displacement.y,displacement.x));
                                newconstrVals.push_back(constNew);
                        }
                        else { // any other element
                            cgeoid++;

                            // all other elements get an equality and parallel constraint
                            constNew = new Constraint();
                            constNew->Type = Sketcher::Equal;
                            constNew->First = colrefgeoid;
                            constNew->FirstPos = Sketcher::PointPos::none;
                            constNew->Second = cgeoid-1;
                            constNew->SecondPos = Sketcher::PointPos::none;
                            newconstrVals.push_back(constNew);

                            constNew = new Constraint();
                            constNew->Type = Sketcher::Parallel;
                            constNew->First = cgeoid-1;
                            constNew->FirstPos = Sketcher::PointPos::none;
                            constNew->Second = colrefgeoid;
                            constNew->SecondPos = Sketcher::PointPos::none;
                            newconstrVals.push_back(constNew);
                        }
                    }
                }

                geoIdMap.clear(); // after each creation reset map so that the key-value is univoque (only for operations other than move)
            }
        }
    }

    // Block acceptGeometry in OnChanged to avoid unnecessary checks and updates
    {
        Base::StateLocker lock(internaltransaction, true);
        Geometry.setValues(std::move(newgeoVals));

        if( newconstrVals.size() > constrvals.size() )
            Constraints.setValues(std::move(newconstrVals));
    }

    // we inhibited update, so we trigger it now
    // Update geometry indices and rebuild vertexindex now via onChanged, so that ViewProvider::UpdateData is triggered.
    Geometry.touch();

    return Geometry.getSize()-1;

}


int SketchObject::removeAxesAlignment(const std::vector<int> &geoIdList)
{
    Base::StateLocker lock(managedoperation, true); // no need to check input data validity as this is an sketchobject managed operation.

    const std::vector< Constraint * > &constrvals = this->Constraints.getValues();

    unsigned int nhoriz = 0;
    unsigned int nvert = 0;

    bool changed = false;

    std::vector<std::pair<size_t, Sketcher::ConstraintType>> changeConstraintIndices;

    for (size_t i = 0; i < constrvals.size(); i++) {
        for( auto geoid : geoIdList) {
            if (constrvals[i]->First == geoid || constrvals[i]->Second == geoid || constrvals[i]->Third == geoid) {
                switch(constrvals[i]->Type) {
                    case Sketcher::Horizontal:
                         if( constrvals[i]->FirstPos == Sketcher::PointPos::none &&
                             constrvals[i]->SecondPos == Sketcher::PointPos::none ) {
                            changeConstraintIndices.emplace_back(i, constrvals[i]->Type);
                            nhoriz++;
                         }
                        break;
                    case Sketcher::Vertical:
                         if( constrvals[i]->FirstPos == Sketcher::PointPos::none &&
                             constrvals[i]->SecondPos == Sketcher::PointPos::none ) {
                            changeConstraintIndices.emplace_back(i, constrvals[i]->Type);
                            nvert++;
                         }
                        break;
                    case Sketcher::Symmetric: // only remove symmetric to axes
                        if( (constrvals[i]->Third == GeoEnum::HAxis || constrvals[i]->Third == GeoEnum::VAxis) &&
                            constrvals[i]->ThirdPos == Sketcher::PointPos::none )
                            changeConstraintIndices.emplace_back(i, constrvals[i]->Type);
                        break;
                    case Sketcher::PointOnObject:
                        if( (constrvals[i]->Second == GeoEnum::HAxis || constrvals[i]->Second == GeoEnum::VAxis) &&
                            constrvals[i]->SecondPos == Sketcher::PointPos::none )
                            changeConstraintIndices.emplace_back(i, constrvals[i]->Type);
                        break;
                    case Sketcher::DistanceX:
                    case Sketcher::DistanceY:
                        changeConstraintIndices.emplace_back(i, constrvals[i]->Type);
                        break;
                    default:
                        break;
                }
            }
        }
    }

    if(changeConstraintIndices.empty())
        return 0; // nothing to be done

    std::vector< Constraint * > newconstrVals;
    newconstrVals.reserve(constrvals.size());

    int referenceHorizontal = GeoEnum::GeoUndef;
    int referenceVertical = GeoEnum::GeoUndef;

    int cindex = 0;
    for (size_t i = 0; i < constrvals.size(); i++) {
        if ( i == changeConstraintIndices[cindex].first ) {
            if(changeConstraintIndices[cindex].second == Sketcher::Horizontal && nhoriz > 0) {
                changed = true;
                if(referenceHorizontal == GeoEnum::GeoUndef) {
                    referenceHorizontal = constrvals[i]->First;
                }
                else {

                    auto newConstr = new Constraint();

                    newConstr->Type = Sketcher::Parallel;
                    newConstr->First = referenceHorizontal;
                    newConstr->Second = constrvals[i]->First;

                    newconstrVals.push_back(newConstr);
                }
            }
            else if(changeConstraintIndices[cindex].second == Sketcher::Vertical && nvert > 0) {
                changed = true;
                if(referenceVertical == GeoEnum::GeoUndef) {
                    referenceVertical = constrvals[i]->First;;
                }
                else {
                    auto newConstr = new Constraint();

                    newConstr->Type = Sketcher::Parallel;
                    newConstr->First = referenceVertical;
                    newConstr->Second = constrvals[i]->First;

                    newconstrVals.push_back(newConstr);
                }
            }
            else if(changeConstraintIndices[cindex].second == Sketcher::Symmetric ||
                    changeConstraintIndices[cindex].second == Sketcher::PointOnObject) {
                changed = true; // We remove symmetric on axes
            }
            else if(changeConstraintIndices[cindex].second == Sketcher::DistanceX ||
                    changeConstraintIndices[cindex].second == Sketcher::DistanceY) {
                changed = true; // We remove symmetric on axes
                newconstrVals.push_back(constrvals[i]->clone());
                newconstrVals.back()->Type = Sketcher::Distance;
            }

            cindex++;
        }
        else {
            newconstrVals.push_back(constrvals[i]);
        }
    }

    if( nhoriz > 0 && nvert > 0 ) {
        auto newConstr = new Constraint();

        newConstr->Type = Sketcher::Perpendicular;
        newConstr->First = referenceVertical;
        newConstr->Second = referenceHorizontal;

        newconstrVals.push_back(newConstr);
    }

    if(changed)
        Constraints.setValues(std::move(newconstrVals));

    return 0;

}

int SketchObject::exposeInternalGeometry(int GeoId)
{
    if (GeoId < 0 || GeoId > getHighestCurveIndex())
        return -1;

    const Part::Geometry *geo = getGeometry(GeoId);
    // Only for supported types
    if(geo->getTypeId() == Part::GeomEllipse::getClassTypeId() || geo->getTypeId() == Part::GeomArcOfEllipse::getClassTypeId()) {
        // First we search what has to be restored
        bool major=false;
        bool minor=false;
        bool focus1=false;
        bool focus2=false;

        const std::vector< Sketcher::Constraint * > &vals = Constraints.getValues();

        for (std::vector< Sketcher::Constraint * >::const_iterator it= vals.begin();
                it != vals.end(); ++it) {
            if((*it)->Type == Sketcher::InternalAlignment && (*it)->Second == GeoId)
            {
                switch((*it)->AlignmentType){
                    case Sketcher::EllipseMajorDiameter:
                        major=true;
                        break;
                    case Sketcher::EllipseMinorDiameter:
                        minor=true;
                        break;
                    case Sketcher::EllipseFocus1:
                        focus1=true;
                        break;
                    case Sketcher::EllipseFocus2:
                        focus2=true;
                        break;
                    default:
                        return -1;
                }
            }
        }

        int currentgeoid= getHighestCurveIndex();
        int incrgeo= 0;

        Base::Vector3d center;
        double majord;
        double minord;
        Base::Vector3d majdir;

        std::vector<Part::Geometry *> igeo;
        std::vector<Constraint *> icon;

        if(geo->getTypeId() == Part::GeomEllipse::getClassTypeId()){
            const Part::GeomEllipse *ellipse = static_cast<const Part::GeomEllipse *>(geo);

            center=ellipse->getCenter();
            majord=ellipse->getMajorRadius();
            minord=ellipse->getMinorRadius();
            majdir=ellipse->getMajorAxisDir();
        }
        else {
            const Part::GeomArcOfEllipse *aoe = static_cast<const Part::GeomArcOfEllipse *>(geo);

            center=aoe->getCenter();
            majord=aoe->getMajorRadius();
            minord=aoe->getMinorRadius();
            majdir=aoe->getMajorAxisDir();
        }

        Base::Vector3d mindir = Vector3d(-majdir.y, majdir.x);

        Base::Vector3d majorpositiveend = center + majord * majdir;
        Base::Vector3d majornegativeend = center - majord * majdir;
        Base::Vector3d minorpositiveend = center + minord * mindir;
        Base::Vector3d minornegativeend = center - minord * mindir;

        double df= sqrt(majord*majord-minord*minord);

        Base::Vector3d focus1P = center + df * majdir;
        Base::Vector3d focus2P = center - df * majdir;

        if(!major)
        {
            Part::GeomLineSegment *lmajor = new Part::GeomLineSegment();
            lmajor->setPoints(majorpositiveend,majornegativeend);

            igeo.push_back(lmajor);

            Sketcher::Constraint *newConstr = new Sketcher::Constraint();
            newConstr->Type = Sketcher::InternalAlignment;
            newConstr->AlignmentType = EllipseMajorDiameter;
            newConstr->First = currentgeoid+incrgeo+1;
            newConstr->Second = GeoId;

            icon.push_back(newConstr);
            incrgeo++;
        }
        if(!minor)
        {
            Part::GeomLineSegment *lminor = new Part::GeomLineSegment();
            lminor->setPoints(minorpositiveend,minornegativeend);

            igeo.push_back(lminor);

            Sketcher::Constraint *newConstr = new Sketcher::Constraint();
            newConstr->Type = Sketcher::InternalAlignment;
            newConstr->AlignmentType = EllipseMinorDiameter;
            newConstr->First = currentgeoid+incrgeo+1;
            newConstr->Second = GeoId;

            icon.push_back(newConstr);
            incrgeo++;
        }
        if(!focus1)
        {
            Part::GeomPoint *pf1 = new Part::GeomPoint();
            pf1->setPoint(focus1P);

            igeo.push_back(pf1);

            Sketcher::Constraint *newConstr = new Sketcher::Constraint();
            newConstr->Type = Sketcher::InternalAlignment;
            newConstr->AlignmentType = EllipseFocus1;
            newConstr->First = currentgeoid+incrgeo+1;
            newConstr->FirstPos = Sketcher::PointPos::start;
            newConstr->Second = GeoId;

            icon.push_back(newConstr);
            incrgeo++;
        }
        if(!focus2)
        {
            Part::GeomPoint *pf2 = new Part::GeomPoint();
            pf2->setPoint(focus2P);
            igeo.push_back(pf2);

            Sketcher::Constraint *newConstr = new Sketcher::Constraint();
            newConstr->Type = Sketcher::InternalAlignment;
            newConstr->AlignmentType = EllipseFocus2;
            newConstr->First = currentgeoid+incrgeo+1;
            newConstr->FirstPos = Sketcher::PointPos::start;
            newConstr->Second = GeoId;

            icon.push_back(newConstr);
        }

        this->addGeometry(igeo,true);
        this->addConstraints(icon);

        for (std::vector<Part::Geometry *>::iterator it=igeo.begin(); it != igeo.end(); ++it) {
            if (*it)
                delete *it;
        }

        for (std::vector<Constraint *>::iterator it=icon.begin(); it != icon.end(); ++it) {
            if (*it)
                delete *it;
        }

        icon.clear();
        igeo.clear();

        return incrgeo; //number of added elements
    }
    else if(geo->getTypeId() == Part::GeomArcOfHyperbola::getClassTypeId()) {
        // First we search what has to be restored
        bool major=false;
        bool minor=false;
        bool focus=false;

        const std::vector< Sketcher::Constraint * > &vals = Constraints.getValues();

        for (std::vector< Sketcher::Constraint * >::const_iterator it= vals.begin();
             it != vals.end(); ++it) {
            if((*it)->Type == Sketcher::InternalAlignment && (*it)->Second == GeoId)
            {
                switch((*it)->AlignmentType){
                    case Sketcher::HyperbolaMajor:
                        major=true;
                        break;
                    case Sketcher::HyperbolaMinor:
                        minor=true;
                        break;
                    case Sketcher::HyperbolaFocus:
                        focus=true;
                        break;
                    default:
                        return -1;
                }
            }
        }

        int currentgeoid= getHighestCurveIndex();
        int incrgeo= 0;

        const Part::GeomArcOfHyperbola *aoh = static_cast<const Part::GeomArcOfHyperbola *>(geo);

        Base::Vector3d center = aoh->getCenter();
        double majord = aoh->getMajorRadius();
        double minord = aoh->getMinorRadius();
        Base::Vector3d majdir = aoh->getMajorAxisDir();

        std::vector<Part::Geometry *> igeo;
        std::vector<Constraint *> icon;

        Base::Vector3d mindir = Vector3d(-majdir.y, majdir.x);

        Base::Vector3d majorpositiveend = center + majord * majdir;
        Base::Vector3d majornegativeend = center - majord * majdir;
        Base::Vector3d minorpositiveend = majorpositiveend + minord * mindir;
        Base::Vector3d minornegativeend = majorpositiveend - minord * mindir;

        double df= sqrt(majord*majord+minord*minord);

        Base::Vector3d focus1P = center + df * majdir;

        if(!major)
        {
            Part::GeomLineSegment *lmajor = new Part::GeomLineSegment();
            lmajor->setPoints(majorpositiveend,majornegativeend);

            igeo.push_back(lmajor);

            Sketcher::Constraint *newConstr = new Sketcher::Constraint();
            newConstr->Type = Sketcher::InternalAlignment;
            newConstr->AlignmentType = Sketcher::HyperbolaMajor;
            newConstr->First = currentgeoid+incrgeo+1;
            newConstr->Second = GeoId;

            icon.push_back(newConstr);
            incrgeo++;
        }
        if(!minor)
        {
            Part::GeomLineSegment *lminor = new Part::GeomLineSegment();
            lminor->setPoints(minorpositiveend,minornegativeend);

            igeo.push_back(lminor);

            Sketcher::Constraint *newConstr = new Sketcher::Constraint();
            newConstr->Type = Sketcher::InternalAlignment;
            newConstr->AlignmentType = Sketcher::HyperbolaMinor;
            newConstr->First = currentgeoid+incrgeo+1;
            newConstr->Second = GeoId;

            icon.push_back(newConstr);

            incrgeo++;
        }
        if(!focus)
        {
            Part::GeomPoint *pf1 = new Part::GeomPoint();
            pf1->setPoint(focus1P);

            igeo.push_back(pf1);

            Sketcher::Constraint *newConstr = new Sketcher::Constraint();
            newConstr->Type = Sketcher::InternalAlignment;
            newConstr->AlignmentType = Sketcher::HyperbolaFocus;
            newConstr->First = currentgeoid+incrgeo+1;
            newConstr->FirstPos = Sketcher::PointPos::start;
            newConstr->Second = GeoId;

            icon.push_back(newConstr);
            incrgeo++;
        }

        this->addGeometry(igeo,true);
        this->addConstraints(icon);

        for (std::vector<Part::Geometry *>::iterator it=igeo.begin(); it != igeo.end(); ++it)
            if (*it)
                delete *it;

        for (std::vector<Constraint *>::iterator it=icon.begin(); it != icon.end(); ++it)
            if (*it)
                delete *it;

        icon.clear();
        igeo.clear();

        return incrgeo; //number of added elements
    }
    else if(geo->getTypeId() == Part::GeomArcOfParabola::getClassTypeId()) {
        // First we search what has to be restored
        bool focus=false;
        bool focus_to_vertex=false;

        const std::vector< Sketcher::Constraint * > &vals = Constraints.getValues();

        for (std::vector< Sketcher::Constraint * >::const_iterator it= vals.begin();
             it != vals.end(); ++it) {
            if((*it)->Type == Sketcher::InternalAlignment && (*it)->Second == GeoId)
            {
                switch((*it)->AlignmentType){
                    case Sketcher::ParabolaFocus:
                        focus=true;
                        break;
                    case Sketcher::ParabolaFocalAxis:
                        focus_to_vertex = true;
                        break;
                    default:
                        return -1;
                }
            }
        }

        int currentgeoid= getHighestCurveIndex();
        int incrgeo= 0;

        const Part::GeomArcOfParabola *aop = static_cast<const Part::GeomArcOfParabola *>(geo);

        Base::Vector3d center = aop->getCenter();
        Base::Vector3d focusp = aop->getFocus();

        std::vector<Part::Geometry *> igeo;
        std::vector<Constraint *> icon;

       if (!focus) {
            Part::GeomPoint *pf1 = new Part::GeomPoint();
            pf1->setPoint(focusp);

            igeo.push_back(pf1);

            Sketcher::Constraint *newConstr = new Sketcher::Constraint();
            newConstr->Type = Sketcher::InternalAlignment;
            newConstr->AlignmentType = Sketcher::ParabolaFocus;
            newConstr->First = currentgeoid+incrgeo+1;
            newConstr->FirstPos = Sketcher::PointPos::start;
            newConstr->Second = GeoId;

            icon.push_back(newConstr);
            incrgeo++;
        }

       if (!focus_to_vertex) {
            Part::GeomLineSegment *paxis = new Part::GeomLineSegment();
            paxis->setPoints(center,focusp);

            igeo.push_back(paxis);

            Sketcher::Constraint *newConstr = new Sketcher::Constraint();
            newConstr->Type = Sketcher::InternalAlignment;
            newConstr->AlignmentType = Sketcher::ParabolaFocalAxis;
            newConstr->First = currentgeoid+incrgeo+1;
            newConstr->FirstPos = Sketcher::PointPos::none;
            newConstr->Second = GeoId;

            icon.push_back(newConstr);

            incrgeo++;
        }

        this->addGeometry(igeo,true);
        this->addConstraints(icon);

        for (std::vector<Part::Geometry *>::iterator it=igeo.begin(); it != igeo.end(); ++it) {
            if (*it)
                delete *it;
        }

        for (std::vector<Constraint *>::iterator it=icon.begin(); it != icon.end(); ++it) {
            if (*it)
                delete *it;
        }

        icon.clear();
        igeo.clear();

        return incrgeo; //number of added elements
    }
    else if(geo->getTypeId() == Part::GeomBSplineCurve::getClassTypeId()) {

        const Part::GeomBSplineCurve *bsp = static_cast<const Part::GeomBSplineCurve *>(geo);
        // First we search what has to be restored
        std::vector<bool> controlpoints(bsp->countPoles());
        std::vector<int> controlpointgeoids(bsp->countPoles());

        std::vector<bool> knotpoints(bsp->countKnots());
        std::vector<int> knotgeoids(bsp->countKnots());

        bool isfirstweightconstrained = false;

        std::vector<bool>::iterator itb;
        std::vector<int>::iterator it;

        for(it=controlpointgeoids.begin(), itb=controlpoints.begin(); it!=controlpointgeoids.end() && itb!=controlpoints.end(); ++it, ++itb) {
            (*it)=-1;
            (*itb)=false;
        }

        for(it=knotgeoids.begin(), itb=knotpoints.begin(); it!=knotgeoids.end() && itb!=knotpoints.end(); ++it, ++itb) {
            (*it)=-1;
            (*itb)=false;
        }

        const std::vector< Sketcher::Constraint * > &vals = Constraints.getValues();

