PartDesign: Add transparent previews

src/Mod/Part/App/AppPart.cpp

@@ -98,6 +98,7 @@
 #include "GeometryIntExtensionPy.h"
 #include "GeometryMigrationExtension.h"
 #include "GeometryStringExtensionPy.h"
+#include "PreviewExtension.h"
 #include "HyperbolaPy.h"
 #include "ImportStep.h"
 #include "LinePy.h"
@@ -435,7 +436,7 @@ PyMOD_INIT_FUNC(Part)
 
     Part::AttachExtension       ::init();
     Part::AttachExtensionPython ::init();
-
+    Part::PreviewExtension      ::init();
     Part::PrismExtension        ::init();
 
     Part::Feature               ::init();

src/Mod/Part/App/CMakeLists.txt

@@ -225,6 +225,8 @@ SET(Features_SRCS
     DatumFeature.h
     AttachExtension.h
     AttachExtension.cpp
+    PreviewExtension.cpp
+    PreviewExtension.h
     PrismExtension.cpp
     PrismExtension.h
     VectorAdapter.cpp

src/Mod/Part/App/PreviewExtension.cpp

@@ -0,0 +1,67 @@
+// SPDX-License-Identifier: LGPL-2.1-or-later
+/****************************************************************************
+ *                                                                          *
+ *   Copyright (c) 2025 Kacper Donat <kacper@kadet.net>                     *
+ *                                                                          *
+ *   This file is part of FreeCAD.                                          *
+ *                                                                          *
+ *   FreeCAD is free software: you can redistribute it and/or modify it     *
+ *   under the terms of the GNU Lesser General Public License as            *
+ *   published by the Free Software Foundation, either version 2.1 of the   *
+ *   License, or (at your option) any later version.                        *
+ *                                                                          *
+ *   FreeCAD 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       *
+ *   Lesser General Public License for more details.                        *
+ *                                                                          *
+ *   You should have received a copy of the GNU Lesser General Public       *
+ *   License along with FreeCAD. If not, see                                *
+ *   <https://www.gnu.org/licenses/>.                                       *
+ *                                                                          *
+ ***************************************************************************/
+
+#include "PreCompiled.h"
+
+#include "PreviewExtension.h"
+
+#include <App/DocumentObject.h>
+
+EXTENSION_PROPERTY_SOURCE(Part::PreviewExtension, App::DocumentObjectExtension)
+EXTENSION_PROPERTY_SOURCE_TEMPLATE(Part::PreviewExtensionPython, Part::PreviewExtension)
+
+Part::PreviewExtension::PreviewExtension()
+{
+    initExtensionType(getExtensionClassTypeId());
+
+    EXTENSION_ADD_PROPERTY(PreviewShape, (TopoShape()));
+
+    PreviewShape.setStatus(App::Property::Output, true);
+    PreviewShape.setStatus(App::Property::Transient, true);
+    PreviewShape.setStatus(App::Property::Hidden, true);
+}
+
+void Part::PreviewExtension::updatePreview()
+{
+    if (_isPreviewFresh) {
+        return;
+    }
+
+    recomputePreview();
+
+    _isPreviewFresh = true;
+}
+
+bool Part::PreviewExtension::mustRecomputePreview() const
+{
+    return getExtendedObject()->mustRecompute();
+}
+
+void Part::PreviewExtension::extensionOnChanged(const App::Property* prop)
+{
+    DocumentObjectExtension::extensionOnChanged(prop);
+
+    if (mustRecomputePreview()) {
+        _isPreviewFresh = false;
+    }
+}

src/Mod/Part/App/PreviewExtension.h

@@ -0,0 +1,82 @@
+// SPDX-License-Identifier: LGPL-2.1-or-later
+/****************************************************************************
+ *                                                                          *
+ *   Copyright (c) 2025 Kacper Donat <kacper@kadet.net>                     *
+ *                                                                          *
+ *   This file is part of FreeCAD.                                          *
+ *                                                                          *
+ *   FreeCAD is free software: you can redistribute it and/or modify it     *
+ *   under the terms of the GNU Lesser General Public License as            *
+ *   published by the Free Software Foundation, either version 2.1 of the   *
+ *   License, or (at your option) any later version.                        *
+ *                                                                          *
+ *   FreeCAD 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       *
+ *   Lesser General Public License for more details.                        *
+ *                                                                          *
+ *   You should have received a copy of the GNU Lesser General Public       *
+ *   License along with FreeCAD. If not, see                                *
+ *   <https://www.gnu.org/licenses/>.                                       *
+ *                                                                          *
+ ***************************************************************************/
+
+#ifndef PART_PREVIEWEXTENSION_H
+#define PART_PREVIEWEXTENSION_H
+
+#include "PropertyTopoShape.h"
+
+#include <App/DocumentObject.h>
+#include <App/DocumentObjectExtension.h>
+#include <App/ExtensionPython.h>
+
+namespace Part
+{
+
+class PartExport PreviewExtension: public App::DocumentObjectExtension
+{
+    EXTENSION_PROPERTY_HEADER_WITH_OVERRIDE(Part::PreviewExtension);
+    using inherited = DocumentObjectExtension;
+
+public:
+    /// Shape displayed as a semi-transparent preview, should be a delta between current state and
+    /// previous one
+    PropertyPartShape PreviewShape;
+
+    PreviewExtension();
+
+    bool isPreviewFresh() const
+    {
+        return _isPreviewFresh;
+    }
+
+    void updatePreview();
+
+    virtual bool mustRecomputePreview() const;
+
+protected:
+    void extensionOnChanged(const App::Property* prop) override;
+
+    virtual App::DocumentObjectExecReturn* recomputePreview()
+    {
+        return App::DocumentObject::StdReturn;
+    };
+
+private:
+    bool _isPreviewFresh {false};
+};
+
+template<typename ExtensionT>
+class PreviewExtensionPythonT: public ExtensionT
+{
+
+public:
+    PreviewExtensionPythonT() = default;
+    ~PreviewExtensionPythonT() override = default;
+};
+
+using PreviewExtensionPython = App::ExtensionPythonT<PreviewExtensionPythonT<PreviewExtension>>;
+
+}  // namespace Part
+
+#endif  // PART_PREVIEWEXTENSION_H

src/Mod/Part/App/Tools.cpp

@@ -71,7 +71,11 @@
 
 #include "Tools.h"
 
+#include <TopExp_Explorer.hxx>
+#include <TopoShape.h>
 
+
+class TopExp_Explorer;
 void Part::closestPointsOnLines(const gp_Lin& lin1, const gp_Lin& lin2, gp_Pnt& p1, gp_Pnt& p2)
 {
     // they might be the same point
@@ -746,36 +750,71 @@ TopLoc_Location Part::Tools::fromPlacement(const Base::Placement& plm)
     return {trf};
 }
 
-bool Part::Tools::isConcave(const TopoDS_Face &face, const gp_Pnt &pointOfVue, const gp_Dir &direction){
+bool Part::Tools::isConcave(const TopoDS_Face& face,
+                            const gp_Pnt& pointOfVue,
+                            const gp_Dir& direction)
+{
     bool result = false;
 
     Handle(Geom_Surface) surf = BRep_Tool::Surface(face);
     GeomAdaptor_Surface adapt(surf);
-    if(adapt.GetType() == GeomAbs_Plane){
+    if (adapt.GetType() == GeomAbs_Plane) {
         return false;
     }
 
-            // create a line through the point of vue
+    // create a line through the point of vue
     gp_Lin line;
     line.SetLocation(pointOfVue);
     line.SetDirection(direction);
 
-            // Find intersection of line with the face
+    // Find intersection of line with the face
     BRepIntCurveSurface_Inter mkSection;
     mkSection.Init(face, line, Precision::Confusion());
 
     result = mkSection.Transition() == IntCurveSurface_In;
 
-            // compute normals at the intersection
+    // compute normals at the intersection
     gp_Pnt iPnt;
     gp_Vec dU, dV;
     surf->D1(mkSection.U(), mkSection.V(), iPnt, dU, dV);
 
-            // check normals orientation
+    // check normals orientation
     gp_Dir dirdU(dU);
-    result = (dirdU.Angle(direction) - std::numbers::pi/2) <= Precision::Confusion();
+    result = (dirdU.Angle(direction) - std::numbers::pi / 2) <= Precision::Confusion();
     gp_Dir dirdV(dV);
-    result = result || ((dirdV.Angle(direction) - std::numbers::pi/2) <= Precision::Confusion());
+    result = result || ((dirdV.Angle(direction) - std::numbers::pi / 2) <= Precision::Confusion());
 
     return result;
 }
+
+bool Part::Tools::isShapeEmpty(const TopoShape& shape)
+{
+    return shape.isEmpty();
+}
+
+bool Part::Tools::isShapeEmpty(const TopoDS_Shape& shape)
+{
+    static const auto isEveryShapeInCompoundEmpty = [](const TopoDS_Shape& shape) {
+        for (TopoDS_Iterator it(shape); it.More(); it.Next()) {
+            if (const TopoDS_Shape& sub = it.Value(); !isShapeEmpty(sub)) {
+                // Found a non-empty sub-shape
+                return false;
+            }
+        }
+
+        return true;
+    };
+
+    // If shape is null we consider it as empty
+    if (shape.IsNull()) {
+        return true;
+    }
+
+    if (shape.ShapeType() == TopAbs_COMPOUND) {
+        return isEveryShapeInCompoundEmpty(shape);
+    }
+
+    // To see if shape is non-empty we check if it has at least one vertex
+    TopExp_Explorer explorer(shape, TopAbs_VERTEX);
+    return !explorer.More();
+}