        // search for existing poles
        for (std::vector< Sketcher::Constraint * >::const_iterator it= vals.begin();
             it != vals.end(); ++it) {
            if((*it)->Type == Sketcher::InternalAlignment && (*it)->Second == GeoId)
            {
                switch((*it)->AlignmentType){
                    case Sketcher::BSplineControlPoint:
                        controlpoints[(*it)->InternalAlignmentIndex] = true;
                        controlpointgeoids[(*it)->InternalAlignmentIndex] = (*it)->First;
                        break;
                    case Sketcher::BSplineKnotPoint:
                        knotpoints[(*it)->InternalAlignmentIndex] = true;
                        knotgeoids[(*it)->InternalAlignmentIndex] = (*it)->First;
                        break;
                    default:
                        return -1;
                }
            }
        }

        if(controlpoints[0]) {
            // search for first pole weight constraint
            for (std::vector< Sketcher::Constraint * >::const_iterator it= vals.begin();
                it != vals.end(); ++it) {
                if((*it)->Type == Sketcher::Weight && (*it)->First == controlpointgeoids[0]) {
                    isfirstweightconstrained = true ;
                }
            }
        }

        int currentgeoid = getHighestCurveIndex();
        int incrgeo = 0;

        std::vector<Part::Geometry *> igeo;
        std::vector<Constraint *> icon;

        std::vector<Base::Vector3d> poles = bsp->getPoles();
        std::vector<double> weights = bsp->getWeights();
        std::vector<double> knots = bsp->getKnots();

        double distance_p0_p1 = (poles[1]-poles[0]).Length(); // for visual purposes only

        int index=0;

        for(it=controlpointgeoids.begin(), itb=controlpoints.begin(); it!=controlpointgeoids.end() && itb!=controlpoints.end(); ++it, ++itb, index++) {

            if(!(*itb)) // if controlpoint not existing
            {
                Part::GeomCircle *pc = new Part::GeomCircle();
                pc->setCenter(poles[index]);
                pc->setRadius(distance_p0_p1/6);

                igeo.push_back(pc);

                Sketcher::Constraint *newConstr = new Sketcher::Constraint();
                newConstr->Type = Sketcher::InternalAlignment;
                newConstr->AlignmentType = Sketcher::BSplineControlPoint;
                newConstr->First = currentgeoid+incrgeo+1;
                newConstr->FirstPos = Sketcher::PointPos::mid;
                newConstr->Second = GeoId;
                newConstr->InternalAlignmentIndex = index;

                icon.push_back(newConstr);

                if(it != controlpointgeoids.begin()) {
                    if(isfirstweightconstrained && weights[0] == weights[index]) {
                        // if pole-weight newly created AND first weight is radius-constrained,
                        // AND these weights are equal, constrain them to be equal
                        Sketcher::Constraint *newConstr2 = new Sketcher::Constraint();
                        newConstr2->Type = Sketcher::Equal;
                        newConstr2->First = currentgeoid+incrgeo+1;
                        newConstr2->FirstPos = Sketcher::PointPos::none;
                        newConstr2->Second = controlpointgeoids[0];
                        newConstr2->SecondPos = Sketcher::PointPos::none;

                        icon.push_back(newConstr2);
                    }
                }
                else {
                    controlpointgeoids[0] = currentgeoid+incrgeo+1;
                    if (weights[0] == 1.0) {
                        // if the first weight is 1.0 it's probably going to be non-rational
                        Sketcher::Constraint *newConstr3 = new Sketcher::Constraint();
                        newConstr3->Type = Sketcher::Weight;
                        newConstr3->First = controlpointgeoids[0];
                        newConstr3->setValue(weights[0]);

                        icon.push_back(newConstr3);

                        isfirstweightconstrained = true;
                    }
                }
                incrgeo++;
            }
        }

        index=0;

        for(it=knotgeoids.begin(), itb=knotpoints.begin(); it!=knotgeoids.end() && itb!=knotpoints.end(); ++it, ++itb, index++) {

            if(!(*itb)) // if knot point not existing
            {
                Part::GeomPoint *kp = new Part::GeomPoint();

                kp->setPoint(bsp->pointAtParameter(knots[index]));

                igeo.push_back(kp);

                Sketcher::Constraint *newConstr = new Sketcher::Constraint();
                newConstr->Type = Sketcher::InternalAlignment;
                newConstr->AlignmentType = Sketcher::BSplineKnotPoint;
                newConstr->First = currentgeoid+incrgeo+1;
                newConstr->FirstPos = Sketcher::PointPos::start;
                newConstr->Second = GeoId;
                newConstr->InternalAlignmentIndex = index;

                icon.push_back(newConstr);

                incrgeo++;
            }
        }

        Q_UNUSED(isfirstweightconstrained);

        this->addGeometry(igeo,true);
        this->addConstraints(icon);

        for (std::vector<Part::Geometry *>::iterator it=igeo.begin(); it != igeo.end(); ++it)
            if (*it)
                delete *it;

        for (std::vector<Constraint *>::iterator it=icon.begin(); it != icon.end(); ++it)
            if (*it)
                delete *it;

        icon.clear();
        igeo.clear();

        return incrgeo; //number of added elements
    }
    else
        return -1; // not supported type
}

int SketchObject::deleteUnusedInternalGeometry(int GeoId, bool delgeoid)
{
   if (GeoId < 0 || GeoId > getHighestCurveIndex())
        return -1;

    const Part::Geometry *geo = getGeometry(GeoId);
    // Only for supported types
    if (geo->getTypeId() == Part::GeomEllipse::getClassTypeId() ||
        geo->getTypeId() == Part::GeomArcOfEllipse::getClassTypeId() ||
        geo->getTypeId() == Part::GeomArcOfHyperbola::getClassTypeId()) {

        int majorelementindex=-1;
        int minorelementindex=-1;
        int focus1elementindex=-1;
        int focus2elementindex=-1;

        const std::vector< Sketcher::Constraint * > &vals = Constraints.getValues();

        for (std::vector< Sketcher::Constraint * >::const_iterator it = vals.begin();
                it != vals.end(); ++it) {
            if((*it)->Type == Sketcher::InternalAlignment && (*it)->Second == GeoId)
            {
                switch((*it)->AlignmentType){
                    case Sketcher::EllipseMajorDiameter:
                    case Sketcher::HyperbolaMajor:
                        majorelementindex=(*it)->First;
                        break;
                    case Sketcher::EllipseMinorDiameter:
                    case Sketcher::HyperbolaMinor:
                        minorelementindex=(*it)->First;
                        break;
                    case Sketcher::EllipseFocus1:
                    case Sketcher::HyperbolaFocus:
                        focus1elementindex=(*it)->First;
                        break;
                    case Sketcher::EllipseFocus2:
                        focus2elementindex=(*it)->First;
                        break;
                    default:
                        return -1;
                }
            }
        }

        // Hide unused geometry here
        int majorconstraints=0; // number of constraints associated to the geoid of the major axis
        int minorconstraints=0;
        int focus1constraints=0;
        int focus2constraints=0;

        for (std::vector< Sketcher::Constraint * >::const_iterator it= vals.begin();
            it != vals.end(); ++it) {

            if((*it)->Second == majorelementindex || (*it)->First == majorelementindex || (*it)->Third == majorelementindex)
                majorconstraints++;
            else if((*it)->Second == minorelementindex || (*it)->First == minorelementindex || (*it)->Third == minorelementindex)
                minorconstraints++;
            else if((*it)->Second == focus1elementindex || (*it)->First == focus1elementindex || (*it)->Third == focus1elementindex)
                focus1constraints++;
            else if((*it)->Second == focus2elementindex || (*it)->First == focus2elementindex || (*it)->Third == focus2elementindex)
                focus2constraints++;
        }

        std::vector<int> delgeometries;

        // those with less than 2 constraints must be removed
        if (focus2constraints<2)
            delgeometries.push_back(focus2elementindex);

        if (focus1constraints<2)
            delgeometries.push_back(focus1elementindex);

        if (minorconstraints<2)
            delgeometries.push_back(minorelementindex);

        if (majorconstraints<2)
            delgeometries.push_back(majorelementindex);

        if(delgeoid)
            delgeometries.push_back(GeoId);

        std::sort(delgeometries.begin(), delgeometries.end()); // indices over an erased element get automatically updated!!

        if (!delgeometries.empty()) {
            for (std::vector<int>::reverse_iterator it=delgeometries.rbegin(); it!=delgeometries.rend(); ++it) {
                delGeometry(*it,false);
            }
        }

        int ndeleted =  delgeometries.size();

        delgeometries.clear();

        return ndeleted; //number of deleted elements
    }
    else if( geo->getTypeId() == Part::GeomArcOfParabola::getClassTypeId()) {
        // if the focus-to-vertex line is constrained, then never delete the focus
        // if the line is unconstrained, then the line may be deleted,
        // in this case the focus may be deleted if unconstrained.
        int majorelementindex=-1;
        int focus1elementindex=-1;

        const std::vector< Sketcher::Constraint * > &vals = Constraints.getValues();

        for (std::vector< Sketcher::Constraint * >::const_iterator it= vals.begin(); it != vals.end(); ++it) {
            if ((*it)->Type == Sketcher::InternalAlignment && (*it)->Second == GeoId) {
                switch ((*it)->AlignmentType) {
                case Sketcher::ParabolaFocus:
                    focus1elementindex = (*it)->First;
                    break;
                case Sketcher::ParabolaFocalAxis:
                    majorelementindex = (*it)->First;
                    break;
                default:
                    return -1;
                }
            }
        }

        // Hide unused geometry here
        int majorconstraints=0; // number of constraints associated to the geoid of the major axis other than the coincident ones
        int focus1constraints=0;

        for (std::vector< Sketcher::Constraint * >::const_iterator it= vals.begin(); it != vals.end(); ++it) {
            if( (*it)->Second == majorelementindex ||
                (*it)->First == majorelementindex  ||
                (*it)->Third == majorelementindex)
                majorconstraints++;
            else if ((*it)->Second == focus1elementindex ||
                (*it)->First == focus1elementindex ||
                (*it)->Third == focus1elementindex)
                focus1constraints++;
        }

        std::vector<int> delgeometries;

        // major has minimum one constraint, the specific internal alignment constraint
        if (majorelementindex !=-1 && majorconstraints<2)
            delgeometries.push_back(majorelementindex);

        // focus has minimum one constraint now, the specific internal alignment constraint
        if (focus1elementindex !=-1 && focus1constraints<2)
            delgeometries.push_back(focus1elementindex);

        if(delgeoid)
            delgeometries.push_back(GeoId);

        std::sort(delgeometries.begin(), delgeometries.end()); // indices over an erased element get automatically updated!!

        if (!delgeometries.empty()) {
            for (std::vector<int>::reverse_iterator it=delgeometries.rbegin(); it!=delgeometries.rend(); ++it) {
                delGeometry(*it,false);
            }
        }

        int ndeleted =  delgeometries.size();

        delgeometries.clear();

        return ndeleted; //number of deleted elements
    }
    else if (geo->getTypeId() == Part::GeomBSplineCurve::getClassTypeId()) {

        const Part::GeomBSplineCurve *bsp = static_cast<const Part::GeomBSplineCurve *>(geo);

        // First we search existing IA
        std::vector<int> controlpointgeoids(bsp->countPoles());
        std::vector<int> cpassociatedconstraints(bsp->countPoles());

        std::vector<int> knotgeoids(bsp->countKnots());
        std::vector<int> kassociatedconstraints(bsp->countKnots());

        std::vector<int>::iterator it;
        std::vector<int>::iterator ita;

        for (it=controlpointgeoids.begin(), ita=cpassociatedconstraints.begin(); it!=controlpointgeoids.end() && ita!=cpassociatedconstraints.end(); ++it, ++ita) {
            (*it) = -1;
            (*ita) = 0;
        }

        for (it=knotgeoids.begin(), ita=kassociatedconstraints.begin(); it!=knotgeoids.end() && ita!=kassociatedconstraints.end(); ++it, ++ita) {
            (*it) = -1;
            (*ita) = 0;
        }

        const std::vector< Sketcher::Constraint * > &vals = Constraints.getValues();

        // search for existing poles
        for (std::vector< Sketcher::Constraint * >::const_iterator jt = vals.begin(); jt != vals.end(); ++jt) {
            if ((*jt)->Type == Sketcher::InternalAlignment && (*jt)->Second == GeoId) {
                switch ((*jt)->AlignmentType) {
                case Sketcher::BSplineControlPoint:
                    controlpointgeoids[(*jt)->InternalAlignmentIndex] = (*jt)->First;
                    break;
                case Sketcher::BSplineKnotPoint:
                    knotgeoids[(*jt)->InternalAlignmentIndex] = (*jt)->First;
                    break;
                default:
                    return -1;
                }
            }
        }

        std::vector<int> delgeometries;

        for (it=controlpointgeoids.begin(), ita=cpassociatedconstraints.begin(); it!=controlpointgeoids.end() && ita!=cpassociatedconstraints.end(); ++it, ++ita) {
            if ((*it) != -1) {
                // look for a circle at geoid index
                for (std::vector< Sketcher::Constraint * >::const_iterator itc= vals.begin(); itc != vals.end(); ++itc) {

                    if ( (*itc)->Type==Sketcher::Equal ) {
                        bool f=false,s=false;
                        for ( std::vector<int>::iterator its=controlpointgeoids.begin(); its!=controlpointgeoids.end(); ++its) {
                            if( (*itc)->First == *its ) {
                                f=true;
                            }
                            else if ( (*itc)->Second == *its ) {
                                s=true;
                            }

                            if (f && s) { // the equality constraint is not interpole
                                break;
                            }
                        }

                        if (f != s) { // the equality constraint constraints a pole but it is not interpole
                            (*ita)++;
                        }

                    }
                    // We do not ignore weight constraints as we did with radius constraints, because the radius magnitude no longer makes sense
                    // without the B-Spline.
                }

                if ( (*ita) < 2 ) { // IA
                    delgeometries.push_back((*it));
                }
            }
        }

        for (it=knotgeoids.begin(), ita=kassociatedconstraints.begin(); it!=knotgeoids.end() && ita!=kassociatedconstraints.end(); ++it, ++ita) {
            if ((*it) != -1) {
                // look for a point at geoid index
                for (std::vector< Sketcher::Constraint * >::const_iterator itc= vals.begin(); itc != vals.end(); ++itc) {
                    if ((*itc)->Second == (*it) || (*itc)->First == (*it) || (*itc)->Third == (*it)) {
                        (*ita)++;
                    }
                }

                if ( (*ita) < 2 ) { // IA
                    delgeometries.push_back((*it));
                }
            }
        }


        if(delgeoid)
            delgeometries.push_back(GeoId);

        int ndeleted = delGeometriesExclusiveList(delgeometries);

        return ndeleted; //number of deleted elements
    }
    else {
        return -1; // not supported type
    }
}

bool SketchObject::convertToNURBS(int GeoId)
{
    Base::StateLocker lock(managedoperation, true); // no need to check input data validity as this is an sketchobject managed operation.

    if (GeoId > getHighestCurveIndex() ||
        (GeoId < 0 && -GeoId > static_cast<int>(ExternalGeo.size())) ||
        GeoId == -1 || GeoId == -2)
        return false;

    const Part::Geometry *geo = getGeometry(GeoId);

    if(geo->getTypeId() == Part::GeomPoint::getClassTypeId())
        return false;

    const Part::GeomCurve *geo1 = static_cast<const Part::GeomCurve *>(geo);

    Part::GeomBSplineCurve* bspline;

    try {
        bspline = geo1->toNurbs(geo1->getFirstParameter(), geo1->getLastParameter());

        if(geo1->isDerivedFrom(Part::GeomArcOfConic::getClassTypeId())){
            const Part::GeomArcOfConic * geoaoc = static_cast<const Part::GeomArcOfConic *>(geo1);

            if(geoaoc->isReversed())
                bspline->reverse();
        }
    }
    catch (const Base::Exception& e) {
        Base::Console().Error("%s\n", e.what());
        // revert to original values
        return false;
    }

    const std::vector< Part::Geometry * > &vals = getInternalGeometry();

    std::vector< Part::Geometry * > newVals(vals);

    // Block checks and updates in OnChanged to avoid unnecessary checks and updates
    {
        Base::StateLocker lock(internaltransaction, true);

        if (GeoId < 0) { // external geometry
            newVals.push_back(bspline);
        }
        else { // normal geometry

            newVals[GeoId] = bspline;

            const std::vector< Sketcher::Constraint * > &cvals = Constraints.getValues();

            std::vector< Constraint * > newcVals(cvals);

            int index = cvals.size()-1;
            // delete constraints on this elements other than coincident constraints (bspline does not support them currently), except
            // for coincidents on mid point of the to-be-converted curve.
            for (; index >= 0; index--) {
                auto otherthancoincident =  cvals[index]->Type != Sketcher::Coincident &&
                                            (cvals[index]->First == GeoId || cvals[index]->Second == GeoId || cvals[index]->Third == GeoId);

                auto coincidentonmidpoint = cvals[index]->Type == Sketcher::Coincident &&
                                            (   (cvals[index]->First == GeoId && cvals[index]->FirstPos == Sketcher::PointPos::mid) ||
                                                (cvals[index]->Second == GeoId && cvals[index]->SecondPos == Sketcher::PointPos::mid) );

                if (otherthancoincident || coincidentonmidpoint)
                    newcVals.erase(newcVals.begin()+index);

            }

            this->Constraints.setValues(std::move(newcVals));
        }

        Geometry.setValues(std::move(newVals));
    }

    // trigger update now
    // Update geometry indices and rebuild vertexindex now via onChanged, so that ViewProvider::UpdateData is triggered.
    Geometry.touch();

    return true;

}

bool SketchObject::increaseBSplineDegree(int GeoId, int degreeincrement /*= 1*/)
{
    Base::StateLocker lock(managedoperation, true); // no need to check input data validity as this is an sketchobject managed operation.

    if (GeoId < 0 || GeoId > getHighestCurveIndex())
        return false;

    const Part::Geometry *geo = getGeometry(GeoId);

    if (geo->getTypeId() != Part::GeomBSplineCurve::getClassTypeId())
        return false;

    const Part::GeomBSplineCurve *bsp = static_cast<const Part::GeomBSplineCurve *>(geo);

    const Handle(Geom_BSplineCurve) curve = Handle(Geom_BSplineCurve)::DownCast(bsp->handle());

    std::unique_ptr<Part::GeomBSplineCurve> bspline(new Part::GeomBSplineCurve(curve));

    try {
        int cdegree = bspline->getDegree();

        bspline->increaseDegree(cdegree+degreeincrement);
    }
    catch (const Base::Exception& e) {
        Base::Console().Error("%s\n", e.what());
        return false;
    }

    const std::vector< Part::Geometry * > &vals = getInternalGeometry();

    std::vector< Part::Geometry * > newVals(vals);

    newVals[GeoId] = bspline.release();

    // AcceptGeometry called from onChanged
    Geometry.setValues(std::move(newVals));

    return true;
}

bool SketchObject::decreaseBSplineDegree(int GeoId, int degreedecrement /*= 1*/)
{
    Base::StateLocker lock(managedoperation, true); // no need to check input data validity as this is an sketchobject managed operation.

    if (GeoId < 0 || GeoId > getHighestCurveIndex())
        return false;

    const Part::Geometry *geo = getGeometry(GeoId);

    if (geo->getTypeId() != Part::GeomBSplineCurve::getClassTypeId())
        return false;

    const Part::GeomBSplineCurve *bsp = static_cast<const Part::GeomBSplineCurve *>(geo);

    const Handle(Geom_BSplineCurve) curve = Handle(Geom_BSplineCurve)::DownCast(bsp->handle());

    std::unique_ptr<Part::GeomBSplineCurve> bspline(new Part::GeomBSplineCurve(curve));

    try {
        int cdegree = bspline->getDegree();