src/Mod/Part/App/Tools.h

@@ -43,6 +43,10 @@
 #include <vector>
 
 
+namespace Part
+{
+class TopoShape;
+}
 class gp_Lin;
 class gp_Pln;
 
@@ -235,6 +239,26 @@ public:
      * and false otherwise, plane case included.
      */
     static bool isConcave(const TopoDS_Face &face, const gp_Pnt &pointOfVue, const gp_Dir &direction);
+
+    /**
+     * \copydoc Part::Tools::isShapeEmpty(const TopoDS_Shape&)
+     */
+    static bool isShapeEmpty(const TopoShape& shape);
+
+    /**
+     * \brief Determines whether the given \ref TopoDS_Shape is empty.
+     *
+     * This function evaluates whether a given shape is considered "empty."
+     *
+     * A shape is empty if:
+     * - It is null (uninitialized).
+     * - It is a compound shape (i.e., a container for sub-shapes), but all its sub-shapes are empty.
+     * - It does not have any geometry.
+     *
+     * \param[in] shape The shape to evaluate.
+     * \return `true` if the shape is empty, otherwise `false`.
+     */
+    static bool isShapeEmpty(const TopoDS_Shape& shape);
 };
 
 } //namespace Part

src/Mod/Part/App/TopoShape.cpp

@@ -1361,6 +1361,11 @@ bool TopoShape::isValid() const
     return aChecker.IsValid() ? true : false;
 }
 
+bool TopoShape::isEmpty() const
+{
+    return Tools::isShapeEmpty(this->_Shape);
+}
+
 namespace Part {
 std::vector<std::string> buildShapeEnumVector()
 {

src/Mod/Part/App/TopoShape.h

@@ -487,6 +487,7 @@ public:
     //@{
     bool isNull() const;
     bool isValid() const;
+    bool isEmpty() const;
     bool analyze(bool runBopCheck, std::ostream&) const;
     bool isClosed() const;
     bool isCoplanar(const TopoShape& other, double tol = -1) const;

src/Mod/Part/Gui/AppPartGui.cpp

@@ -68,6 +68,7 @@
 #include "ViewProviderMirror.h"
 #include "ViewProviderPlaneParametric.h"
 #include "ViewProviderPointParametric.h"
+#include "ViewProviderPreviewExtension.h"
 #include "ViewProviderPrism.h"
 #include "ViewProviderProjectOnSurface.h"
 #include "ViewProviderRegularPolygon.h"
@@ -162,10 +163,13 @@ PyMOD_INIT_FUNC(PartGui)
     PartGui::SoBrepEdgeSet                          ::initClass();
     PartGui::SoBrepPointSet                         ::initClass();
     PartGui::SoFCControlPoints                      ::initClass();
+    PartGui::SoPreviewShape                         ::initClass();
     PartGui::ViewProviderAttachExtension            ::init();
     PartGui::ViewProviderAttachExtensionPython      ::init();
     PartGui::ViewProviderGridExtension              ::init();
     PartGui::ViewProviderGridExtensionPython        ::init();
+    PartGui::ViewProviderPreviewExtension           ::init();
+    PartGui::ViewProviderPreviewExtensionPython     ::init();
     PartGui::ViewProviderSplineExtension            ::init();
     PartGui::ViewProviderSplineExtensionPython      ::init();
     PartGui::ViewProviderLine                       ::init();

src/Mod/Part/Gui/CMakeLists.txt

@@ -162,6 +162,8 @@ SET(PartGui_SRCS
     ViewProvider.h
     ViewProviderAttachExtension.h
     ViewProviderAttachExtension.cpp
+    ViewProviderPreviewExtension.h
+    ViewProviderPreviewExtension.cpp
     ViewProviderDatum.cpp
     ViewProviderDatum.h
     ViewProviderExt.cpp

src/Mod/Part/Gui/ViewProviderExt.cpp

@@ -564,7 +564,7 @@ std::vector<Base::Vector3d> ViewProviderPartExt::getModelPoints(const SoPickedPo
     try {
         std::vector<Base::Vector3d> pts;
         std::string element = this->getElement(pp->getDetail());
-        const auto &shape = Part::Feature::getTopoShape(getObject(), Part::ShapeOption::ResolveLink | Part::ShapeOption::Transform);
+        const auto &shape = getRenderedShape();
 
         TopoDS_Shape subShape = shape.getSubShape(element.c_str());
 
@@ -926,6 +926,404 @@ void ViewProviderPartExt::unsetEdit(int ModNum)
     }
 }
 
+void ViewProviderPartExt::setupCoinGeometry(TopoDS_Shape shape,
+                           SoCoordinate3* coords,
+                           SoBrepFaceSet* faceset,
+                           SoNormal* norm,
+                           SoBrepEdgeSet* lineset,
+                           SoBrepPointSet* nodeset,
+                           double deviation,
+                           double angularDeflection,
+                           bool normalsFromUV)
+{
+    if (Part::Tools::isShapeEmpty(shape)) {
+        coords->point.setNum(0);
+        norm->vector.setNum(0);
+        faceset->coordIndex.setNum(0);
+        faceset->partIndex.setNum(0);
+        lineset->coordIndex.setNum(0);
+        nodeset->startIndex.setValue(0);
+        return;
+    }
+
+    // time measurement and book keeping
+    Base::TimeElapsed startTime;
+
+    [[maybe_unused]]
+    int numTriangles = 0, numNodes = 0, numNorms = 0, numFaces = 0, numEdges = 0, numLines = 0;
+
+    std::set<int> faceEdges;
+
+    // calculating the deflection value
+    Bnd_Box bounds;
+    BRepBndLib::Add(shape, bounds);
+    bounds.SetGap(0.0);
+    Standard_Real xMin, yMin, zMin, xMax, yMax, zMax;
+    bounds.Get(xMin, yMin, zMin, xMax, yMax, zMax);
+    Standard_Real deflection = ((xMax - xMin) + (yMax - yMin) + (zMax - zMin)) / 300.0 * deviation;
+
+    // Since OCCT 7.6 a value of equal 0 is not allowed any more, this can happen if a single
+    // vertex should be displayed.
+    if (deflection < gp::Resolution()) {
+        deflection = Precision::Confusion();
+    }
+
+    // For very big objects the computed deflection can become very high and thus leads to a
+    // useless tessellation. To avoid this the upper limit is set to 20.0 See also forum:
+    // https://forum.freecad.org/viewtopic.php?t=77521
+    // deflection = std::min(deflection, 20.0);
+
+    // create or use the mesh on the data structure
+    Standard_Real AngDeflectionRads = Base::toRadians(angularDeflection);
+
+    IMeshTools_Parameters meshParams;
+    meshParams.Deflection = deflection;
+    meshParams.Relative = Standard_False;
+    meshParams.Angle = AngDeflectionRads;
+    meshParams.InParallel = Standard_True;
+    meshParams.AllowQualityDecrease = Standard_True;
+
+    BRepMesh_IncrementalMesh(shape, meshParams);
+
+    // We must reset the location here because the transformation data
+    // are set in the placement property
+    TopLoc_Location aLoc;
+    shape.Location(aLoc);
+
+    // count triangles and nodes in the mesh
+    TopTools_IndexedMapOfShape faceMap;
+    TopExp::MapShapes(shape, TopAbs_FACE, faceMap);
+    for (int i = 1; i <= faceMap.Extent(); i++) {
+        Handle(Poly_Triangulation) mesh = BRep_Tool::Triangulation(TopoDS::Face(faceMap(i)), aLoc);
+
+        if (mesh.IsNull()) {
+            mesh = Part::Tools::triangulationOfFace(TopoDS::Face(faceMap(i)));
+        }
+
+        // Note: we must also count empty faces
+        if (!mesh.IsNull()) {
+            numTriangles += mesh->NbTriangles();
+            numNodes += mesh->NbNodes();
+            numNorms += mesh->NbNodes();
+        }
+
+        TopExp_Explorer xp;
+        for (xp.Init(faceMap(i), TopAbs_EDGE); xp.More(); xp.Next()) {
+            faceEdges.insert(Part::ShapeMapHasher {}(xp.Current()));
+        }
+        numFaces++;
+    }
+
+    // get an indexed map of edges
+    TopTools_IndexedMapOfShape edgeMap;
+    TopExp::MapShapes(shape, TopAbs_EDGE, edgeMap);
+
+    // key is the edge number, value the coord indexes. This is needed to keep the same order as
+    // the edges.
+    std::map<int, std::vector<int32_t>> lineSetMap;
+    std::set<int> edgeIdxSet;
+    std::vector<int32_t> edgeVector;
+
+    // count and index the edges
+    for (int i = 1; i <= edgeMap.Extent(); i++) {
+        edgeIdxSet.insert(i);
+        numEdges++;
+
+        const TopoDS_Edge& aEdge = TopoDS::Edge(edgeMap(i));
+        TopLoc_Location aLoc;
+
+        // handling of the free edge that are not associated to a face
+        // Note: The assumption that if for an edge BRep_Tool::Polygon3D
+        // returns a valid object is wrong. This e.g. happens for ruled
+        // surfaces which gets created by two edges or wires.
+        // So, we have to store the hashes of the edges associated to a face.
+        // If the hash of a given edge is not in this list we know it's really
+        // a free edge.
+        int hash = Part::ShapeMapHasher {}(aEdge);
+        if (faceEdges.find(hash) == faceEdges.end()) {
+            Handle(Poly_Polygon3D) aPoly = Part::Tools::polygonOfEdge(aEdge, aLoc);
+            if (!aPoly.IsNull()) {
+                int nbNodesInEdge = aPoly->NbNodes();
+                numNodes += nbNodesInEdge;
+            }
+        }
+    }
+
+    // handling of the vertices
+    TopTools_IndexedMapOfShape vertexMap;
+    TopExp::MapShapes(shape, TopAbs_VERTEX, vertexMap);
+    numNodes += vertexMap.Extent();
+
+    // create memory for the nodes and indexes
+    coords->point.setNum(numNodes);
+    norm->vector.setNum(numNorms);
+    faceset->coordIndex.setNum(numTriangles * 4);
+    faceset->partIndex.setNum(numFaces);
+
+    // get the raw memory for fast fill up
+    SbVec3f* verts = coords->point.startEditing();