        // degree must be >= 1
        int maxdegree = cdegree - degreedecrement;
        if (maxdegree == 0)
            return false;
        bool ok = bspline->approximate(Precision::Confusion(), 20, maxdegree, 0);
        if (!ok)
            return false;
    }
    catch (const Base::Exception& e) {
        Base::Console().Error("%s\n", e.what());
        return false;
    }

    // FIXME: Avoid to delete the whole geometry but only delete invalid constraints
    // and unused construction geometries
#if 0
    const std::vector< Part::Geometry * > &vals = getInternalGeometry();

    std::vector< Part::Geometry * > newVals(vals);

    newVals[GeoId] = bspline.release();

    // AcceptGeometry called from onChanged
    Geometry.setValues(newVals);
#else
    delGeometry(GeoId);
    int newId = addGeometry(bspline.release());
    exposeInternalGeometry(newId);
#endif

    return true;
}

bool SketchObject::modifyBSplineKnotMultiplicity(int GeoId, int knotIndex, int multiplicityincr)
{
    Base::StateLocker lock(managedoperation, true); // no need to check input data validity as this is an sketchobject managed operation.

    if (GeoId < 0 || GeoId > getHighestCurveIndex())
        THROWMT(Base::ValueError,QT_TRANSLATE_NOOP("Exceptions", "BSpline Geometry Index (GeoID) is out of bounds."))

    if (multiplicityincr == 0) // no change in multiplicity
        THROWMT(Base::ValueError,QT_TRANSLATE_NOOP("Exceptions", "You are requesting no change in knot multiplicity."))

    const Part::Geometry *geo = getGeometry(GeoId);

    if(geo->getTypeId() != Part::GeomBSplineCurve::getClassTypeId())
        THROWMT(Base::TypeError,QT_TRANSLATE_NOOP("Exceptions", "The Geometry Index (GeoId) provided is not a B-spline curve."))

    const Part::GeomBSplineCurve *bsp = static_cast<const Part::GeomBSplineCurve *>(geo);

    int degree = bsp->getDegree();

    if( knotIndex > bsp->countKnots() || knotIndex < 1 ) // knotindex in OCC 1 -> countKnots
        THROWMT(Base::ValueError,QT_TRANSLATE_NOOP("Exceptions", "The knot index is out of bounds. Note that in accordance with OCC notation, the first knot has index 1 and not zero."))

    std::unique_ptr<Part::GeomBSplineCurve> bspline;

    int curmult = bsp->getMultiplicity(knotIndex);

    if ( (curmult + multiplicityincr) > degree ) // zero is removing the knot, degree is just positional continuity
        THROWMT(Base::ValueError,QT_TRANSLATE_NOOP("Exceptions","The multiplicity cannot be increased beyond the degree of the B-spline."))

    if ( (curmult + multiplicityincr) < 0) // zero is removing the knot, degree is just positional continuity
        THROWMT(Base::ValueError,QT_TRANSLATE_NOOP("Exceptions", "The multiplicity cannot be decreased beyond zero."))

    try {
        bspline.reset(static_cast<Part::GeomBSplineCurve *>(bsp->clone()));

        if(multiplicityincr > 0) { // increase multiplicity
            bspline->increaseMultiplicity(knotIndex, curmult + multiplicityincr);
        }
        else { // decrease multiplicity
            bool result = bspline->removeKnot(knotIndex, curmult + multiplicityincr,1E6);

            if(!result)
                THROWMT(Base::CADKernelError, QT_TRANSLATE_NOOP("Exceptions", "OCC is unable to decrease the multiplicity within the maximum tolerance."))
        }
    }
    catch (const Base::Exception& e) {
        Base::Console().Error("%s\n", e.what());
        return false;
    }

    // we succeeded with the multiplicity modification, so alignment geometry may be invalid/inconsistent for the new bspline

    std::vector<int> delGeoId;

    std::vector<Base::Vector3d> poles = bsp->getPoles();
    std::vector<Base::Vector3d> newpoles = bspline->getPoles();
    std::vector<int> prevpole(bsp->countPoles());

    for(int i = 0; i < int(poles.size()); i++)
        prevpole[i] = -1;

    int taken = 0;
    for(int j = 0; j < int(poles.size()); j++){
        for(int i = taken; i < int(newpoles.size()); i++){
            if( newpoles[i] == poles[j] ) {
                prevpole[j] = i;
                taken++;
                break;
            }
        }
    }

    // on fully removing a knot the knot geometry changes
    std::vector<double> knots = bsp->getKnots();
    std::vector<double> newknots = bspline->getKnots();
    std::vector<int> prevknot(bsp->countKnots());

    for(int i = 0; i < int(knots.size()); i++)
        prevknot[i] = -1;

    taken = 0;
    for(int j = 0; j < int(knots.size()); j++){
        for(int i = taken; i < int(newknots.size()); i++){
            if( newknots[i] == knots[j] ) {
                prevknot[j] = i;
                taken++;
                break;
            }
        }
    }

    const std::vector< Sketcher::Constraint * > &cvals = Constraints.getValues();

    std::vector< Constraint * > newcVals(0);

    // modify pole constraints
    for (std::vector< Sketcher::Constraint * >::const_iterator it= cvals.begin(); it != cvals.end(); ++it) {
        if((*it)->Type == Sketcher::InternalAlignment && (*it)->Second == GeoId)
        {
            if((*it)->AlignmentType == Sketcher::BSplineControlPoint) {
                if (prevpole[(*it)->InternalAlignmentIndex]!=-1) {
                    assert(prevpole[(*it)->InternalAlignmentIndex] < bspline->countPoles());
                    Constraint * newConstr = (*it)->clone();
                    newConstr->InternalAlignmentIndex = prevpole[(*it)->InternalAlignmentIndex];
                    newcVals.push_back(newConstr);
                }
                else { // it is an internal alignment geometry that is no longer valid => delete it and the pole circle
                    delGeoId.push_back((*it)->First);
                }
            }
            else if((*it)->AlignmentType == Sketcher::BSplineKnotPoint) {
                if (prevknot[(*it)->InternalAlignmentIndex]!=-1) {
                    assert(prevknot[(*it)->InternalAlignmentIndex] < bspline->countKnots());
                    Constraint * newConstr = (*it)->clone();
                    newConstr->InternalAlignmentIndex = prevknot[(*it)->InternalAlignmentIndex];
                    newcVals.push_back(newConstr);
                }
                else { // it is an internal alignment geometry that is no longer valid => delete it and the knot point
                    delGeoId.push_back((*it)->First);
                }
            }
            else { // it is a bspline geometry, but not a controlpoint or knot
                newcVals.push_back(*it);
            }
        }
        else {
            newcVals.push_back(*it);
        }
    }

    const std::vector< Part::Geometry * > &vals = getInternalGeometry();

    std::vector< Part::Geometry * > newVals(vals);

    newVals[GeoId] = bspline.release();

    // Block acceptGeometry in OnChanged to avoid unnecessary checks and updates
    {
        Base::StateLocker lock(internaltransaction, true);
        Geometry.setValues(std::move(newVals));

        this->Constraints.setValues(std::move(newcVals));
    }

    // Trigger update now
    // Update geometry indices and rebuild vertexindex now via onChanged, so that ViewProvider::UpdateData is triggered.
    if (!delGeoId.empty()) {
        delGeometriesExclusiveList(delGeoId);
    }
    else {
        Geometry.touch();
    }

    // * DOCUMENTING OCC ISSUE OCC < 6.9.0
    // https://forum.freecadweb.org/viewtopic.php?f=10&t=9364&start=330#p162528
    //
    // A segmentation fault is generated:
    //Program received signal SIGSEGV, Segmentation fault.
    //#0 /lib/x86_64-linux-gnu/libc.so.6(+0x36cb0) [0x7f4b933bbcb0]
    //#1  0x7f4b0300ea14 in BSplCLib::BuildCache(double, double, bool, int, TColStd_Array1OfReal const&, TColgp_Array1OfPnt const&, TColStd_Array1OfReal const&, TColgp_Array1OfPnt&, TColStd_Array1OfReal&) from /usr/lib/x86_64-linux-gnu/libTKMath.so.10+0x484
    //#2  0x7f4b033f9582 in Geom_BSplineCurve::ValidateCache(double) from /usr/lib/x86_64-linux-gnu/libTKG3d.so.10+0x202
    //#3  0x7f4b033f2a7e in Geom_BSplineCurve::D0(double, gp_Pnt&) const from /usr/lib/x86_64-linux-gnu/libTKG3d.so.10+0xde
    //#4  0x7f4b033de1b5 in Geom_Curve::Value(double) const from /usr/lib/x86_64-linux-gnu/libTKG3d.so.10+0x25
    //#5  0x7f4b03423d73 in GeomLProp_CurveTool::Value(Handle(Geom_Curve) const&, double, gp_Pnt&) from /usr/lib/x86_64-linux-gnu/libTKG3d.so.10+0x13
    //#6  0x7f4b03427175 in GeomLProp_CLProps::SetParameter(double) from /usr/lib/x86_64-linux-gnu/libTKG3d.so.10+0x75
    //#7  0x7f4b0342727d in GeomLProp_CLProps::GeomLProp_CLProps(Handle(Geom_Curve) const&, double, int, double) from /usr/lib/x86_64-linux-gnu/libTKG3d.so.10+0xcd
    //#8  0x7f4b11924b53 in Part::GeomCurve::pointAtParameter(double) const from /home/abdullah/github/freecad-build/Mod/Part/Part.so+0xa7



    return true;
}

bool SketchObject::insertBSplineKnot(int GeoId, double param, int multiplicity)
{
    Base::StateLocker lock(managedoperation, true); // TODO: Check if this is still valid: no need to check input data validity as this is an sketchobject managed operation.

    // handling unacceptable cases
    if (GeoId < 0 || GeoId > getHighestCurveIndex())
        THROWMT(Base::ValueError,QT_TRANSLATE_NOOP("Exceptions", "BSpline Geometry Index (GeoID) is out of bounds."));

    if (multiplicity == 0)
        THROWMT(Base::ValueError,QT_TRANSLATE_NOOP("Exceptions", "Knot cannot have zero multiplicity."));

    const Part::Geometry *geo = getGeometry(GeoId);

    if(geo->getTypeId() != Part::GeomBSplineCurve::getClassTypeId())
        THROWMT(Base::TypeError,QT_TRANSLATE_NOOP("Exceptions", "The Geometry Index (GeoId) provided is not a B-spline curve."));

    const Part::GeomBSplineCurve *bsp = static_cast<const Part::GeomBSplineCurve *>(geo);

    int degree = bsp->getDegree();
    double firstParam = bsp->getFirstParameter();
    double lastParam = bsp->getLastParameter();

    if (multiplicity > degree)
        THROWMT(Base::ValueError,QT_TRANSLATE_NOOP("Exceptions", "Knot multiplicity cannot be higher than the degree of the BSpline."));

    if (param > lastParam || param < firstParam)
        THROWMT(Base::ValueError,QT_TRANSLATE_NOOP("Exceptions", "Knot cannot be inserted outside the BSpline parameter range."));

    std::unique_ptr<Part::GeomBSplineCurve> bspline;

    // run the command
    try {
      bspline.reset(static_cast<Part::GeomBSplineCurve *>(bsp->clone()));

      bspline->insertKnot(param, multiplicity);
    }
    catch (const Base::Exception& e) {
      Base::Console().Error("%s\n", e.what());
      return false;
    }

    // once command is run update the internal geometries
    std::vector<int> delGeoId;

    std::vector<Base::Vector3d> poles = bsp->getPoles();
    std::vector<Base::Vector3d> newpoles = bspline->getPoles();
    std::vector<int> prevpole(bsp->countPoles());

    for(int i = 0; i < int(poles.size()); i++)
        prevpole[i] = -1;

    int taken = 0;
    for(int j = 0; j < int(poles.size()); j++){
        for(int i = taken; i < int(newpoles.size()); i++){
            if( newpoles[i] == poles[j] ) {
                prevpole[j] = i;
                taken++;
                break;
            }
        }
    }

    // on fully removing a knot the knot geometry changes
    std::vector<double> knots = bsp->getKnots();
    std::vector<double> newknots = bspline->getKnots();
    std::vector<int> prevknot(bsp->countKnots());

    for(int i = 0; i < int(knots.size()); i++)
        prevknot[i] = -1;

    taken = 0;
    for(int j = 0; j < int(knots.size()); j++){
        for(int i = taken; i < int(newknots.size()); i++){
            if( newknots[i] == knots[j] ) {
                prevknot[j] = i;
                taken++;
                break;
            }
        }
    }

    const std::vector< Sketcher::Constraint * > &cvals = Constraints.getValues();

    std::vector< Constraint * > newcVals(0);

    // modify pole constraints
    for (std::vector< Sketcher::Constraint * >::const_iterator it= cvals.begin(); it != cvals.end(); ++it) {
        if((*it)->Type == Sketcher::InternalAlignment && (*it)->Second == GeoId)
        {
            if((*it)->AlignmentType == Sketcher::BSplineControlPoint) {
                if (prevpole[(*it)->InternalAlignmentIndex]!=-1) {
                    assert(prevpole[(*it)->InternalAlignmentIndex] < bspline->countPoles());
                    Constraint * newConstr = (*it)->clone();
                    newConstr->InternalAlignmentIndex = prevpole[(*it)->InternalAlignmentIndex];
                    newcVals.push_back(newConstr);
                }
                else { // it is an internal alignment geometry that is no longer valid => delete it and the pole circle
                    delGeoId.push_back((*it)->First);
                }
            }
            else if((*it)->AlignmentType == Sketcher::BSplineKnotPoint) {
                if (prevknot[(*it)->InternalAlignmentIndex]!=-1) {
                    assert(prevknot[(*it)->InternalAlignmentIndex] < bspline->countKnots());
                    Constraint * newConstr = (*it)->clone();
                    newConstr->InternalAlignmentIndex = prevknot[(*it)->InternalAlignmentIndex];
                    newcVals.push_back(newConstr);
                }
                else { // it is an internal alignment geometry that is no longer valid => delete it and the knot point
                    delGeoId.push_back((*it)->First);
                }
            }
            else { // it is a bspline geometry, but not a controlpoint or knot
                newcVals.push_back(*it);
            }
        }
        else {
            newcVals.push_back(*it);
        }
    }

    const std::vector< Part::Geometry * > &vals = getInternalGeometry();

    std::vector< Part::Geometry * > newVals(vals);

    newVals[GeoId] = bspline.release();

    // Block acceptGeometry in OnChanged to avoid unnecessary checks and updates
    {
        Base::StateLocker lock(internaltransaction, true);
        Geometry.setValues(std::move(newVals));

        this->Constraints.setValues(std::move(newcVals));
    }

    // Trigger update now
    // Update geometry indices and rebuild vertexindex now via onChanged, so that ViewProvider::UpdateData is triggered.
    if (!delGeoId.empty()) {
        // NOTE: There have been a couple of instances when knot insertion has
        // led to a segmentation fault: see https://forum.freecadweb.org/viewtopic.php?f=19&t=64962&sid=10272db50a635c633260517b14ecad37.
        // If a segfault happens again and a `Geometry.touch()` here fixes it,
        // it is possible that `delGeometriesExclusiveList` is causing an update
        // in constraint GUI features during an intermediate step.
        // See 247a9f0876a00e08c25b07d1f8802479d8623e87 for suggestions.
        // Geometry.touch();
        delGeometriesExclusiveList(delGeoId);
    }
    else {
        Geometry.touch();
    }

    // handle this last return
    return true;
}

int SketchObject::carbonCopy(App::DocumentObject * pObj, bool construction)
{
    Base::StateLocker lock(managedoperation, true); // no need to check input data validity as this is an sketchobject managed operation.

    // so far only externals to the support of the sketch and datum features
    bool xinv = false, yinv = false;

    if (!isCarbonCopyAllowed(pObj->getDocument(), pObj, xinv, yinv))
        return -1;

    SketchObject * psObj = static_cast<SketchObject *>(pObj);

    const std::vector< Part::Geometry * > &vals = getInternalGeometry();

    const std::vector< Sketcher::Constraint * > &cvals = Constraints.getValues();

    std::vector< Part::Geometry * > newVals(vals);

    std::vector< Constraint * > newcVals(cvals);

    int nextgeoid = vals.size();

    int nextextgeoid = getExternalGeometryCount();

    int nextcid = cvals.size();

    const std::vector< Part::Geometry * > &svals = psObj->getInternalGeometry();

    const std::vector< Sketcher::Constraint * > &scvals = psObj->Constraints.getValues();

    newVals.reserve(vals.size()+svals.size());
    newcVals.reserve(cvals.size()+scvals.size());

    if(psObj->ExternalGeometry.getSize()>0) {
        std::vector<DocumentObject*> Objects     = ExternalGeometry.getValues();
        std::vector<std::string>     SubElements = ExternalGeometry.getSubValues();

        const std::vector<DocumentObject*> originalObjects = Objects;
        const std::vector<std::string>     originalSubElements = SubElements;

        std::vector<DocumentObject*> sObjects     = psObj->ExternalGeometry.getValues();
        std::vector<std::string>     sSubElements = psObj->ExternalGeometry.getSubValues();

        if (Objects.size() != SubElements.size() || sObjects.size() != sSubElements.size()) {
            assert(0 /*counts of objects and subelements in external geometry links do not match*/);
            Base::Console().Error("Internal error: counts of objects and subelements in external geometry links do not match\n");
            return -1;
        }

        int si=0;
        for (auto & sobj : sObjects) {
            int i=0;
            for (auto & obj : Objects){
                if (obj == sobj && SubElements[i] == sSubElements[si]){
                    Base::Console().Error("Link to %s already exists in this sketch. Delete the link and try again\n",sSubElements[si].c_str());
                    return -1;
                }

                i++;
            }

            Objects.push_back(sobj);
            SubElements.push_back(sSubElements[si]);

            si++;
        }

        ExternalGeometry.setValues(Objects,SubElements);

        try {
            rebuildExternalGeometry();
        }
        catch (const Base::Exception& e) {
            Base::Console().Error("%s\n", e.what());
            // revert to original values
            ExternalGeometry.setValues(originalObjects,originalSubElements);
            return -1;
        }

        solverNeedsUpdate=true;
    }

    for (std::vector<Part::Geometry *>::const_iterator it=svals.begin(); it != svals.end(); ++it){
        Part::Geometry *geoNew = (*it)->copy();
        if(construction && geoNew->getTypeId() != Part::GeomPoint::getClassTypeId()) {
            GeometryFacade::setConstruction(geoNew, true);
        }
        newVals.push_back(geoNew);
    }

    for (std::vector< Sketcher::Constraint * >::const_iterator it= scvals.begin(); it != scvals.end(); ++it) {
        Sketcher::Constraint *newConstr = (*it)->copy();
        if( (*it)->First>=0 )
            newConstr->First += nextgeoid;
        if( (*it)->Second>=0 )
            newConstr->Second += nextgeoid;
        if( (*it)->Third>=0 )
            newConstr->Third += nextgeoid;

        if( (*it)->First<-2 && (*it)->First != GeoEnum::GeoUndef )
            newConstr->First -= (nextextgeoid-2);
        if( (*it)->Second<-2 && (*it)->Second != GeoEnum::GeoUndef)
            newConstr->Second -= (nextextgeoid-2);
        if( (*it)->Third<-2 && (*it)->Third != GeoEnum::GeoUndef)
            newConstr->Third -= (nextextgeoid-2);

        newcVals.push_back(newConstr);
    }

    // Block acceptGeometry in OnChanged to avoid unnecessary checks and updates
    {
        Base::StateLocker lock(internaltransaction, true);
        Geometry.setValues(std::move(newVals));
        this->Constraints.setValues(std::move(newcVals));
    }
    // we trigger now the update (before dealing with expressions)
    // Update geometry indices and rebuild vertexindex now via onChanged, so that ViewProvider::UpdateData is triggered.
    Geometry.touch();

    int sourceid = 0;
    for (std::vector< Sketcher::Constraint * >::const_iterator it= scvals.begin(); it != scvals.end(); ++it, nextcid++, sourceid++) {

        if ((*it)->isDimensional()) {
            // then we link its value to the parent
            if ((*it)->isDriving) {
                App::ObjectIdentifier spath;
                std::shared_ptr<App::Expression> expr;
                std::string scname = (*it)->Name;
                if ( App::ExpressionParser::isTokenAnIndentifier(scname) ) {
                    spath = App::ObjectIdentifier(psObj->Constraints) << App::ObjectIdentifier::SimpleComponent(scname);
                    expr = std::shared_ptr<App::Expression>(App::Expression::parse(this, spath.getDocumentObjectName().getString() + spath.toString()));
                }
                else {
                    spath = psObj->Constraints.createPath(sourceid);
                    expr = std::shared_ptr<App::Expression>(App::Expression::parse(this, spath.getDocumentObjectName().getString() +std::string(1,'.') + spath.toString()));
                }
                // (there is a plausible alternative for a slightly different use case to copy the expression of the parent if one is existing)
                /*
                 *           App::PropertyExpressionEngine::ExpressionInfo expr_info = psObj->getExpression(path);
                 *
                 *           if (expr_info.expression)*/
                //App::Expression * expr = parse(this, const std::string& buffer);
                setExpression(Constraints.createPath(nextcid), expr);
            }
        }
    }

    return svals.size();
}

int SketchObject::addExternal(App::DocumentObject *Obj, const char* SubName)
{
    Base::StateLocker lock(managedoperation, true); // no need to check input data validity as this is an sketchobject managed operation.