+    SbVec3f* norms = norm->vector.startEditing();
+    int32_t* index = faceset->coordIndex.startEditing();
+    int32_t* parts = faceset->partIndex.startEditing();
+
+    // preset the normal vector with null vector
+    for (int i = 0; i < numNorms; i++) {
+        norms[i] = SbVec3f(0.0, 0.0, 0.0);
+    }
+
+    int ii = 0, faceNodeOffset = 0, faceTriaOffset = 0;
+    for (int i = 1; i <= faceMap.Extent(); i++, ii++) {
+        TopLoc_Location aLoc;
+        const TopoDS_Face& actFace = TopoDS::Face(faceMap(i));
+        // get the mesh of the shape
+        Handle(Poly_Triangulation) mesh = BRep_Tool::Triangulation(actFace, aLoc);
+        if (mesh.IsNull()) {
+            mesh = Part::Tools::triangulationOfFace(actFace);
+        }
+        if (mesh.IsNull()) {
+            parts[ii] = 0;
+            continue;
+        }
+
+        // getting the transformation of the shape/face
+        gp_Trsf myTransf;
+        Standard_Boolean identity = true;
+        if (!aLoc.IsIdentity()) {
+            identity = false;
+            myTransf = aLoc.Transformation();
+        }
+
+        // getting size of node and triangle array of this face
+        int nbNodesInFace = mesh->NbNodes();
+        int nbTriInFace = mesh->NbTriangles();
+        // check orientation
+        TopAbs_Orientation orient = actFace.Orientation();
+
+        // cycling through the poly mesh
+#if OCC_VERSION_HEX < 0x070600
+        const Poly_Array1OfTriangle& Triangles = mesh->Triangles();
+        const TColgp_Array1OfPnt& Nodes = mesh->Nodes();
+        TColgp_Array1OfDir Normals(Nodes.Lower(), Nodes.Upper());
+#else
+        int numNodes = mesh->NbNodes();
+        TColgp_Array1OfDir Normals(1, numNodes);
+#endif
+        if (normalsFromUV) {
+            Part::Tools::getPointNormals(actFace, mesh, Normals);
+        }
+
+        for (int g = 1; g <= nbTriInFace; g++) {
+            // Get the triangle
+            Standard_Integer N1, N2, N3;
+#if OCC_VERSION_HEX < 0x070600
+            Triangles(g).Get(N1, N2, N3);
+#else
+            mesh->Triangle(g).Get(N1, N2, N3);
+#endif
+
+            // change orientation of the triangle if the face is reversed
+            if (orient != TopAbs_FORWARD) {
+                Standard_Integer tmp = N1;
+                N1 = N2;
+                N2 = tmp;
+            }
+
+            // get the 3 points of this triangle
+#if OCC_VERSION_HEX < 0x070600
+            gp_Pnt V1(Nodes(N1)), V2(Nodes(N2)), V3(Nodes(N3));
+#else
+            gp_Pnt V1(mesh->Node(N1)), V2(mesh->Node(N2)), V3(mesh->Node(N3));
+#endif
+
+            // get the 3 normals of this triangle
+            gp_Vec NV1, NV2, NV3;
+            if (normalsFromUV) {
+                NV1.SetXYZ(Normals(N1).XYZ());
+                NV2.SetXYZ(Normals(N2).XYZ());
+                NV3.SetXYZ(Normals(N3).XYZ());
+            }
+            else {
+                gp_Vec v1(V1.X(), V1.Y(), V1.Z()),
+                       v2(V2.X(), V2.Y(), V2.Z()),
+                       v3(V3.X(), V3.Y(), V3.Z());
+
+                gp_Vec normal = (v2 - v1) ^ (v3 - v1);
+                NV1 = normal;
+                NV2 = normal;
+                NV3 = normal;
+            }
+
+            // transform the vertices and normals to the place of the face
+            if (!identity) {
+                V1.Transform(myTransf);
+                V2.Transform(myTransf);
+                V3.Transform(myTransf);
+                if (normalsFromUV) {
+                    NV1.Transform(myTransf);
+                    NV2.Transform(myTransf);
+                    NV3.Transform(myTransf);
+                }
+            }
+
+            // add the normals for all points of this triangle
+            norms[faceNodeOffset + N1 - 1] += SbVec3f(NV1.X(), NV1.Y(), NV1.Z());
+            norms[faceNodeOffset + N2 - 1] += SbVec3f(NV2.X(), NV2.Y(), NV2.Z());
+            norms[faceNodeOffset + N3 - 1] += SbVec3f(NV3.X(), NV3.Y(), NV3.Z());
+
+            // set the vertices
+            verts[faceNodeOffset + N1 - 1].setValue((float)(V1.X()),
+                                                    (float)(V1.Y()),
+                                                    (float)(V1.Z()));
+            verts[faceNodeOffset + N2 - 1].setValue((float)(V2.X()),
+                                                    (float)(V2.Y()),
+                                                    (float)(V2.Z()));
+            verts[faceNodeOffset + N3 - 1].setValue((float)(V3.X()),
+                                                    (float)(V3.Y()),
+                                                    (float)(V3.Z()));
+
+            // set the index vector with the 3 point indexes and the end delimiter
+            index[faceTriaOffset * 4 + 4 * (g - 1)]     = faceNodeOffset + N1 - 1;
+            index[faceTriaOffset * 4 + 4 * (g - 1) + 1] = faceNodeOffset + N2 - 1;
+            index[faceTriaOffset * 4 + 4 * (g - 1) + 2] = faceNodeOffset + N3 - 1;
+            index[faceTriaOffset * 4 + 4 * (g - 1) + 3] = SO_END_FACE_INDEX;
+        }
+
+        parts[ii] = nbTriInFace;  // new part
+
+        // handling the edges lying on this face
+        TopExp_Explorer Exp;
+        for (Exp.Init(actFace, TopAbs_EDGE); Exp.More(); Exp.Next()) {
+            const TopoDS_Edge& curEdge = TopoDS::Edge(Exp.Current());
+            // get the overall index of this edge