    // so far only externals to the support of the sketch and datum features
    if (!isExternalAllowed(Obj->getDocument(), Obj))
       return -1;

    // get the actual lists of the externals
    std::vector<DocumentObject*> Objects     = ExternalGeometry.getValues();
    std::vector<std::string>     SubElements = ExternalGeometry.getSubValues();

    const std::vector<DocumentObject*> originalObjects = Objects;
    const std::vector<std::string>     originalSubElements = SubElements;

    if (Objects.size() != SubElements.size()) {
        assert(0 /*counts of objects and subelements in external geometry links do not match*/);
        Base::Console().Error("Internal error: counts of objects and subelements in external geometry links do not match\n");
        return -1;
    }

    for (size_t i = 0  ;  i < Objects.size()  ;  ++i){
        if (Objects[i] == Obj   &&   std::string(SubName) == SubElements[i]){
            Base::Console().Error("Link to %s already exists in this sketch.\n",SubName);
            return -1;
        }
    }

    // add the new ones
    Objects.push_back(Obj);
    SubElements.emplace_back(SubName);

    // set the Link list.
    ExternalGeometry.setValues(Objects,SubElements);
    try {
        rebuildExternalGeometry();
    }
    catch (const Base::Exception& e) {
        Base::Console().Error("%s\n", e.what());
        // revert to original values
        ExternalGeometry.setValues(originalObjects,originalSubElements);
        return -1;
    }

    acceptGeometry(); // This may need to be refactored into onChanged for ExternalGeometry

    solverNeedsUpdate=true;
    return ExternalGeometry.getValues().size()-1;
}

int SketchObject::delExternal(int ExtGeoId)
{
    Base::StateLocker lock(managedoperation, true); // no need to check input data validity as this is an sketchobject managed operation.

    // get the actual lists of the externals
    std::vector<DocumentObject*> Objects     = ExternalGeometry.getValues();
    std::vector<std::string>     SubElements = ExternalGeometry.getSubValues();

    if (ExtGeoId < 0 || ExtGeoId >= int(SubElements.size()))
        return -1;

    const std::vector<DocumentObject*> originalObjects = Objects;
    const std::vector<std::string>     originalSubElements = SubElements;

    Objects.erase(Objects.begin()+ExtGeoId);
    SubElements.erase(SubElements.begin()+ExtGeoId);

    const std::vector< Constraint * > &constraints = Constraints.getValues();
    std::vector< Constraint * > newConstraints;
    std::vector< Constraint * > copiedConstraints;
    int GeoId = GeoEnum::RefExt - ExtGeoId;
    for (auto cstr : constraints) {
        if (cstr->First != GeoId && cstr->Second != GeoId && cstr->Third != GeoId) {
            auto copiedConstr = cstr;
            if (copiedConstr->First < GeoId &&
                copiedConstr->First != GeoEnum::GeoUndef) {
                if (cstr == copiedConstr)
                    copiedConstr = cstr->clone();
                copiedConstr->First += 1;
            }
            if (copiedConstr->Second < GeoId &&
                copiedConstr->Second != GeoEnum::GeoUndef) {
                if (cstr == copiedConstr)
                    copiedConstr = cstr->clone();
                copiedConstr->Second += 1;
            }
            if (copiedConstr->Third < GeoId &&
                copiedConstr->Third != GeoEnum::GeoUndef) {
                if (cstr == copiedConstr)
                    copiedConstr = cstr->clone();
                copiedConstr->Third += 1;
            }

            newConstraints.push_back(copiedConstr);
            if (cstr != copiedConstr)
                copiedConstraints.push_back(copiedConstr);
        }
    }

    ExternalGeometry.setValues(Objects,SubElements);
    try {
        rebuildExternalGeometry();
    }
    catch (const Base::Exception& e) {
        Base::Console().Error("%s\n", e.what());
        // revert to original values
        ExternalGeometry.setValues(originalObjects,originalSubElements);
        for (Constraint* it : copiedConstraints)
            delete it;
        return -1;
    }

    solverNeedsUpdate=true;
    Constraints.setValues(std::move(newConstraints));
    acceptGeometry(); // This may need to be refactored into OnChanged for ExternalGeometry.
    return 0;
}

int SketchObject::delAllExternal()
{
    Base::StateLocker lock(managedoperation, true); // no need to check input data validity as this is an sketchobject managed operation.

    // get the actual lists of the externals
    std::vector<DocumentObject*> Objects     = ExternalGeometry.getValues();
    std::vector<std::string>     SubElements = ExternalGeometry.getSubValues();

    const std::vector<DocumentObject*> originalObjects = Objects;
    const std::vector<std::string>     originalSubElements = SubElements;

    Objects.clear();

    SubElements.clear();

    const std::vector< Constraint * > &constraints = Constraints.getValues();
    std::vector< Constraint * > newConstraints(0);

    for (std::vector<Constraint *>::const_iterator it = constraints.begin(); it != constraints.end(); ++it) {
        if ((*it)->First > GeoEnum::RefExt &&
            ((*it)->Second > GeoEnum::RefExt || (*it)->Second == GeoEnum::GeoUndef ) &&
            ((*it)->Third > GeoEnum::RefExt || (*it)->Third == GeoEnum::GeoUndef) ) {
            Constraint *copiedConstr = (*it)->clone();

            newConstraints.push_back(copiedConstr);
        }
    }

    ExternalGeometry.setValues(Objects,SubElements);
    try {
        rebuildExternalGeometry();
    }
    catch (const Base::Exception& e) {
        Base::Console().Error("%s\n", e.what());
        // revert to original values
        ExternalGeometry.setValues(originalObjects,originalSubElements);
        for (Constraint* it : newConstraints)
            delete it;
        return -1;
    }

    solverNeedsUpdate=true;
    Constraints.setValues(std::move(newConstraints));
    acceptGeometry(); // This may need to be refactored into OnChanged for ExternalGeometry
    return 0;
}

int SketchObject::delConstraintsToExternal()
{
    Base::StateLocker lock(managedoperation, true); // no need to check input data validity as this is an sketchobject managed operation.

    const std::vector< Constraint * > &constraints = Constraints.getValuesForce();
    std::vector< Constraint * > newConstraints(0);
    int GeoId = GeoEnum::RefExt, NullId = GeoEnum::GeoUndef;
    for (std::vector<Constraint *>::const_iterator it = constraints.begin();
         it != constraints.end(); ++it) {
        if (    (*it)->First > GeoId
                &&
                ((*it)->Second > GeoId || (*it)->Second == NullId)
                &&
                ((*it)->Third > GeoId || (*it)->Third == NullId)) {
            newConstraints.push_back(*it);
        }
    }

    Constraints.setValues(std::move(newConstraints));
    Constraints.acceptGeometry(getCompleteGeometry());

    if(noRecomputes) // if we do not have a recompute, the sketch must be solved to update the DoF of the solver
        solve();

    return 0;
}

int SketchObject::getCompleteGeometryIndex(int GeoId) const
{
    if (GeoId >= 0) {
        if (GeoId < int(Geometry.getSize()))
            return GeoId;
    }
    else if (-GeoId <= int(ExternalGeo.size()))
        return -GeoId-1;

    return GeoEnum::GeoUndef;
}

int SketchObject::getGeoIdFromCompleteGeometryIndex(int completeGeometryIndex) const
{
    int completeGeometryCount = int(Geometry.getSize()+ExternalGeo.size());

    if(completeGeometryIndex < 0 ||
        completeGeometryIndex >= completeGeometryCount)
        return GeoEnum::GeoUndef;

    if(completeGeometryIndex < Geometry.getSize())
        return completeGeometryIndex;
    else
        return (completeGeometryIndex - completeGeometryCount);
}

std::unique_ptr<const GeometryFacade> SketchObject::getGeometryFacade(int GeoId) const
{
    return GeometryFacade::getFacade(getGeometry(GeoId));
}

// Auxiliary Method: returns vector projection in UV space of plane
static gp_Vec2d ProjVecOnPlane_UV( const gp_Vec& V, const gp_Pln& Pl)
{
  return gp_Vec2d( V.Dot(Pl.Position().XDirection()),
                   V.Dot(Pl.Position().YDirection()));
}

// Auxiliary Method: returns vector projection in UVN space of plane
static gp_Vec ProjVecOnPlane_UVN( const gp_Vec& V, const gp_Pln& Pl)
{
  gp_Vec2d vector = ProjVecOnPlane_UV(V, Pl);
  return gp_Vec(vector.X(), vector.Y(), 0.0);
}

// Auxiliary Method: returns vector projection in XYZ space
#if 0
static gp_Vec ProjVecOnPlane_XYZ( const gp_Vec& V, const gp_Pln& Pl)
{
  return V.Dot(Pl.Position().XDirection()) * Pl.Position().XDirection() +
         V.Dot(Pl.Position().YDirection()) * Pl.Position().YDirection();
}
#endif

// Auxiliary Method: returns point projection in UV space of plane
static gp_Vec2d ProjPointOnPlane_UV( const gp_Pnt& P, const gp_Pln& Pl)
{
  gp_Vec OP = gp_Vec(Pl.Location(), P);
  return ProjVecOnPlane_UV(OP, Pl);
}

// Auxiliary Method: returns point projection in UVN space of plane
static gp_Vec ProjPointOnPlane_UVN(const gp_Pnt& P, const gp_Pln& Pl)
{
  gp_Vec2d vec2 = ProjPointOnPlane_UV(P, Pl);
  return gp_Vec(vec2.X(), vec2.Y(), 0.0);
}

// Auxiliary Method: returns point projection in XYZ space
static gp_Pnt ProjPointOnPlane_XYZ(const gp_Pnt& P, const gp_Pln& Pl)
{
   gp_Vec positionUVN = ProjPointOnPlane_UVN(P, Pl);
   return gp_Pnt((positionUVN.X() * Pl.Position().XDirection() + positionUVN.Y() * Pl.Position().YDirection() + gp_Vec(Pl.Location().XYZ())).XYZ());
}

// Auxiliary method
Part::Geometry* projectLine(const BRepAdaptor_Curve& curve, const Handle(Geom_Plane)& gPlane, const Base::Placement& invPlm)
{
    double first = curve.FirstParameter();

    if (fabs(first) > 1E99) {
        // TODO: What is OCE's definition of Infinite?
        // TODO: The clean way to do this is to handle a new sketch geometry Geom::Line
        // but its a lot of work to implement...
        first = -10000;
    }

    double last = curve.LastParameter();
    if (fabs(last) > 1E99) {
        last = +10000;
    }

    gp_Pnt P1 = curve.Value(first);
    gp_Pnt P2 = curve.Value(last);

    GeomAPI_ProjectPointOnSurf proj1(P1,gPlane);
    P1 = proj1.NearestPoint();
    GeomAPI_ProjectPointOnSurf proj2(P2,gPlane);
    P2 = proj2.NearestPoint();

    Base::Vector3d p1(P1.X(),P1.Y(),P1.Z());
    Base::Vector3d p2(P2.X(),P2.Y(),P2.Z());
    invPlm.multVec(p1,p1);
    invPlm.multVec(p2,p2);

    if (Base::Distance(p1,p2) < Precision::Confusion()) {
        Base::Vector3d p = (p1 + p2) / 2;
        Part::GeomPoint* point = new Part::GeomPoint(p);
        GeometryFacade::setConstruction(point, true);
        return point;
    }
    else {
        Part::GeomLineSegment* line = new Part::GeomLineSegment();
        line->setPoints(p1,p2);
        GeometryFacade::setConstruction(line, true);
        return line;
    }
}

bool SketchObject::evaluateSupport()
{
    // returns false if the shape is broken, null or non-planar
    App::DocumentObject *link = Support.getValue();
    if (!link || !link->getTypeId().isDerivedFrom(Part::Feature::getClassTypeId()))
        return false;
    return true;
}

void SketchObject::validateExternalLinks()
{
    Base::StateLocker lock(managedoperation, true); // no need to check input data validity as this is an sketchobject managed operation.

    std::vector<DocumentObject*> Objects     = ExternalGeometry.getValues();
    std::vector<std::string>     SubElements = ExternalGeometry.getSubValues();

    bool rebuild = false;

    for (int i=0; i < int(Objects.size()); i++) {
        const App::DocumentObject *Obj=Objects[i];
        const std::string SubElement=SubElements[i];

        TopoDS_Shape refSubShape;
        try {
            if (Obj->getTypeId().isDerivedFrom(Part::Datum::getClassTypeId())) {
                const Part::Datum* datum = static_cast<const Part::Datum*>(Obj);
                refSubShape = datum->getShape();
            }
            else {
                const Part::Feature *refObj=static_cast<const Part::Feature*>(Obj);
                const Part::TopoShape& refShape=refObj->Shape.getShape();
                refSubShape = refShape.getSubShape(SubElement.c_str());
            }
        }
        catch (Standard_Failure&) {
            rebuild = true ;
            Objects.erase(Objects.begin()+i);
            SubElements.erase(SubElements.begin()+i);

            const std::vector< Constraint * > &constraints = Constraints.getValues();
            std::vector< Constraint * > newConstraints(0);
            int GeoId = GeoEnum::RefExt - i;
            for (std::vector<Constraint *>::const_iterator it = constraints.begin();
                 it != constraints.end(); ++it) {
                if ((*it)->First != GeoId && (*it)->Second != GeoId && (*it)->Third != GeoId) {
                    Constraint *copiedConstr = (*it)->clone();
                    if (copiedConstr->First < GeoId &&
                        copiedConstr->First != GeoEnum::GeoUndef)
                        copiedConstr->First += 1;
                    if (copiedConstr->Second < GeoId &&
                        copiedConstr->Second != GeoEnum::GeoUndef)
                        copiedConstr->Second += 1;
                    if (copiedConstr->Third < GeoId &&
                        copiedConstr->Third != GeoEnum::GeoUndef)
                        copiedConstr->Third += 1;

                    newConstraints.push_back(copiedConstr);
                }
            }

            Constraints.setValues(std::move(newConstraints));
            i--; // we deleted an item, so the next one took its place
        }
    }

    if (rebuild) {
        ExternalGeometry.setValues(Objects,SubElements);
        rebuildExternalGeometry();
        acceptGeometry(); // This may need to be refactor to OnChanged for ExternalGeo
        solve(true); // we have to update this sketch and everything depending on it.
    }
}

void SketchObject::rebuildExternalGeometry()
{
    // get the actual lists of the externals
    std::vector<DocumentObject*> Objects     = ExternalGeometry.getValues();
    std::vector<std::string>     SubElements = ExternalGeometry.getSubValues();

    Base::Placement Plm = Placement.getValue();
    Base::Vector3d Pos = Plm.getPosition();
    Base::Rotation Rot = Plm.getRotation();
    Base::Rotation invRot = Rot.inverse();
    Base::Vector3d dN(0,0,1);
    Rot.multVec(dN,dN);
    Base::Vector3d dX(1,0,0);
    Rot.multVec(dX,dX);

    Base::Placement invPlm = Plm.inverse();
    Base::Matrix4D invMat = invPlm.toMatrix();
    gp_Trsf mov;
    mov.SetValues(invMat[0][0],invMat[0][1],invMat[0][2],invMat[0][3],
                  invMat[1][0],invMat[1][1],invMat[1][2],invMat[1][3],
                  invMat[2][0],invMat[2][1],invMat[2][2],invMat[2][3]);

    gp_Ax3 sketchAx3(gp_Pnt(Pos.x,Pos.y,Pos.z),
                     gp_Dir(dN.x,dN.y,dN.z),
                     gp_Dir(dX.x,dX.y,dX.z));
    gp_Pln sketchPlane(sketchAx3);

    Handle(Geom_Plane) gPlane = new Geom_Plane(sketchPlane);
    BRepBuilderAPI_MakeFace mkFace(sketchPlane);
    TopoDS_Shape aProjFace = mkFace.Shape();

    for (std::vector<Part::Geometry *>::iterator it=ExternalGeo.begin(); it != ExternalGeo.end(); ++it)
        if (*it) delete *it;
    ExternalGeo.clear();
    Part::GeomLineSegment *HLine = new Part::GeomLineSegment();
    Part::GeomLineSegment *VLine = new Part::GeomLineSegment();
    HLine->setPoints(Base::Vector3d(0,0,0),Base::Vector3d(1,0,0));
    VLine->setPoints(Base::Vector3d(0,0,0),Base::Vector3d(0,1,0));
    GeometryFacade::setConstruction(HLine, true);
    GeometryFacade::setConstruction(VLine, true);
    ExternalGeo.push_back(HLine);
    ExternalGeo.push_back(VLine);
    for (int i=0; i < int(Objects.size()); i++) {
        const App::DocumentObject *Obj=Objects[i];
        const std::string SubElement=SubElements[i];

        TopoDS_Shape refSubShape;

        if (Obj->getTypeId().isDerivedFrom(Part::Datum::getClassTypeId())) {
            const Part::Datum* datum = static_cast<const Part::Datum*>(Obj);
            refSubShape = datum->getShape();
        } else if (Obj->getTypeId().isDerivedFrom(Part::Feature::getClassTypeId())) {
            try {
                const Part::Feature *refObj=static_cast<const Part::Feature*>(Obj);
                const Part::TopoShape& refShape=refObj->Shape.getShape();
                refSubShape = refShape.getSubShape(SubElement.c_str());
            }
            catch (Standard_Failure& e) {
                throw Base::CADKernelError(e.GetMessageString());
            }
        } else  if (Obj->getTypeId().isDerivedFrom(App::Plane::getClassTypeId())) {
            const App::Plane* pl = static_cast<const App::Plane*>(Obj);
            Base::Placement plm = pl->Placement.getValue();
            Base::Vector3d base = plm.getPosition();
            Base::Rotation rot = plm.getRotation();
            Base::Vector3d normal(0,0,1);
            rot.multVec(normal, normal);
            gp_Pln plane(gp_Pnt(base.x,base.y,base.z), gp_Dir(normal.x, normal.y, normal.z));
            BRepBuilderAPI_MakeFace fBuilder(plane);
            if (!fBuilder.IsDone())
                throw Base::RuntimeError("Sketcher: addExternal(): Failed to build face from App::Plane");