+            int edgeIndex = edgeMap.FindIndex(curEdge);
+            edgeVector.push_back((int32_t)edgeIndex - 1);
+            // already processed this index ?
+            if (edgeIdxSet.find(edgeIndex) != edgeIdxSet.end()) {
+
+                // this holds the indices of the edge's triangulation to the current polygon
+                Handle(Poly_PolygonOnTriangulation) aPoly =
+                    BRep_Tool::PolygonOnTriangulation(curEdge, mesh, aLoc);
+                if (aPoly.IsNull()) {
+                    continue;  // polygon does not exist
+                }
+
+                // getting the indexes of the edge polygon
+                const TColStd_Array1OfInteger& indices = aPoly->Nodes();
+                for (Standard_Integer i = indices.Lower(); i <= indices.Upper(); i++) {
+                    int nodeIndex = indices(i);
+                    int index = faceNodeOffset + nodeIndex - 1;
+                    lineSetMap[edgeIndex].push_back(index);
+
+                    // usually the coordinates for this edge are already set by the
+                    // triangles of the face this edge belongs to. However, there are
+                    // rare cases where some points are only referenced by the polygon
+                    // but not by any triangle. Thus, we must apply the coordinates to
+                    // make sure that everything is properly set.
+#if OCC_VERSION_HEX < 0x070600
+                    gp_Pnt p(Nodes(nodeIndex));
+#else
+                    gp_Pnt p(mesh->Node(nodeIndex));
+#endif
+                    if (!identity) {
+                        p.Transform(myTransf);
+                    }
+                    verts[index].setValue((float)(p.X()), (float)(p.Y()), (float)(p.Z()));
+                }
+
+                // remove the handled edge index from the set
+                edgeIdxSet.erase(edgeIndex);
+            }
+        }
+
+        edgeVector.push_back(-1);
+
+        // counting up the per Face offsets
+        faceNodeOffset += nbNodesInFace;
+        faceTriaOffset += nbTriInFace;
+    }
+
+    // handling of the free edges
+    for (int i = 1; i <= edgeMap.Extent(); i++) {
+        const TopoDS_Edge& aEdge = TopoDS::Edge(edgeMap(i));
+        Standard_Boolean identity = true;
+        gp_Trsf myTransf;
+        TopLoc_Location aLoc;
+
+        // handling of the free edge that are not associated to a face
+        int hash = Part::ShapeMapHasher {}(aEdge);
+        if (faceEdges.find(hash) == faceEdges.end()) {
+            Handle(Poly_Polygon3D) aPoly = Part::Tools::polygonOfEdge(aEdge, aLoc);
+            if (!aPoly.IsNull()) {
+                if (!aLoc.IsIdentity()) {
+                    identity = false;
+                    myTransf = aLoc.Transformation();
+                }
+
+                const TColgp_Array1OfPnt& aNodes = aPoly->Nodes();
+                int nbNodesInEdge = aPoly->NbNodes();
+
+                gp_Pnt pnt;
+                for (Standard_Integer j = 1; j <= nbNodesInEdge; j++) {
+                    pnt = aNodes(j);
+                    if (!identity) {
+                        pnt.Transform(myTransf);
+                    }
+                    int index = faceNodeOffset + j - 1;
+                    verts[index].setValue((float)(pnt.X()), (float)(pnt.Y()), (float)(pnt.Z()));
+                    lineSetMap[i].push_back(index);
+                }
+
+                faceNodeOffset += nbNodesInEdge;
+            }
+        }
+    }
+
+    nodeset->startIndex.setValue(faceNodeOffset);
+    for (int i = 0; i < vertexMap.Extent(); i++) {
+        const TopoDS_Vertex& aVertex = TopoDS::Vertex(vertexMap(i + 1));
+        gp_Pnt pnt = BRep_Tool::Pnt(aVertex);
+        verts[faceNodeOffset + i].setValue((float)(pnt.X()),
+                                           (float)(pnt.Y()),
+                                           (float)(pnt.Z()));
+    }
+
+    // normalize all normals
+    for (int i = 0; i < numNorms; i++) {
+        norms[i].normalize();
+    }
+
+    std::vector<int32_t> lineSetCoords;
+    for (const auto& it : lineSetMap) {
+        lineSetCoords.insert(lineSetCoords.end(), it.second.begin(), it.second.end());
+        lineSetCoords.push_back(-1);
+    }
+
+    // preset the index vector size
+    numLines = lineSetCoords.size();
+    lineset->coordIndex.setNum(numLines);
+    int32_t* lines = lineset->coordIndex.startEditing();
+
+    int l = 0;
+    for (std::vector<int32_t>::const_iterator it = lineSetCoords.begin();
+         it != lineSetCoords.end();
+         ++it, l++) {
+        lines[l] = *it;
+    }
+
+    // end the editing of the nodes
+    coords->point.finishEditing();
+    norm->vector.finishEditing();
+    faceset->coordIndex.finishEditing();
+    faceset->partIndex.finishEditing();
+    lineset->coordIndex.finishEditing();
+
+#   ifdef FC_DEBUG
+    // printing some information
+    Base::Console().log("ViewProvider update time: %f s\n",Base::TimeElapsed::diffTimeF(startTime,Base::TimeElapsed()));
+    Base::Console().log("Shape tria info: Faces:%d Edges:%d Nodes:%d Triangles:%d IdxVec:%d\n",numFaces,numEdges,numNodes,numTriangles,numLines);
+#   endif
+}
+
 void ViewProviderPartExt::updateVisual()
 {
     Gui::SoUpdateVBOAction action;
@@ -943,382 +1341,30 @@ void ViewProviderPartExt::updateVisual()
     haction.apply(this->lineset);
     haction.apply(this->nodeset);
 