            TopoDS_Face f = TopoDS::Face(fBuilder.Shape());
            refSubShape = f;
        } else {
            throw Base::TypeError("Datum feature type is not yet supported as external geometry for a sketch");
        }

        switch (refSubShape.ShapeType())
        {
        case TopAbs_FACE:
            {
                const TopoDS_Face& face = TopoDS::Face(refSubShape);
                BRepAdaptor_Surface surface(face);
                if (surface.GetType() == GeomAbs_Plane) {
                    // Check that the plane is perpendicular to the sketch plane
                    Geom_Plane plane = surface.Plane();
                    gp_Dir dnormal = plane.Axis().Direction();
                    gp_Dir snormal = sketchPlane.Axis().Direction();
                    if (fabs(dnormal.Angle(snormal) - M_PI_2) < Precision::Confusion()) {
                        // Get vector that is normal to both sketch plane normal and plane normal. This is the line's direction
                        gp_Dir lnormal = dnormal.Crossed(snormal);
                        BRepBuilderAPI_MakeEdge builder(gp_Lin(plane.Location(), lnormal));
                        builder.Build();
                        if (builder.IsDone()) {
                            const TopoDS_Edge& edge = TopoDS::Edge(builder.Shape());
                            BRepAdaptor_Curve curve(edge);
                            if (curve.GetType() == GeomAbs_Line) {
                                ExternalGeo.push_back(projectLine(curve, gPlane, invPlm));
                            }
                        }

                    } else {
                        throw Base::ValueError("Selected external reference plane must be normal to sketch plane");
                    }
                } else {
                    throw Base::ValueError("Non-planar faces are not yet supported for external geometry of sketches");
                }
            }
            break;
        case TopAbs_EDGE:
            {
                const TopoDS_Edge& edge = TopoDS::Edge(refSubShape);
                BRepAdaptor_Curve curve(edge);
                if (curve.GetType() == GeomAbs_Line) {
                    ExternalGeo.push_back(projectLine(curve, gPlane, invPlm));
                }
                else if (curve.GetType() == GeomAbs_Circle) {
                    gp_Dir vec1 = sketchPlane.Axis().Direction();
                    gp_Dir vec2 = curve.Circle().Axis().Direction();
                    if (vec1.IsParallel(vec2, Precision::Confusion())) {
                        gp_Circ circle = curve.Circle();
                        gp_Pnt cnt = circle.Location();
                        gp_Pnt beg = curve.Value(curve.FirstParameter());
                        gp_Pnt end = curve.Value(curve.LastParameter());

                        GeomAPI_ProjectPointOnSurf proj(cnt,gPlane);
                        cnt = proj.NearestPoint();
                        circle.SetLocation(cnt);
                        cnt.Transform(mov);
                        circle.Transform(mov);

                        if (beg.SquareDistance(end) < Precision::Confusion()) {
                            Part::GeomCircle* gCircle = new Part::GeomCircle();
                            gCircle->setRadius(circle.Radius());
                            gCircle->setCenter(Base::Vector3d(cnt.X(),cnt.Y(),cnt.Z()));

                            GeometryFacade::setConstruction(gCircle, true);
                            ExternalGeo.push_back(gCircle);
                        }
                        else {
                            Part::GeomArcOfCircle* gArc = new Part::GeomArcOfCircle();
                            Handle(Geom_Curve) hCircle = new Geom_Circle(circle);
                            Handle(Geom_TrimmedCurve) tCurve = new Geom_TrimmedCurve(hCircle, curve.FirstParameter(),
                                                                                    curve.LastParameter());
                            gArc->setHandle(tCurve);
                            GeometryFacade::setConstruction(gArc, true);
                            ExternalGeo.push_back(gArc);
                        }
                    }
                    else {
                        // creates an ellipse or a segment

                        gp_Dir vec1 = sketchPlane.Axis().Direction();
                        gp_Dir vec2 = curve.Circle().Axis().Direction();
                        gp_Circ origCircle = curve.Circle();

                        if (vec1.IsNormal(vec2, Precision::Angular())) {  // circle's normal vector in plane:
                            //   projection is a line
                            //   define center by projection
                            gp_Pnt cnt = origCircle.Location();
                            GeomAPI_ProjectPointOnSurf proj(cnt,gPlane);
                            cnt = proj.NearestPoint();

                            gp_Dir dirOrientation = gp_Dir(vec1 ^ vec2);
                            gp_Dir dirLine(dirOrientation);

                            Part::GeomLineSegment * projectedSegment = new Part::GeomLineSegment();
                            Geom_Line ligne(cnt, dirLine);  // helper object to compute end points
                            gp_Pnt P1, P2;  // end points of the segment, OCC style

                            ligne.D0(-origCircle.Radius(), P1);
                            ligne.D0( origCircle.Radius(), P2);

                            if (!curve.IsClosed()) {  // arc of circle

                                gp_Pnt pntF = curve.Value(curve.FirstParameter());  // start point of arc of circle
                                gp_Pnt pntL = curve.Value(curve.LastParameter());  // end point of arc of circle

                                double alpha = dirOrientation.AngleWithRef(curve.Circle().XAxis().Direction(), curve.Circle().Axis().Direction());

                                double baseAngle = curve.FirstParameter();

                                int tours = 0;
                                double startAngle = baseAngle + alpha;
                                // bring startAngle back in [-pi/2 , 3pi/2[
                                while(startAngle < -M_PI/2.0 && tours < 10) {
                                    startAngle = baseAngle + ++tours*2.0*M_PI + alpha;
                                }
                                while(startAngle >= 3.0*M_PI/2.0 && tours > -10) {
                                    startAngle = baseAngle + --tours*2.0*M_PI + alpha;
                                }

                                double endAngle = curve.LastParameter() + startAngle - baseAngle;  // apply same offset to end angle

                                if (startAngle <= 0.0) {
                                    if (endAngle <= 0.0) {
                                        P1 = ProjPointOnPlane_XYZ(pntF, sketchPlane);
                                        P2 = ProjPointOnPlane_XYZ(pntL, sketchPlane);
                                    } else {
                                        if (endAngle <= fabs(startAngle)) {
                                            // P2 = P2 already defined
                                            P1 = ProjPointOnPlane_XYZ(pntF, sketchPlane);
                                        } else if (endAngle < M_PI) {
                                            // P2 = P2, already defined
                                            P1 = ProjPointOnPlane_XYZ(pntL, sketchPlane);
                                        } else {
                                            // P1 = P1, already defined
                                            // P2 = P2, already defined
                                        }
                                    }
                                } else if (startAngle < M_PI) {
                                    if (endAngle < M_PI) {
                                        P1 = ProjPointOnPlane_XYZ(pntF, sketchPlane);
                                        P2 = ProjPointOnPlane_XYZ(pntL, sketchPlane);
                                    } else if (endAngle < 2.0 * M_PI - startAngle) {
                                        P2 = ProjPointOnPlane_XYZ(pntF, sketchPlane);
                                        // P1 = P1, already defined
                                    } else if (endAngle < 2.0 * M_PI) {
                                        P2 = ProjPointOnPlane_XYZ(pntL, sketchPlane);
                                        // P1 = P1, already defined
                                    } else {
                                        // P1 = P1, already defined
                                        // P2 = P2, already defined
                                    }
                                } else {
                                    if (endAngle < 2*M_PI) {
                                        P1 = ProjPointOnPlane_XYZ(pntF, sketchPlane);
                                        P2 = ProjPointOnPlane_XYZ(pntL, sketchPlane);
                                    } else if (endAngle < 4*M_PI - startAngle) {
                                        P1 = ProjPointOnPlane_XYZ(pntF, sketchPlane);
                                        // P2 = P2, already defined
                                    } else if (endAngle < 3*M_PI) {
                                        // P1 = P1, already defined
                                        P2 = ProjPointOnPlane_XYZ(pntL, sketchPlane);
                                    } else {
                                        // P1 = P1, already defined
                                        // P2 = P2, already defined
                                    }
                                }
                            }

                            Base::Vector3d p1(P1.X(),P1.Y(),P1.Z());  // ends of segment FCAD style
                            Base::Vector3d p2(P2.X(),P2.Y(),P2.Z());
                            invPlm.multVec(p1,p1);
                            invPlm.multVec(p2,p2);

                            projectedSegment->setPoints(p1, p2);
                            GeometryFacade::setConstruction(projectedSegment, true);
                            ExternalGeo.push_back(projectedSegment);
                        }
                        else {  // general case, full circle
                            gp_Pnt cnt = origCircle.Location();
                            GeomAPI_ProjectPointOnSurf proj(cnt,gPlane);
                            cnt = proj.NearestPoint();  // projection of circle center on sketch plane, 3D space
                            Base::Vector3d p(cnt.X(),cnt.Y(),cnt.Z());  // converting to FCAD style vector
                            invPlm.multVec(p,p);  // transforming towards sketch's (x,y) coordinates


                            gp_Vec vecMajorAxis = vec1 ^ vec2;  // major axis in 3D space

                            double minorRadius;  // TODO use data type of vectors around...
                            double cosTheta;
                            cosTheta = fabs(vec1.Dot(vec2));  // cos of angle between the two planes, assuming vectirs are normalized to 1
                            minorRadius = origCircle.Radius() * cosTheta;

                            Base::Vector3d vectorMajorAxis(vecMajorAxis.X(),vecMajorAxis.Y(),vecMajorAxis.Z());  // maj axis into FCAD style vector
                            invRot.multVec(vectorMajorAxis, vectorMajorAxis);  // transforming to sketch's (x,y) coordinates
                            vecMajorAxis.SetXYZ(gp_XYZ(vectorMajorAxis[0], vectorMajorAxis[1], vectorMajorAxis[2]));  // back to OCC

                            gp_Ax2 refFrameEllipse(gp_Pnt(gp_XYZ(p[0], p[1], p[2])), gp_Vec(0, 0, 1), vecMajorAxis);  // NB: force normal of ellipse to be normal of sketch's plane.
                            Handle(Geom_Ellipse) curve = new Geom_Ellipse(refFrameEllipse, origCircle.Radius(), minorRadius);
                            Part::GeomEllipse* ellipse = new Part::GeomEllipse();
                            ellipse->setHandle(curve);
                            GeometryFacade::setConstruction(ellipse, true);

                            ExternalGeo.push_back(ellipse);
                        }
                    }
                }
                else if (curve.GetType() == GeomAbs_Ellipse) {

                    gp_Elips elipsOrig = curve.Ellipse();
                    gp_Elips elipsDest;
                    gp_Pnt origCenter = elipsOrig.Location();
                    gp_Pnt destCenter = ProjPointOnPlane_UVN(origCenter, sketchPlane).XYZ();

                    gp_Dir origAxisMajorDir = elipsOrig.XAxis().Direction();
                    gp_Vec origAxisMajor = elipsOrig.MajorRadius() * gp_Vec(origAxisMajorDir);
                    gp_Dir origAxisMinorDir = elipsOrig.YAxis().Direction();
                    gp_Vec origAxisMinor = elipsOrig.MinorRadius() * gp_Vec(origAxisMinorDir);

                    // Here, it used to be a test for parallel direction between the sketchplane and the elipsOrig, in which
                    // the original ellipse would be copied and translated to the new position.
                    // The problem with that approach is that for the sketcher the normal vector is always (0,0,1). If the original
                    // ellipse was not on the XY plane, the copy will not be either. Then, the dimensions would be wrong because of the
                    // different major axis direction (which is not projected on the XY plane). So here, we default to the more general
                    // ellipse construction algorithm.
                    //
                    // Doing that solves:
                    // https://forum.freecadweb.org/viewtopic.php?f=3&t=55284#p477522

                    // GENERAL ELLIPSE CONSTRUCTION ALGORITHM
                    //
                    // look for major axis of projected ellipse
                    //
                    // t is the parameter along the origin ellipse
                    //   OM(t) = origCenter
                    //           + majorRadius * cos(t) * origAxisMajorDir
                    //           + minorRadius * sin(t) * origAxisMinorDir
                    gp_Vec2d PA = ProjVecOnPlane_UV(origAxisMajor, sketchPlane);
                    gp_Vec2d PB = ProjVecOnPlane_UV(origAxisMinor, sketchPlane);
                    double t_max = 2.0 * PA.Dot(PB) / (PA.SquareMagnitude() - PB.SquareMagnitude());
                    t_max = 0.5 * atan(t_max);  // gives new major axis is most cases, but not all
                    double t_min = t_max + 0.5 * M_PI;

                    // ON_max = OM(t_max) gives the point, which projected on the sketch plane,
                    //     becomes the apoapse of the pojected ellipse.
                    gp_Vec ON_max = origAxisMajor * cos(t_max) + origAxisMinor * sin(t_max);
                    gp_Vec ON_min = origAxisMajor * cos(t_min) + origAxisMinor * sin(t_min);
                    gp_Vec destAxisMajor = ProjVecOnPlane_UVN(ON_max, sketchPlane);
                    gp_Vec destAxisMinor = ProjVecOnPlane_UVN(ON_min, sketchPlane);

                    double RDest = destAxisMajor.Magnitude();
                    double rDest = destAxisMinor.Magnitude();

                    if (RDest < rDest) {
                        double rTmp = rDest;
                        rDest = RDest;
                        RDest = rTmp;
                        gp_Vec axisTmp = destAxisMajor;
                        destAxisMajor = destAxisMinor;
                        destAxisMinor = axisTmp;
                    }

                    double sens = sketchAx3.Direction().Dot(elipsOrig.Position().Direction());
                    gp_Ax2 destCurveAx2(destCenter,
                            gp_Dir(0, 0, sens > 0.0 ? 1.0 : -1.0),
                            gp_Dir(destAxisMajor));

                    if ((RDest - rDest) < (double) Precision::Confusion()) {  // projection is a circle
                        Handle(Geom_Circle) curve = new Geom_Circle(destCurveAx2, 0.5 * (rDest + RDest));
                        Part::GeomCircle* circle = new Part::GeomCircle();
                        circle->setHandle(curve);
                        GeometryFacade::setConstruction(circle, true);

                        ExternalGeo.push_back(circle);
                    }
                    else {
                        if (sketchPlane.Position().Direction().IsNormal(elipsOrig.Position().Direction(), Precision::Angular())) {
                            gp_Vec start = gp_Vec(destCenter.XYZ()) + destAxisMajor;
                            gp_Vec end = gp_Vec(destCenter.XYZ()) - destAxisMajor;

                            Part::GeomLineSegment * projectedSegment = new Part::GeomLineSegment();
                            projectedSegment->setPoints(Base::Vector3d(start.X(), start.Y(), start.Z()),
                                                        Base::Vector3d(end.X(), end.Y(), end.Z()));
                            GeometryFacade::setConstruction(projectedSegment, true);
                            ExternalGeo.push_back(projectedSegment);
                        }
                        else {

                            elipsDest.SetPosition(destCurveAx2);
                            elipsDest.SetMajorRadius(destAxisMajor.Magnitude());
                            elipsDest.SetMinorRadius(destAxisMinor.Magnitude());


                            Handle(Geom_Ellipse) curve = new Geom_Ellipse(elipsDest);
                            Part::GeomEllipse* ellipse = new Part::GeomEllipse();
                            ellipse->setHandle(curve);
                            GeometryFacade::setConstruction(ellipse, true);

                            ExternalGeo.push_back(ellipse);
                        }
                    }
                }
                else {
                    try {
                        BRepOffsetAPI_NormalProjection mkProj(aProjFace);
                        mkProj.Add(edge);
                        mkProj.Build();
                        const TopoDS_Shape& projShape = mkProj.Projection();
                        if (!projShape.IsNull()) {
                            TopExp_Explorer xp;
                            for (xp.Init(projShape, TopAbs_EDGE); xp.More(); xp.Next()) {
                                TopoDS_Edge projEdge = TopoDS::Edge(xp.Current());
                                TopLoc_Location loc(mov);
                                projEdge.Location(loc);
                                BRepAdaptor_Curve projCurve(projEdge);
                                if (projCurve.GetType() == GeomAbs_Line) {
                                    gp_Pnt P1 = projCurve.Value(projCurve.FirstParameter());
                                    gp_Pnt P2 = projCurve.Value(projCurve.LastParameter());
                                    Base::Vector3d p1(P1.X(),P1.Y(),P1.Z());
                                    Base::Vector3d p2(P2.X(),P2.Y(),P2.Z());

                                    if (Base::Distance(p1,p2) < Precision::Confusion()) {
                                        Base::Vector3d p = (p1 + p2) / 2;
                                        Part::GeomPoint* point = new Part::GeomPoint(p);
                                        GeometryFacade::setConstruction(point, true);
                                        ExternalGeo.push_back(point);
                                    }
                                    else {
                                        Part::GeomLineSegment* line = new Part::GeomLineSegment();
                                        line->setPoints(p1,p2);
                                        GeometryFacade::setConstruction(line, true);
                                        ExternalGeo.push_back(line);
                                    }
                                }
                                else if (projCurve.GetType() == GeomAbs_Circle) {
                                    gp_Circ c = projCurve.Circle();
                                    gp_Pnt p = c.Location();
                                    gp_Pnt P1 = projCurve.Value(projCurve.FirstParameter());
                                    gp_Pnt P2 = projCurve.Value(projCurve.LastParameter());

                                    if (P1.SquareDistance(P2) < Precision::Confusion()) {
                                        Part::GeomCircle* circle = new Part::GeomCircle();
                                        circle->setRadius(c.Radius());
                                        circle->setCenter(Base::Vector3d(p.X(),p.Y(),p.Z()));

                                        GeometryFacade::setConstruction(circle, true);
                                        ExternalGeo.push_back(circle);
                                    }
                                    else {
                                        Part::GeomArcOfCircle* arc = new Part::GeomArcOfCircle();
                                        Handle(Geom_Curve) curve = new Geom_Circle(c);
                                        Handle(Geom_TrimmedCurve) tCurve = new Geom_TrimmedCurve(curve, projCurve.FirstParameter(),
                                                                                                projCurve.LastParameter());
                                        arc->setHandle(tCurve);
                                        GeometryFacade::setConstruction(arc, true);
                                        ExternalGeo.push_back(arc);
                                    }
                                } else if (projCurve.GetType() == GeomAbs_BSplineCurve) {
                                    // Unfortunately, a normal projection of a circle can also give a Bspline
                                    // Split the spline into arcs
                                    GeomConvert_BSplineCurveKnotSplitting bSplineSplitter(projCurve.BSpline(), 2);
                                    //int s = bSplineSplitter.NbSplits();
                                    if ((curve.GetType() == GeomAbs_Circle) && (bSplineSplitter.NbSplits() == 2)) {
                                        // Result of projection is actually a circle...
                                        TColStd_Array1OfInteger splits(1, 2);
                                        bSplineSplitter.Splitting(splits);
                                        gp_Pnt p1 = projCurve.Value(splits(1));
                                        gp_Pnt p2 = projCurve.Value(splits(2));
                                        gp_Pnt p3 = projCurve.Value(0.5 * (splits(1) + splits(2)));
                                        GC_MakeCircle circleMaker(p1, p2, p3);
                                        Handle(Geom_Circle) circ = circleMaker.Value();
                                        Part::GeomCircle* circle = new Part::GeomCircle();
                                        circle->setRadius(circ->Radius());
                                        gp_Pnt center = circ->Axis().Location();
                                        circle->setCenter(Base::Vector3d(center.X(), center.Y(), center.Z()));