-    TopoDS_Shape cShape = Part::Feature::getShape(getObject(), Part::ShapeOption::ResolveLink | Part::ShapeOption::Transform);
-    if (cShape.IsNull()) {
-        coords  ->point      .setNum(0);
-        norm    ->vector     .setNum(0);
-        faceset ->coordIndex .setNum(0);
-        faceset ->partIndex  .setNum(0);
-        lineset ->coordIndex .setNum(0);
-        nodeset ->startIndex .setValue(0);
-        VisualTouched = false;
-        return;
-    }
-
-    // time measurement and book keeping
-    Base::TimeElapsed start_time;
-    int numTriangles=0,numNodes=0,numNorms=0,numFaces=0,numEdges=0,numLines=0;
-    std::set<int> faceEdges;
-
     try {
-        // calculating the deflection value
-        Bnd_Box bounds;
-        BRepBndLib::Add(cShape, bounds);
-        bounds.SetGap(0.0);
-        Standard_Real xMin, yMin, zMin, xMax, yMax, zMax;
-        bounds.Get(xMin, yMin, zMin, xMax, yMax, zMax);
-        Standard_Real deflection = ((xMax-xMin)+(yMax-yMin)+(zMax-zMin))/300.0 * Deviation.getValue();
+        TopoDS_Shape cShape = getRenderedShape().getShape();
 