                                        GeometryFacade::setConstruction(circle, true);
                                        ExternalGeo.push_back(circle);
                                    } else {
                                        Part::GeomBSplineCurve* bspline = new Part::GeomBSplineCurve(projCurve.BSpline());
                                        GeometryFacade::setConstruction(bspline, true);
                                        ExternalGeo.push_back(bspline);
                                    }
                                } else if (projCurve.GetType() == GeomAbs_Hyperbola) {
                                    gp_Hypr e = projCurve.Hyperbola();
                                    gp_Pnt p = e.Location();
                                    gp_Pnt P1 = projCurve.Value(projCurve.FirstParameter());
                                    gp_Pnt P2 = projCurve.Value(projCurve.LastParameter());

                                    gp_Dir normal = e.Axis().Direction();
                                    gp_Dir xdir = e.XAxis().Direction();
                                    gp_Ax2 xdirref(p, normal);

                                    if (P1.SquareDistance(P2) < Precision::Confusion()) {
                                        Part::GeomHyperbola* hyperbola = new Part::GeomHyperbola();
                                        hyperbola->setMajorRadius(e.MajorRadius());
                                        hyperbola->setMinorRadius(e.MinorRadius());
                                        hyperbola->setCenter(Base::Vector3d(p.X(),p.Y(),p.Z()));
                                        hyperbola->setAngleXU(-xdir.AngleWithRef(xdirref.XDirection(),normal));
                                        GeometryFacade::setConstruction(hyperbola, true);
                                        ExternalGeo.push_back(hyperbola);
                                    }
                                    else {
                                        Part::GeomArcOfHyperbola* aoh = new Part::GeomArcOfHyperbola();
                                        Handle(Geom_Curve) curve = new Geom_Hyperbola(e);
                                        Handle(Geom_TrimmedCurve) tCurve = new Geom_TrimmedCurve(curve, projCurve.FirstParameter(),
                                                                                                projCurve.LastParameter());
                                        aoh->setHandle(tCurve);
                                        GeometryFacade::setConstruction(aoh, true);
                                        ExternalGeo.push_back(aoh);
                                    }
                                } else if (projCurve.GetType() == GeomAbs_Parabola) {
                                    gp_Parab e = projCurve.Parabola();
                                    gp_Pnt p = e.Location();
                                    gp_Pnt P1 = projCurve.Value(projCurve.FirstParameter());
                                    gp_Pnt P2 = projCurve.Value(projCurve.LastParameter());

                                    gp_Dir normal = e.Axis().Direction();
                                    gp_Dir xdir = e.XAxis().Direction();
                                    gp_Ax2 xdirref(p, normal);

                                    if (P1.SquareDistance(P2) < Precision::Confusion()) {
                                        Part::GeomParabola* parabola = new Part::GeomParabola();
                                        parabola->setFocal(e.Focal());
                                        parabola->setCenter(Base::Vector3d(p.X(),p.Y(),p.Z()));
                                        parabola->setAngleXU(-xdir.AngleWithRef(xdirref.XDirection(),normal));
                                        GeometryFacade::setConstruction(parabola, true);
                                        ExternalGeo.push_back(parabola);
                                    }
                                    else {
                                        Part::GeomArcOfParabola* aop = new Part::GeomArcOfParabola();
                                        Handle(Geom_Curve) curve = new Geom_Parabola(e);
                                        Handle(Geom_TrimmedCurve) tCurve = new Geom_TrimmedCurve(curve, projCurve.FirstParameter(),
                                                                                                projCurve.LastParameter());
                                        aop->setHandle(tCurve);
                                        GeometryFacade::setConstruction(aop, true);
                                        ExternalGeo.push_back(aop);
                                    }
                                }
                                else if (projCurve.GetType() == GeomAbs_Ellipse) {
                                    gp_Elips e = projCurve.Ellipse();
                                    gp_Pnt p = e.Location();
                                    gp_Pnt P1 = projCurve.Value(projCurve.FirstParameter());
                                    gp_Pnt P2 = projCurve.Value(projCurve.LastParameter());

                                    //gp_Dir normal = e.Axis().Direction();
                                    gp_Dir normal = gp_Dir(0,0,1);
                                    gp_Ax2 xdirref(p, normal);

                                    if (P1.SquareDistance(P2) < Precision::Confusion()) {
                                        Part::GeomEllipse* ellipse = new Part::GeomEllipse();
                                        Handle(Geom_Ellipse) curve = new Geom_Ellipse(e);
                                        ellipse->setHandle(curve);
                                        GeometryFacade::setConstruction(ellipse, true);
                                        ExternalGeo.push_back(ellipse);
                                    }
                                    else {
                                        Part::GeomArcOfEllipse* aoe = new Part::GeomArcOfEllipse();
                                        Handle(Geom_Curve) curve = new Geom_Ellipse(e);
                                        Handle(Geom_TrimmedCurve) tCurve = new Geom_TrimmedCurve(curve, projCurve.FirstParameter(),
                                                                                                projCurve.LastParameter());
                                        aoe->setHandle(tCurve);
                                        GeometryFacade::setConstruction(aoe, true);
                                        ExternalGeo.push_back(aoe);
                                    }
                                }
                                else {
                                    throw Base::NotImplementedError("Not yet supported geometry for external geometry");
                                }
                            }
                        }
                    }
                    catch (Standard_Failure& e) {
                        throw Base::CADKernelError(e.GetMessageString());
                    }
                }
            }
            break;
        case TopAbs_VERTEX:
            {
                gp_Pnt P = BRep_Tool::Pnt(TopoDS::Vertex(refSubShape));
                GeomAPI_ProjectPointOnSurf proj(P,gPlane);
                P = proj.NearestPoint();
                Base::Vector3d p(P.X(),P.Y(),P.Z());
                invPlm.multVec(p,p);

                Part::GeomPoint* point = new Part::GeomPoint(p);
                GeometryFacade::setConstruction(point, true);
                ExternalGeo.push_back(point);
            }
            break;
        default:
            throw Base::TypeError("Unknown type of geometry");
            break;
        }
    }

    rebuildVertexIndex();
}

std::vector<Part::Geometry*> SketchObject::getCompleteGeometry() const
{
    std::vector<Part::Geometry*> vals = getInternalGeometry();
    vals.insert(vals.end(), ExternalGeo.rbegin(), ExternalGeo.rend()); // in reverse order
    return vals;
}

GeoListFacade SketchObject::getGeoListFacade() const
{
    std::vector<GeometryFacadeUniquePtr> facade;
    facade.reserve( Geometry.getSize() + ExternalGeo.size() );

    for(auto geo : Geometry.getValues())
        facade.push_back(GeometryFacade::getFacade(geo));

    for(auto rit = ExternalGeo.rbegin(); rit != ExternalGeo.rend(); rit++)
        facade.push_back(GeometryFacade::getFacade(*rit));

    return GeoListFacade::getGeoListModel(std::move(facade), Geometry.getSize());
}

void SketchObject::rebuildVertexIndex()
{
    VertexId2GeoId.resize(0);
    VertexId2PosId.resize(0);
    int imax=getHighestCurveIndex();
    int i=0;
    const std::vector< Part::Geometry * > geometry = getCompleteGeometry();
    if (geometry.size() <= 2)
        return;
    for (std::vector< Part::Geometry * >::const_iterator it = geometry.begin();
         it != geometry.end()-2; ++it, i++) {
        if (i > imax)
              i = -getExternalGeometryCount();
        if ((*it)->getTypeId() == Part::GeomPoint::getClassTypeId()) {
            VertexId2GeoId.push_back(i);
            VertexId2PosId.push_back(PointPos::start);
        } else if ((*it)->getTypeId() == Part::GeomLineSegment::getClassTypeId()) {
            VertexId2GeoId.push_back(i);
            VertexId2PosId.push_back(PointPos::start);
            VertexId2GeoId.push_back(i);
            VertexId2PosId.push_back(PointPos::end);
        } else if ((*it)->getTypeId() == Part::GeomCircle::getClassTypeId()) {
            VertexId2GeoId.push_back(i);
            VertexId2PosId.push_back(PointPos::mid);
        } else if ((*it)->getTypeId() == Part::GeomEllipse::getClassTypeId()) {
            VertexId2GeoId.push_back(i);
            VertexId2PosId.push_back(PointPos::mid);
        } else if ((*it)->getTypeId() == Part::GeomArcOfCircle::getClassTypeId()) {
            VertexId2GeoId.push_back(i);
            VertexId2PosId.push_back(PointPos::start);
            VertexId2GeoId.push_back(i);
            VertexId2PosId.push_back(PointPos::end);
            VertexId2GeoId.push_back(i);
            VertexId2PosId.push_back(PointPos::mid);
        } else if ((*it)->getTypeId() == Part::GeomArcOfEllipse::getClassTypeId()) {
            VertexId2GeoId.push_back(i);
            VertexId2PosId.push_back(PointPos::start);
            VertexId2GeoId.push_back(i);
            VertexId2PosId.push_back(PointPos::end);
            VertexId2GeoId.push_back(i);
            VertexId2PosId.push_back(PointPos::mid);
        } else if ((*it)->getTypeId() == Part::GeomArcOfHyperbola::getClassTypeId()) {
            VertexId2GeoId.push_back(i);
            VertexId2PosId.push_back(PointPos::start);
            VertexId2GeoId.push_back(i);
            VertexId2PosId.push_back(PointPos::end);
            VertexId2GeoId.push_back(i);
            VertexId2PosId.push_back(PointPos::mid);
        } else if ((*it)->getTypeId() == Part::GeomArcOfParabola::getClassTypeId()) {
            VertexId2GeoId.push_back(i);
            VertexId2PosId.push_back(PointPos::start);
            VertexId2GeoId.push_back(i);
            VertexId2PosId.push_back(PointPos::end);
            VertexId2GeoId.push_back(i);
            VertexId2PosId.push_back(PointPos::mid);
        } else if ((*it)->getTypeId() == Part::GeomBSplineCurve::getClassTypeId()) {
            VertexId2GeoId.push_back(i);
            VertexId2PosId.push_back(PointPos::start);
            VertexId2GeoId.push_back(i);
            VertexId2PosId.push_back(PointPos::end);
        }
    }
}

const std::vector< std::map<int, Sketcher::PointPos> > SketchObject::getCoincidenceGroups()
{
    // this function is different from that in getCoincidentPoints in that:
    // - getCoincidentPoints only considers direct coincidence (the points that are linked via a single coincidence)
    // - this function provides an array of maps of points, each map containing the points that are coincident by virtue
    //   of any number of interrelated coincidence constraints (if coincidence 1-2 and coincidence 2-3, {1,2,3} are in that set)

    const std::vector< Sketcher::Constraint * > &vals = Constraints.getValues();

    std::vector< std::map<int, Sketcher::PointPos> > coincidenttree;
    // push the constraints
    for (std::vector< Sketcher::Constraint * >::const_iterator it= vals.begin();it != vals.end(); ++it) {
        if( (*it)->Type == Sketcher::Coincident ) {
            int firstpresentin=-1;
            int secondpresentin=-1;

            int i=0;

            for(std::vector< std::map<int, Sketcher::PointPos> >::const_iterator iti = coincidenttree.begin(); iti != coincidenttree.end(); ++iti,i++) {
                // First
                std::map<int, Sketcher::PointPos>::const_iterator filiterator;
                filiterator = (*iti).find((*it)->First);
                if( filiterator != (*iti).end()) {
                    if((*it)->FirstPos == (*filiterator).second)
                        firstpresentin = i;
                }
                // Second
                filiterator = (*iti).find((*it)->Second);
                if( filiterator != (*iti).end()) {
                    if((*it)->SecondPos == (*filiterator).second)
                        secondpresentin = i;
                }
            }

            if ( firstpresentin!=-1 && secondpresentin!=-1) {
                // we have to merge those sets into one
                coincidenttree[firstpresentin].insert(coincidenttree[secondpresentin].begin(), coincidenttree[secondpresentin].end());
                coincidenttree.erase(coincidenttree.begin()+secondpresentin);
            }
            else if ( firstpresentin==-1 && secondpresentin==-1 ) {
                // we do not have any of the values, so create a setCursor
                std::map<int, Sketcher::PointPos> tmp;
                tmp.insert(std::pair<int, Sketcher::PointPos>((*it)->First,(*it)->FirstPos));
                tmp.insert(std::pair<int, Sketcher::PointPos>((*it)->Second,(*it)->SecondPos));
                coincidenttree.push_back(tmp);
            }
            else if ( firstpresentin != -1 ) {
                // add to existing group
                coincidenttree[firstpresentin].insert(std::pair<int, Sketcher::PointPos>((*it)->Second,(*it)->SecondPos));
            }
            else { // secondpresentin != -1
                // add to existing group
                coincidenttree[secondpresentin].insert(std::pair<int, Sketcher::PointPos>((*it)->First,(*it)->FirstPos));
            }

        }
    }

    return coincidenttree;
}

void SketchObject::isCoincidentWithExternalGeometry(int GeoId, bool &start_external, bool &mid_external, bool &end_external) {

    start_external=false;
    mid_external=false;
    end_external=false;

    const std::vector< std::map<int, Sketcher::PointPos> > coincidenttree = getCoincidenceGroups();

    for(std::vector< std::map<int, Sketcher::PointPos> >::const_iterator it = coincidenttree.begin(); it != coincidenttree.end(); ++it) {

        std::map<int, Sketcher::PointPos>::const_iterator geoId1iterator;

        geoId1iterator = (*it).find(GeoId);

        if( geoId1iterator != (*it).end()) {
            // If First is in this set and the first key in this ordered element key is external
            if( (*it).begin()->first < 0 ) {
                if( (*geoId1iterator).second == Sketcher::PointPos::start )
                    start_external=true;
                else if ( (*geoId1iterator).second == Sketcher::PointPos::mid )
                    mid_external=true;
                else if ( (*geoId1iterator).second == Sketcher::PointPos::end )
                    end_external=true;
            }
        }
    }
}

const std::map<int, Sketcher::PointPos> SketchObject::getAllCoincidentPoints(int GeoId, PointPos PosId) {

    const std::vector< std::map<int, Sketcher::PointPos> > coincidenttree = getCoincidenceGroups();

    for(std::vector< std::map<int, Sketcher::PointPos> >::const_iterator it = coincidenttree.begin(); it != coincidenttree.end(); ++it) {

        std::map<int, Sketcher::PointPos>::const_iterator geoId1iterator;

        geoId1iterator = (*it).find(GeoId);

        if( geoId1iterator != (*it).end()) {
            // If GeoId is in this set

            if ((*geoId1iterator).second == PosId) // and posId matches
                return (*it);
        }
    }

    std::map<int, Sketcher::PointPos> empty;

    return empty;
}


void SketchObject::getDirectlyCoincidentPoints(int GeoId, PointPos PosId, std::vector<int> &GeoIdList,
                                       std::vector<PointPos> &PosIdList)
{
    const std::vector<Constraint *> &constraints = this->Constraints.getValues();

    GeoIdList.clear();
    PosIdList.clear();
    GeoIdList.push_back(GeoId);
    PosIdList.push_back(PosId);
    for (std::vector<Constraint *>::const_iterator it=constraints.begin();
         it != constraints.end(); ++it) {
        if ((*it)->Type == Sketcher::Coincident) {
            if ((*it)->First == GeoId && (*it)->FirstPos == PosId) {
                GeoIdList.push_back((*it)->Second);
                PosIdList.push_back((*it)->SecondPos);
            }
            else if ((*it)->Second == GeoId && (*it)->SecondPos == PosId) {
                GeoIdList.push_back((*it)->First);
                PosIdList.push_back((*it)->FirstPos);
            }
        }
    }
    if (GeoIdList.size() == 1) {
        GeoIdList.clear();
        PosIdList.clear();
    }
}

void SketchObject::getDirectlyCoincidentPoints(int VertexId, std::vector<int> &GeoIdList,
                                       std::vector<PointPos> &PosIdList)
{
    int GeoId;
    PointPos PosId;
    getGeoVertexIndex(VertexId, GeoId, PosId);
    getDirectlyCoincidentPoints(GeoId, PosId, GeoIdList, PosIdList);
}

bool SketchObject::arePointsCoincident(int GeoId1, PointPos PosId1,
                                       int GeoId2, PointPos PosId2)
{
    if (GeoId1 == GeoId2 && PosId1 == PosId2)
        return true;

    const std::vector< std::map<int, Sketcher::PointPos> > coincidenttree = getCoincidenceGroups();

    for(std::vector< std::map<int, Sketcher::PointPos> >::const_iterator it = coincidenttree.begin(); it != coincidenttree.end(); ++it) {

        std::map<int, Sketcher::PointPos>::const_iterator geoId1iterator;

        geoId1iterator = (*it).find(GeoId1);

        if( geoId1iterator != (*it).end()) {
            // If First is in this set
            std::map<int, Sketcher::PointPos>::const_iterator geoId2iterator;

            geoId2iterator = (*it).find(GeoId2);

            if( geoId2iterator != (*it).end()) {
                // If Second is in this set
                if ((*geoId1iterator).second == PosId1 &&
                    (*geoId2iterator).second == PosId2)
                    return true;
            }
        }
    }

    return false;
}

void SketchObject::getConstraintIndices (int GeoId, std::vector<int> &constraintList)
{
    const std::vector<Constraint *> &constraints = this->Constraints.getValues();
    int i = 0;

    for (std::vector<Constraint *>::const_iterator it = constraints.begin(); it != constraints.end(); ++it) {
         if ((*it)->First == GeoId || (*it)->Second == GeoId || (*it)->Third == GeoId) {
             constraintList.push_back(i);
         }
         ++i;
    }
}

void SketchObject::appendConflictMsg(const std::vector<int> &conflicting, std::string &msg)
{
    appendConstraintsMsg(conflicting,
                         "Please remove the following conflicting constraint:\n",
                         "Please remove at least one of the following conflicting constraints:\n",
                         msg);
}

void SketchObject::appendRedundantMsg(const std::vector<int> &redundant, std::string &msg)
{
    appendConstraintsMsg(redundant,
                         "Please remove the following redundant constraint:",
                         "Please remove the following redundant constraints:",
                         msg);
}

void SketchObject::appendMalformedConstraintsMsg(const std::vector<int> &malformed, std::string &msg)
{
    appendConstraintsMsg(malformed,
                         "Please remove the following malformed constraint:",
                         "Please remove the following malformed constraints:",
                         msg);
}

void SketchObject::appendConstraintsMsg(const std::vector<int> &vector,
                                        const std::string &singularmsg,
                                        const std::string &pluralmsg,
                                        std::string &msg)
{
    std::stringstream ss;
    if (msg.length() > 0)
        ss << msg;
    if (!vector.empty()) {
        if (vector.size() == 1)
            ss << singularmsg << std::endl;
        else
            ss << pluralmsg;
        ss << vector[0] << std::endl;
        for (unsigned int i=1; i < vector.size(); i++)
            ss << ", " << vector[i];
        ss << "\n";
    }
    msg = ss.str();
}


void SketchObject::getGeometryWithDependentParameters(std::vector<std::pair<int,PointPos>>& geometrymap)
{
    auto geos = getInternalGeometry();

    int geoid = 0;

    for(auto geo : geos) {
        if(geo) {
            if(geo->hasExtension(Sketcher::SolverGeometryExtension::getClassTypeId())) {

                auto solvext = std::static_pointer_cast<const Sketcher::SolverGeometryExtension>(
                                    geo->getExtension(Sketcher::SolverGeometryExtension::getClassTypeId()).lock());

                if (solvext->getGeometry() == Sketcher::SolverGeometryExtension::NotFullyConstraint) {
                    // The solver differentiates whether the parameters that are dependent are not those
                    // of start, end, mid, and assigns them to the edge (edge params = curve params - parms of start, end, mid).
                    // The user looking at the UI expects that the edge of a NotFullyConstraint geometry
                    // will always move, even if the edge parameters are independent, for example if mid is
                    // the only dependent parameter. In other words, the user could reasonably restrict the edge
                    // to reach a fully constrained element. Under this understanding, the edge parameter would
                    // always be dependent, unless the element is fully constrained.
                    //
                    // While this is ok from a user visual expectation point of view, it leads to a loss of information
                    // of whether restricting the point start, end, mid that is dependent may suffice, or even if such
                    // points are restricted, the edge would still need to be restricted.
                    //
                    // Because Python gets the information in this function, it would lead to Python users having access
                    // to a lower amount of detail.
                    //
                    // For this reason, this function returns edge as dependent parameter if and only if constraining the
                    // parameters of the points would not suffice to constraint the element.
                    if (solvext->getEdge() == SolverGeometryExtension::Dependent)
                        geometrymap.emplace_back(geoid,Sketcher::PointPos::none);
                    if (solvext->getStart() == SolverGeometryExtension::Dependent)
                        geometrymap.emplace_back(geoid,Sketcher::PointPos::start);
                    if (solvext->getEnd() == SolverGeometryExtension::Dependent)
                        geometrymap.emplace_back(geoid,Sketcher::PointPos::start);
                    if (solvext->getMid() == SolverGeometryExtension::Dependent)
                        geometrymap.emplace_back(geoid,Sketcher::PointPos::start);
                }
            }
        }

        geoid++;
    }
}

bool SketchObject::evaluateConstraint(const Constraint *constraint) const
{
    //if requireXXX,  GeoUndef is treated as an error. If not requireXXX,
    //GeoUndef is accepted. Index range checking is done on everything regardless.

    // constraints always require a First!!
    bool requireSecond = false;
    bool requireThird = false;

    switch (constraint->Type) {
        case Radius:
        case Diameter:
        case Weight:
        case Horizontal:
        case Vertical:
        case Distance:
        case DistanceX:
        case DistanceY:
        case Coincident:
        case Perpendicular:
        case Parallel:
        case Equal:
        case PointOnObject:
        case Angle:
            break;
        case Tangent:
            requireSecond = true;
            break;
        case Symmetric:
        case SnellsLaw:
            requireSecond = true;
            requireThird = true;
            break;
        default:
            break;
    }

    int intGeoCount = getHighestCurveIndex() + 1;
    int extGeoCount = getExternalGeometryCount();

    //the actual checks
    bool ret = true;
    int geoId;

    // First is always required and GeoId must be within range
    geoId = constraint->First;
    ret = ret && (geoId >= -extGeoCount && geoId < intGeoCount);

    geoId = constraint->Second;
    ret = ret && ((geoId == GeoEnum::GeoUndef && !requireSecond)
                  ||
                  (geoId >= -extGeoCount && geoId < intGeoCount) );

    geoId = constraint->Third;
    ret = ret && ((geoId == GeoEnum::GeoUndef && !requireThird)
                  ||
                  (geoId >= -extGeoCount && geoId < intGeoCount) );

    return ret;
}

bool SketchObject::evaluateConstraints() const
{
    int intGeoCount = getHighestCurveIndex() + 1;
    int extGeoCount = getExternalGeometryCount();

    std::vector<Part::Geometry *> geometry = getCompleteGeometry();
    const std::vector<Sketcher::Constraint *>& constraints = Constraints.getValuesForce();
    if (static_cast<int>(geometry.size()) != extGeoCount + intGeoCount)
        return false;
    if (geometry.size() < 2)
        return false;

    std::vector<Sketcher::Constraint *>::const_iterator it;
    for (it = constraints.begin(); it != constraints.end(); ++it) {
        if (!evaluateConstraint(*it))
            return false;
    }

    if (!constraints.empty()) {
        if (!Constraints.scanGeometry(geometry))
            return false;
    }

    return true;
}

void SketchObject::validateConstraints()
{
    Base::StateLocker lock(managedoperation, true); // no need to check input data validity as this is an sketchobject managed operation.

    std::vector<Part::Geometry *> geometry = getCompleteGeometry();
    const std::vector<Sketcher::Constraint *>& constraints = Constraints.getValuesForce();

    std::vector<Sketcher::Constraint *> newConstraints;
    newConstraints.reserve(constraints.size());
    std::vector<Sketcher::Constraint *>::const_iterator it;
    for (it = constraints.begin(); it != constraints.end(); ++it) {
        bool valid = evaluateConstraint(*it);
        if (valid)
            newConstraints.push_back(*it);
    }

    if (newConstraints.size() != constraints.size()) {
        Constraints.setValues(std::move(newConstraints));
        acceptGeometry();
    }
    else if (!Constraints.scanGeometry(geometry)) {
        Constraints.acceptGeometry(geometry);
    }
}

std::string SketchObject::validateExpression(const App::ObjectIdentifier &path, std::shared_ptr<const App::Expression> expr)
{
    const App::Property * prop = path.getProperty();

    assert(expr);

    if (!prop)
        return "Property not found";

    if (prop == &Constraints) {
        const Constraint * constraint = Constraints.getConstraint(path);

        if (!constraint->isDriving)
            return "Reference constraints cannot be set!";
    }

    auto deps = expr->getDeps();
    auto it = deps.find(this);
    if (it!=deps.end()) {
        auto it2 = it->second.find("Constraints");
        if (it2 != it->second.end()) {
            for (auto &oid : it2->second) {
                const Constraint * constraint = Constraints.getConstraint(oid);

                if (!constraint->isDriving)
                    return "Reference constraint from this sketch cannot be used in this expression.";
            }
        }
    }
    return "";
}

//This function is necessary for precalculation of an angle when adding
// an angle constraint. It is also used here, in SketchObject, to
// lock down the type of tangency/perpendicularity.
double SketchObject::calculateAngleViaPoint(int GeoId1, int GeoId2, double px, double py)
{
    // Temporary sketch based calculation. Slow, but guaranteed consistency with constraints.
    Sketcher::Sketch sk;

    const Part::Geometry *p1=this->getGeometry(GeoId1);
    const Part::Geometry *p2=this->getGeometry(GeoId2);

    if (p1 && p2) {
        int i1 = sk.addGeometry(this->getGeometry(GeoId1));
        int i2 = sk.addGeometry(this->getGeometry(GeoId2));

        return sk.calculateAngleViaPoint(i1,i2,px,py);
    }
    else
        throw Base::ValueError("Null geometry in calculateAngleViaPoint");
}

void SketchObject::constraintsRenamed(const std::map<App::ObjectIdentifier, App::ObjectIdentifier> &renamed)
{
    ExpressionEngine.renameExpressions(renamed);

    for (auto doc : App::GetApplication().getDocuments())
        doc->renameObjectIdentifiers(renamed);
}

void SketchObject::constraintsRemoved(const std::set<App::ObjectIdentifier> &removed)
{
    std::set<App::ObjectIdentifier>::const_iterator i = removed.begin();

    while (i != removed.end()) {
        ExpressionEngine.setValue(*i, std::shared_ptr<App::Expression>());
        ++i;
    }
}

//Tests if the provided point lies exactly in a curve (satisfies
// point-on-object constraint). It is used to decide whether it is nesessary to
// constrain a point onto curves when 3-element selection tangent-via-point-like
// constraints are applied.
bool SketchObject::isPointOnCurve(int geoIdCurve, double px, double py)
{
    //DeepSOIC: this may be slow, but I wanted to reuse the existing code
    Sketcher::Sketch sk;
    int icrv = sk.addGeometry(this->getGeometry(geoIdCurve));
    Base::Vector3d pp;
    pp.x = px; pp.y = py;
    Part::GeomPoint p(pp);
    int ipnt = sk.addPoint(p);
    int icstr = sk.addPointOnObjectConstraint(ipnt, Sketcher::PointPos::start, icrv);
    double err = sk.calculateConstraintError(icstr);
    return err*err < 10.0*sk.getSolverPrecision();
}

//This one was done just for fun to see to what precision the constraints are solved.
double SketchObject::calculateConstraintError(int ConstrId)
{
    Sketcher::Sketch sk;
    const std::vector<Constraint *> &clist = this->Constraints.getValues();
    if (ConstrId < 0 || ConstrId >= int(clist.size()))
        return std::numeric_limits<double>::quiet_NaN();

    Constraint* cstr = clist[ConstrId]->clone();
    double result=0.0;
    try{
        std::vector<int> GeoIdList;
        int g;
        GeoIdList.push_back(cstr->First);
        GeoIdList.push_back(cstr->Second);
        GeoIdList.push_back(cstr->Third);

        //add only necessary geometry to the sketch
        for(std::size_t i=0; i<GeoIdList.size(); i++){
            g = GeoIdList[i];
            if (g != GeoEnum::GeoUndef){
                GeoIdList[i] = sk.addGeometry(this->getGeometry(g));
            }
        }

        cstr->First = GeoIdList[0];
        cstr->Second = GeoIdList[1];
        cstr->Third = GeoIdList[2];
        int icstr = sk.addConstraint(cstr);
        result = sk.calculateConstraintError(icstr);
    } catch(...) {//cleanup
        delete cstr;
        throw;
    }
    delete cstr;
    return result;
}

PyObject *SketchObject::getPyObject()
{
    if (PythonObject.is(Py::_None())) {
        // ref counter is set to 1
        PythonObject = Py::Object(new SketchObjectPy(this),true);
    }
    return Py::new_reference_to(PythonObject);
}

unsigned int SketchObject::getMemSize() const
{
    return 0;
}

void SketchObject::Save(Writer &writer) const
{
    // save the father classes
    Part::Part2DObject::Save(writer);
}

void SketchObject::Restore(XMLReader &reader)
{
    // read the father classes
    Part::Part2DObject::Restore(reader);
}

void SketchObject::onChanged(const App::Property* prop)
{
    if (isRestoring() && prop == &Geometry) {
        std::vector<Part::Geometry*> geom = Geometry.getValues();
        std::vector<Part::Geometry*> supportedGeom = supportedGeometry(geom);
        // To keep upward compatibility ignore unsupported geometry types
        if (supportedGeom.size() != geom.size()) {
            Geometry.setValues(supportedGeom);
            return;
        }
    }

    if (prop == &Geometry || prop == &Constraints) {

        auto doc = getDocument();

        if(doc && doc->isPerformingTransaction()) { // undo/redo
            setStatus(App::PendingTransactionUpdate, true);
        }
        else {
            if(!internaltransaction) { // internal sketchobject operations changing both geometry and constraints will explicitly perform an update
                if(prop == &Geometry) {
                    if(managedoperation || isRestoring()) {
                        acceptGeometry(); // if geometry changed, the constraint geometry indices must be updated
                    }
                    else { // this change was not effect via SketchObject, but using direct access to properties, check input data

                        // declares constraint invalid if indices go beyond the geometry and any call to getValues with return an empty list until this is fixed.
                        bool invalidinput = Constraints.checkConstraintIndices(getHighestCurveIndex(),-getExternalGeometryCount());

                        if(!invalidinput) {
                            acceptGeometry();
                        }
                        else {
                            Base::Console().Error("SketchObject::onChanged(): Unmanaged change of Geometry Property results in invalid constraint indices\n");
                        }
                    }
                }
                else { // Change is in Constraints

                    if(managedoperation || isRestoring()) {
                        Constraints.checkGeometry(getCompleteGeometry());
                    }
                    else { // this change was not effect via SketchObject, but using direct access to properties, check input data

                        // declares constraint invalid if indices go beyond the geometry and any call to getValues with return an empty list until this is fixed.
                        bool invalidinput = Constraints.checkConstraintIndices(getHighestCurveIndex(),-getExternalGeometryCount());

                        if(!invalidinput) {
                            if (Constraints.checkGeometry(getCompleteGeometry())) { // if there are invalid geometry indices in the constraints, we need to update them
                                acceptGeometry();
                            }
                        }
                        else {
                            Base::Console().Error("SketchObject::onChanged(): Unmanaged change of Constraint Property results in invalid constraint indices\n");
                        }

                    }
                }
            }
        }
    }
    else if (prop == &ExternalGeometry) {
        // make sure not to change anything while restoring this object
        if (!isRestoring()) {
            // external geometry was cleared
            if (ExternalGeometry.getSize() == 0) {
                delConstraintsToExternal();
            }
        }
    }
#if 0
    // For now do not delete anything (#0001791). When changing the support
    // face it might be better to check which external geometries can be kept.
    else if (prop == &Support) {
        // make sure not to change anything while restoring this object
        if (!isRestoring()) {
            // if support face has changed then clear the external geometry
            delConstraintsToExternal();
            for (int i=0; i < getExternalGeometryCount(); i++) {
                delExternal(0);
            }
        }
    }
#endif
    Part::Part2DObject::onChanged(prop);
}

void SketchObject::onUndoRedoFinished()
{
    // upon undo/redo, PropertyConstraintList does not have updated valid geometry keys, which results in empty constraint lists
    // when using getValues
    //
    // The sketch will also have invalid vertex indices, requiring a call to rebuildVertexIndex
    //
    // Historically this was "solved" by issuing a recompute, which is absolutely unnecessary and prevents solve() from working before
    // such a recompute
    Constraints.checkConstraintIndices(getHighestCurveIndex(),-getExternalGeometryCount()); // in case it is redoing an operation with invalid data.
    acceptGeometry();
    synchroniseGeometryState();
    solve();
}

void SketchObject::synchroniseGeometryState()
{
    const std::vector< Part::Geometry * > &vals = getInternalGeometry();

    for(size_t i = 0 ; i < vals.size() ; i++) {
        auto gf = GeometryFacade::getFacade(vals[i]);

        auto facadeInternalAlignment = gf->getInternalType();
        auto facadeBlockedState = gf->getBlocked();

        Sketcher::InternalType::InternalType constraintInternalAlignment = InternalType::None;
        bool constraintBlockedState = false;

        for (auto cstr : Constraints.getValues()) {
            if(cstr->First == int(i)) {
                getInternalTypeState(cstr, constraintInternalAlignment);
                getBlockedState(cstr, constraintBlockedState);
            }
        }

        if(constraintInternalAlignment != facadeInternalAlignment)
            gf->setInternalType(constraintInternalAlignment);

        if(constraintBlockedState != facadeBlockedState)
            gf->setBlocked(constraintBlockedState);

    }
}

bool SketchObject::getInternalTypeState(const Constraint * cstr, Sketcher::InternalType::InternalType & internaltypestate) const
{
    if(cstr->Type == InternalAlignment) {

        switch(cstr->AlignmentType){
            case Undef:
            case NumInternalAlignmentType:
                internaltypestate = InternalType::None;
                break;
            case EllipseMajorDiameter:
                internaltypestate = InternalType::EllipseMajorDiameter;
                break;
            case EllipseMinorDiameter:
                internaltypestate = InternalType::EllipseMinorDiameter;
                break;
            case EllipseFocus1:
                internaltypestate = InternalType::EllipseFocus1;
                break;
            case EllipseFocus2:
                internaltypestate = InternalType::EllipseFocus2;
                break;
            case HyperbolaMajor:
                internaltypestate = InternalType::HyperbolaMajor;
                break;
            case HyperbolaMinor:
                internaltypestate = InternalType::HyperbolaMinor;
                break;
            case HyperbolaFocus:
                internaltypestate = InternalType::HyperbolaFocus;
                break;
            case ParabolaFocus:
                internaltypestate = InternalType::ParabolaFocus;
                break;
            case BSplineControlPoint:
                internaltypestate = InternalType::BSplineControlPoint;
                break;
            case BSplineKnotPoint:
                internaltypestate = InternalType::BSplineKnotPoint;
                break;
            case ParabolaFocalAxis:
                internaltypestate = InternalType::ParabolaFocalAxis;
                break;
        }

        return true;
    }

    return false;
}

bool SketchObject::getBlockedState(const Constraint * cstr, bool & blockedstate) const
{
    if(cstr->Type == Block) {
        blockedstate = true;
        return true;
    }

    return false;
}

void SketchObject::onDocumentRestored()
{
    try {
        restoreFinished();
        Part::Part2DObject::onDocumentRestored();
    }
    catch (...) {
    }
}

void SketchObject::restoreFinished()
{
    try {
        migrateSketch();

        validateExternalLinks();
        rebuildExternalGeometry();
        Constraints.acceptGeometry(getCompleteGeometry());
        synchroniseGeometryState();
        // this may happen when saving a sketch directly in edit mode
        // but never performed a recompute before
        if (Shape.getValue().IsNull() && hasConflicts() == 0) {
            if (this->solve(true) == 0)
                Shape.setValue(solvedSketch.toShape());
        }
    }
    catch (...) {
    }
}

void SketchObject::migrateSketch()
{
    bool noextensions = false;

    for( const auto & g : getInternalGeometry() )
        if(!g->hasExtension(SketchGeometryExtension::getClassTypeId())) // no extension - legacy file
            noextensions = true;

    if(noextensions) {
        for( auto c : Constraints.getValues()) {

            addGeometryState(c);

            // Convert B-Spline controlpoints radius/diameter constraints to Weight constraints
            if(c->Type == InternalAlignment && c->AlignmentType == BSplineControlPoint) {
                int circlegeoid = c->First;
                int bsplinegeoid = c->Second;

                auto bsp = static_cast<const Part::GeomBSplineCurve*>(getGeometry(bsplinegeoid));

                std::vector<double> weights = bsp->getWeights();

                for( auto ccp : Constraints.getValues()) {

                    if( (ccp->Type == Radius || ccp->Type == Diameter ) &&
                        ccp->First == circlegeoid ) {

                        if(c->InternalAlignmentIndex < int(weights.size())) {
                            ccp->Type = Weight;
                            ccp->setValue(weights[c->InternalAlignmentIndex]);

                        }
                    }
                }
            }
        }

        // Construction migration to extension
        for( auto g : Geometry.getValues()) {

            if(g->hasExtension(Part::GeometryMigrationExtension::getClassTypeId()))
            {
                auto ext = std::static_pointer_cast<Part::GeometryMigrationExtension>(
                                g->getExtension(Part::GeometryMigrationExtension::getClassTypeId()).lock());

                if(ext->testMigrationType(Part::GeometryMigrationExtension::Construction))
                {
                    auto gf = GeometryFacade::getFacade(g); // at this point IA geometry is already migrated

                    bool oldconstr =  ext->getConstruction();

                    if( g->getTypeId() == Part::GeomPoint::getClassTypeId() && !gf->isInternalAligned())
                        oldconstr = true;

                    GeometryFacade::setConstruction(g,oldconstr);
                }

                g->deleteExtension(Part::GeometryMigrationExtension::getClassTypeId());
            }

        }
    }

    /* parabola axis as internal geometry */
    auto constraints = Constraints.getValues();
    auto geometries = getInternalGeometry();

    auto parabolafound = std::find_if(geometries.begin(), geometries.end(),
                                [](auto g){
                                    return g->getTypeId() == Part::GeomArcOfParabola::getClassTypeId();
                                });

    if(parabolafound != geometries.end()) {

        auto focalaxisfound = std::find_if(constraints.begin(), constraints.end(),
                                    [](auto c){
                                        return c->Type == InternalAlignment && c->AlignmentType == ParabolaFocalAxis;
                                    });

        // There are parabolas and there isn't an IA axis. (1) there are no axis or (2) there is a legacy construction line
        if(focalaxisfound == constraints.end()) {

            // maps parabola geoid to focusgeoid
            std::map<int,int> parabolageoid2focusgeoid;

            // populate parabola and focus geoids
            for(const auto & c : constraints) {
                if(c->Type == InternalAlignment && c->AlignmentType == ParabolaFocus) {
                    parabolageoid2focusgeoid[c->Second] = {c->First};
                }
            }

            // maps axis geoid to parabolageoid
            std::map<int,int> axisgeoid2parabolageoid;

            // populate axis geoid
            for(const auto & [parabolageoid, focusgeoid] : parabolageoid2focusgeoid ) {
                // look for a line from focusgeoid:start to Geoid:mid_external
                std::vector<int> focusgeoidlistgeoidlist;
                std::vector<PointPos> focusposidlist;
                getDirectlyCoincidentPoints(focusgeoid, Sketcher::PointPos::start, focusgeoidlistgeoidlist,
                                                focusposidlist);

                std::vector<int> parabgeoidlistgeoidlist;
                std::vector<PointPos> parabposidlist;
                getDirectlyCoincidentPoints(parabolageoid, Sketcher::PointPos::mid, parabgeoidlistgeoidlist,
                                            parabposidlist);

                if (!focusgeoidlistgeoidlist.empty() && !parabgeoidlistgeoidlist.empty()) {
                    std::size_t i,j;
                    for(i=0;i<focusgeoidlistgeoidlist.size();i++) {
                        for(j=0;j<parabgeoidlistgeoidlist.size();j++) {
                            if(focusgeoidlistgeoidlist[i] == parabgeoidlistgeoidlist[j]) {
                                axisgeoid2parabolageoid[focusgeoidlistgeoidlist[i]] = parabolageoid;
                            }
                        }
                    }
                }
            }

            std::vector<Constraint *> newconstraints;
            newconstraints.reserve(constraints.size());

            for(const auto & c : constraints) {

                if(c->Type != Coincident) {
                    newconstraints.push_back(c);
                }
                else {
                    auto axismajorcoincidentfound = std::find_if(axisgeoid2parabolageoid.begin(), axisgeoid2parabolageoid.end(),
                                                        [&] (const auto & pair) {
                                                            auto parabolageoid = pair.second;
                                                            auto axisgeoid = pair.first;
                                                            return (c->First == axisgeoid && c->Second == parabolageoid && c->SecondPos == PointPos::mid) ||
                                                                   (c->Second == axisgeoid && c->First == parabolageoid && c->FirstPos == PointPos::mid);
                                                        });

                    if(axismajorcoincidentfound != axisgeoid2parabolageoid.end()) {
                        continue; // we skip this coincident, the other coincident on axis will be substituted by internal geometry constraint
                    }

                    auto focuscoincidentfound = std::find_if(axisgeoid2parabolageoid.begin(), axisgeoid2parabolageoid.end(),
                                                        [&] (const auto & pair) {
                                                            auto parabolageoid = pair.second;
                                                            auto axisgeoid = pair.first;
                                                            auto focusgeoid = parabolageoid2focusgeoid[parabolageoid];
                                                            return (c->First == axisgeoid && c->Second == focusgeoid && c->SecondPos == PointPos::start) ||
                                                                   (c->Second == axisgeoid && c->First == focusgeoid && c->FirstPos == PointPos::start);
                                                        });

                    if(focuscoincidentfound != axisgeoid2parabolageoid.end()) {
                        Sketcher::Constraint *newConstr = new Sketcher::Constraint();
                        newConstr->Type = Sketcher::InternalAlignment;
                        newConstr->AlignmentType = Sketcher::ParabolaFocalAxis;
                        newConstr->First = focuscoincidentfound->first; // axis geoid
                        newConstr->FirstPos = Sketcher::PointPos::none;
                        newConstr->Second = focuscoincidentfound->second; // parabola geoid
                        newConstr->SecondPos = Sketcher::PointPos::none;
                        newconstraints.push_back(newConstr);

                        addGeometryState(newConstr);

                        continue; // we skip the coincident, as we have substituted it by internal geometry constraint
                    }

                    newconstraints.push_back(c);
                }
            }

            Constraints.setValues(std::move(newconstraints));

            Base::Console().Critical(this->getFullName(),QT_TRANSLATE_NOOP("Notifications","Parabolas were migrated. Migrated files won't open in previous versions of FreeCAD!!\n"));
        }
    }
}

void SketchObject::getGeoVertexIndex(int VertexId, int &GeoId, PointPos &PosId) const
{
    if (VertexId < 0 || VertexId >= int(VertexId2GeoId.size())) {
        GeoId = GeoEnum::GeoUndef;
        PosId = PointPos::none;
        return;
    }
    GeoId = VertexId2GeoId[VertexId];
    PosId = VertexId2PosId[VertexId];
}

int SketchObject::getVertexIndexGeoPos(int GeoId, PointPos PosId) const
{
    for(std::size_t i=0;i<VertexId2GeoId.size();i++) {
        if(VertexId2GeoId[i]==GeoId && VertexId2PosId[i]==PosId)
            return i;
    }

    return -1;
}

///changeConstraintsLocking locks or unlocks all tangent and perpendicular
/// constraints. (Constraint locking prevents it from flipping to another valid
/// configuration, when e.g. external geometry is updated from outside.) The
/// sketch solve is not triggered by the function, but the SketchObject is
/// touched (a recompute will be necessary). The geometry should not be affected
/// by the function.
///The bLock argument specifies, what to do. If true, all constraints are
/// unlocked and locked again. If false, all tangent and perp. constraints are
/// unlocked.
int SketchObject::changeConstraintsLocking(bool bLock)
{
    Base::StateLocker lock(managedoperation, true); // no need to check input data validity as this is an sketchobject managed operation.

    int cntSuccess = 0;
    int cntToBeAffected = 0;//==cntSuccess+cntFail
    const std::vector< Constraint * > &vals = this->Constraints.getValues();

    std::vector< Constraint * > newVals(vals);//modifiable copy of pointers array

    for(size_t i=0; i<newVals.size(); i++) {
        if( newVals[i]->Type == Tangent || newVals[i]->Type == Perpendicular ){
            //create a constraint copy, affect it, replace the pointer
            cntToBeAffected++;
            Constraint *constNew = newVals[i]->clone();
            bool ret = AutoLockTangencyAndPerpty(newVals[i], /*bForce=*/true, bLock);

            if (ret)
                cntSuccess++;

            newVals[i] = constNew;
            Base::Console().Log("Constraint%i will be affected\n",
                                i+1);
        }
    }

    this->Constraints.setValues(std::move(newVals));

    Base::Console().Log("ChangeConstraintsLocking: affected %i of %i tangent/perp constraints\n",
                        cntSuccess, cntToBeAffected);

    return cntSuccess;
}

bool SketchObject::constraintHasExpression(int constrid) const
{
    App::ObjectIdentifier spath = this->Constraints.createPath(constrid);

    App::PropertyExpressionEngine::ExpressionInfo expr_info = this->getExpression(spath);

    return (expr_info.expression != nullptr);
}


/*!
 * \brief SketchObject::port_reversedExternalArcs finds constraints that link to endpoints of external-geometry arcs,
 *  and swaps the endpoints in the constraints. This is needed after CCW emulation was introduced, to port old sketches.
 * \param justAnalyze if true, nothing is actually done - only the number of constraints to be affected is returned.
 * \return the number of constraints changed/to be changed.
 */
int SketchObject::port_reversedExternalArcs(bool justAnalyze)
{
    Base::StateLocker lock(managedoperation, true); // no need to check input data validity as this is an sketchobject managed operation.

    int cntToBeAffected = 0;//==cntSuccess+cntFail
    const std::vector< Constraint * > &vals = this->Constraints.getValues();

    std::vector< Constraint * > newVals(vals);//modifiable copy of pointers array

    for(std::size_t ic = 0; ic<newVals.size(); ic++){//ic = index of constraint
        bool affected=false;
        Constraint *constNew = nullptr;
        for(int ig=1; ig<=3; ig++){//cycle through constraint.first, second, third
            int geoId = 0;
            Sketcher::PointPos posId = PointPos::none;
            switch (ig){
                case 1: geoId=newVals[ic]->First; posId = newVals[ic]->FirstPos; break;
                case 2: geoId=newVals[ic]->Second; posId = newVals[ic]->SecondPos; break;
                case 3: geoId=newVals[ic]->Third; posId = newVals[ic]->ThirdPos; break;
            }

            if ( geoId <= GeoEnum::RefExt &&
                 (posId==Sketcher::PointPos::start || posId==Sketcher::PointPos::end)){
                //we are dealing with a link to an endpoint of external geom
                Part::Geometry* g = this->ExternalGeo[-geoId-1];
                if (g->getTypeId() == Part::GeomArcOfCircle::getClassTypeId()){
                    const Part::GeomArcOfCircle *segm = static_cast<const Part::GeomArcOfCircle*>(g);
                    if (segm->isReversed()){
                        //Gotcha! a link to an endpoint of external arc that is reversed.
                        //create a constraint copy, affect it, replace the pointer
                        if (!affected)
                            constNew = newVals[ic]->clone();
                        affected=true;
                        //Do the fix on temp vars
                        if(posId == Sketcher::PointPos::start)
                            posId = Sketcher::PointPos::end;
                        else if (posId == Sketcher::PointPos::end)
                            posId = Sketcher::PointPos::start;
                    }
                }
            }
            if (!affected) continue;
            //Propagate the fix made on temp vars to the constraint
            switch (ig){
                case 1: constNew->First = geoId; constNew->FirstPos = posId; break;
                case 2: constNew->Second = geoId; constNew->SecondPos = posId; break;
                case 3: constNew->Third = geoId; constNew->ThirdPos = posId; break;
            }
        }
        if (affected){
            cntToBeAffected++;
            newVals[ic] = constNew;
            Base::Console().Log("Constraint%i will be affected\n",
                                ic+1);
        };
    }

    if(!justAnalyze){
        this->Constraints.setValues(std::move(newVals));
        Base::Console().Log("Swapped start/end of reversed external arcs in %i constraints\n",
                            cntToBeAffected);
    }

    return cntToBeAffected;
}

///Locks tangency/perpendicularity type of such a constraint.
///The constraint passed must be writable (i.e. the one that is not
/// yet in the constraint list).
///Tangency type (internal/external) is derived from current geometry
/// the constraint refers to.
///Same for perpendicularity type.
///
///This function catches exceptions, because it's not a reason to
/// not create a constraint if tangency/perp-ty type cannot be determined.
///
///Arguments:
/// cstr - pointer to a constraint to be locked/unlocked
/// bForce - specifies whether to ignore the already locked constraint or not.
/// bLock - specifies whether to lock the constraint or not (if bForce is
///  true, the constraint gets unlocked, otherwise nothing is done at all).
///
///Return values:
/// true - success.
/// false - fail (this indicates an error, or that a constraint locking isn't supported).
bool SketchObject::AutoLockTangencyAndPerpty(Constraint *cstr, bool bForce, bool bLock)
{
    try {
        //assert ( cstr->Type == Tangent  ||  cstr->Type == Perpendicular);
        if(cstr->getValue() != 0.0 && ! bForce) /*tangency type already set. If not bForce - don't touch.*/
            return true;
        if(!bLock){
            cstr->setValue(0.0);//reset
        } else {
            //decide on tangency type. Write the angle value into the datum field of the constraint.
            int geoId1, geoId2, geoIdPt;
            PointPos posPt;
            geoId1 = cstr->First;
            geoId2 = cstr->Second;
            geoIdPt = cstr->Third;
            posPt = cstr->ThirdPos;
            if (geoIdPt == GeoEnum::GeoUndef){//not tangent-via-point, try endpoint-to-endpoint...

                // First check if it is a tangency at knot constraint, if not continue with checking for endpoints.
                // Endpoint constraints make use of the AngleViaPoint framework at solver level, so they need locking
                // angle calculation, tangency at knot constraint does not.
                auto geof = getGeometryFacade(cstr->First);
                if(geof->isInternalType(InternalType::BSplineKnotPoint)) {
                    // there is point that is a B-Spline knot in a two element constraint
                    // this is not implement using AngleViaPoint (TangencyViaPoint)
                    return false;
                }

                geoIdPt = cstr->First;
                posPt = cstr->FirstPos;
            }
            if (posPt == PointPos::none){//not endpoint-to-curve and not endpoint-to-endpoint tangent (is simple tangency)
                //no tangency lockdown is implemented for simple tangency. Do nothing.
                return false;
            }
            else {
                Base::Vector3d p = getPoint(geoIdPt, posPt);

                //this piece of code is also present in Sketch.cpp, correct for offset
                //and to do the autodecision for old sketches.
                double angleOffset = 0.0;//the difference between the datum value and the actual angle to apply. (datum=angle+offset)
                double angleDesire = 0.0;//the desired angle value (and we are to decide if 180* should be added to it)
                if (cstr->Type == Tangent) {angleOffset = -M_PI/2; angleDesire = 0.0;}
                if (cstr->Type == Perpendicular) {angleOffset = 0; angleDesire = M_PI/2;}

                double angleErr = calculateAngleViaPoint(geoId1, geoId2, p.x, p.y) - angleDesire;

                //bring angleErr to -pi..pi
                if (angleErr > M_PI) angleErr -= M_PI*2;
                if (angleErr < -M_PI) angleErr += M_PI*2;

                //the autodetector
                if(fabs(angleErr) > M_PI/2 )
                    angleDesire += M_PI;

                cstr->setValue(angleDesire + angleOffset); //external tangency. The angle stored is offset by Pi/2 so that a value of 0.0 is invalid and treated as "undecided".
            }
        }
    }
    catch (Base::Exception& e){
        //failure to determine tangency type is not a big deal, so a warning.
        Base::Console().Warning("Error in AutoLockTangency. %s \n", e.what());
        return false;
    }
    return true;
}

void SketchObject::setExpression(const App::ObjectIdentifier &path, std::shared_ptr<App::Expression> expr)
{
    DocumentObject::setExpression(path, expr);

    if(noRecomputes) {// if we do not have a recompute, the sketch must be solved to update the DoF of the solver, constraints and UI
        try {
            auto res = ExpressionEngine.execute();
            if(res) {
                FC_ERR("Failed to recompute " << ExpressionEngine.getFullName() << ": " << res->Why);
                delete res;
            }
        } catch (Base::Exception &e) {
            e.ReportException();
            FC_ERR("Failed to recompute " << ExpressionEngine.getFullName() << ": " << e.what());
        }
        solve();
    }
}

int SketchObject::autoConstraint(double precision, double angleprecision, bool includeconstruction)
{
    return analyser->autoconstraint(precision, angleprecision, includeconstruction);
}

int SketchObject::detectMissingPointOnPointConstraints(double precision, bool includeconstruction)
{
    return analyser->detectMissingPointOnPointConstraints(precision, includeconstruction);
}

void SketchObject::analyseMissingPointOnPointCoincident(double angleprecision)
{
    analyser->analyseMissingPointOnPointCoincident(angleprecision);
}

int SketchObject::detectMissingVerticalHorizontalConstraints(double angleprecision)
{
    return analyser->detectMissingVerticalHorizontalConstraints(angleprecision);
}

int SketchObject::detectMissingEqualityConstraints(double precision)
{
    return analyser->detectMissingEqualityConstraints(precision);
}

std::vector<ConstraintIds> & SketchObject::getMissingPointOnPointConstraints()
{
    return analyser->getMissingPointOnPointConstraints();
}

std::vector<ConstraintIds> & SketchObject::getMissingVerticalHorizontalConstraints()
{
    return analyser->getMissingVerticalHorizontalConstraints();
}

std::vector<ConstraintIds> & SketchObject::getMissingLineEqualityConstraints()
{
    return analyser->getMissingLineEqualityConstraints();
}

std::vector<ConstraintIds> & SketchObject::getMissingRadiusConstraints()
{
    return analyser->getMissingRadiusConstraints();
}

void SketchObject::setMissingRadiusConstraints(std::vector<ConstraintIds> &cl)
{
    if(analyser)
        analyser->setMissingRadiusConstraints(cl);
}

void SketchObject::setMissingLineEqualityConstraints(std::vector<ConstraintIds>& cl)
{
    if(analyser)
        analyser->setMissingLineEqualityConstraints(cl);
}

void SketchObject::setMissingVerticalHorizontalConstraints(std::vector<ConstraintIds>& cl)
{
    if(analyser)
        analyser->setMissingVerticalHorizontalConstraints(cl);
}

void SketchObject::setMissingPointOnPointConstraints(std::vector<ConstraintIds>& cl)
{
    if(analyser)
        analyser->setMissingPointOnPointConstraints(cl);
}

void SketchObject::makeMissingPointOnPointCoincident(bool onebyone)
{
    if(analyser)
        analyser->makeMissingPointOnPointCoincident(onebyone);
}

void SketchObject::makeMissingVerticalHorizontal(bool onebyone)
{
    if(analyser)
        analyser->makeMissingVerticalHorizontal(onebyone);
}

void SketchObject::makeMissingEquality(bool onebyone)
{
    if(analyser)
        analyser->makeMissingEquality(onebyone);
}

int SketchObject::autoRemoveRedundants(bool updategeo)
{
    auto redundants = getLastRedundant();

    if(redundants.empty())
        return 0;

    for(size_t i=0;i<redundants.size();i++) // getLastRedundant is base 1, while delConstraints is base 0
        redundants[i]--;

    delConstraints(redundants,updategeo);

    return redundants.size();
}

int SketchObject::renameConstraint(int GeoId, std::string name)
{
    // only change the constraint item if the names are different
    const Constraint* item = Constraints[GeoId];

    if (item->Name != name) {
        Base::StateLocker lock(managedoperation, true); // no need to check input data validity as this is an sketchobject managed operation.

        Constraint* copy = item->clone();
        copy->Name = name;

        Constraints.set1Value(GeoId, copy);
        delete copy;

        solverNeedsUpdate = true; // make sure any prospective solver access updates the constraint pointer that just got invalidated

        return 0;
    }
    return -1;
}

std::vector<Base::Vector3d> SketchObject::getOpenVertices() const
{
    std::vector<Base::Vector3d> points;

    if(analyser)
        points = analyser->getOpenVertices();

    return points;
}

// SketchGeometryExtension interface

int SketchObject::setGeometryId(int GeoId, long id)
{
    Base::StateLocker lock(managedoperation, true); // no need to check input data validity as this is an sketchobject managed operation.

    if (GeoId < 0 || GeoId >= int(Geometry.getValues().size()))
        return -1;

    const std::vector< Part::Geometry * > &vals = getInternalGeometry();



    std::vector< Part::Geometry * > newVals(vals);

    // deep copy
    for(size_t i=0; i<newVals.size(); i++) {
        newVals[i] = newVals[i]->clone();

        if((int)i == GeoId) {
            auto gf = GeometryFacade::getFacade(newVals[i]);

            gf->setId(id);
        }
    }

    // There is not actual internal transaction going on here, however neither the geometry indices nor the vertices need to be updated
    // so this is a convenient way of preventing it.
    {
        Base::StateLocker lock(internaltransaction, true);
        this->Geometry.setValues(std::move(newVals));
    }

    return 0;
}

int SketchObject::getGeometryId(int GeoId, long &id) const
{
   if (GeoId < 0 || GeoId >= int(Geometry.getValues().size()))
        return -1;

   const std::vector< Part::Geometry * > &vals = getInternalGeometry();

   auto gf = GeometryFacade::getFacade(vals[GeoId]);

   id = gf->getId();

   return 0;
}

// Python Sketcher feature ---------------------------------------------------------

namespace App {
/// @cond DOXERR
PROPERTY_SOURCE_TEMPLATE(Sketcher::SketchObjectPython, Sketcher::SketchObject)
template<> const char* Sketcher::SketchObjectPython::getViewProviderName() const {
    return "SketcherGui::ViewProviderPython";
}
template<> PyObject* Sketcher::SketchObjectPython::getPyObject() {
    if (PythonObject.is(Py::_None())) {
        // ref counter is set to 1
        PythonObject = Py::Object(new FeaturePythonPyT<SketchObjectPy>(this),true);
    }
    return Py::new_reference_to(PythonObject);
}
/// @endcond

// explicit template instantiation
template class SketcherExport FeaturePythonT<Sketcher::SketchObject>;
}