-        // Since OCCT 7.6 a value of equal 0 is not allowed any more, this can happen if a single vertex
-        // should be displayed.
-        if (deflection < gp::Resolution()) {
-            deflection = Precision::Confusion();
-        }
+        setupCoinGeometry(cShape,
+                          coords,
+                          faceset,
+                          norm,
+                          lineset,
+                          nodeset,
+                          Deviation.getValue(),
+                          AngularDeflection.getValue(),
+                          NormalsFromUV);
 
-        // For very big objects the computed deflection can become very high and thus leads to a useless
-        // tessellation. To avoid this the upper limit is set to 20.0
-        // See also forum: https://forum.freecad.org/viewtopic.php?t=77521
-        //deflection = std::min(deflection, 20.0);
-
-        // create or use the mesh on the data structure
-        Standard_Real AngDeflectionRads = Base::toRadians(AngularDeflection.getValue());
-
-        IMeshTools_Parameters meshParams;
-        meshParams.Deflection = deflection;
-        meshParams.Relative = Standard_False;
-        meshParams.Angle = AngDeflectionRads;
-        meshParams.InParallel = Standard_True;
-        meshParams.AllowQualityDecrease = Standard_True;
-
-        BRepMesh_IncrementalMesh(cShape, meshParams);
-
-        // We must reset the location here because the transformation data
-        // are set in the placement property
-        TopLoc_Location aLoc;
-        cShape.Location(aLoc);
-
-        // count triangles and nodes in the mesh
-        TopTools_IndexedMapOfShape faceMap;
-        TopExp::MapShapes(cShape, TopAbs_FACE, faceMap);
-        for (int i=1; i <= faceMap.Extent(); i++) {
-            Handle (Poly_Triangulation) mesh = BRep_Tool::Triangulation(TopoDS::Face(faceMap(i)), aLoc);
-            if (mesh.IsNull()) {
-                mesh = Part::Tools::triangulationOfFace(TopoDS::Face(faceMap(i)));
-            }
-            // Note: we must also count empty faces
-            if (!mesh.IsNull()) {
-                numTriangles += mesh->NbTriangles();
-                numNodes     += mesh->NbNodes();
-                numNorms     += mesh->NbNodes();
-            }
-
-            TopExp_Explorer xp;
-            for (xp.Init(faceMap(i),TopAbs_EDGE);xp.More();xp.Next()) {
-                faceEdges.insert(Part::ShapeMapHasher{}(xp.Current()));
-            }
-            numFaces++;
-        }
-
-        // get an indexed map of edges
-        TopTools_IndexedMapOfShape edgeMap;
-        TopExp::MapShapes(cShape, TopAbs_EDGE, edgeMap);
-
-         // key is the edge number, value the coord indexes. This is needed to keep the same order as the edges.
-        std::map<int, std::vector<int32_t> > lineSetMap;
-        std::set<int>          edgeIdxSet;
-        std::vector<int32_t>   edgeVector;
-
-        // count and index the edges
-        for (int i=1; i <= edgeMap.Extent(); i++) {
-            edgeIdxSet.insert(i);
-            numEdges++;
-
-            const TopoDS_Edge& aEdge = TopoDS::Edge(edgeMap(i));
-            TopLoc_Location aLoc;
-
-            // handling of the free edge that are not associated to a face
-            // Note: The assumption that if for an edge BRep_Tool::Polygon3D
-            // returns a valid object is wrong. This e.g. happens for ruled
-            // surfaces which gets created by two edges or wires.
-            // So, we have to store the hashes of the edges associated to a face.
-            // If the hash of a given edge is not in this list we know it's really
-            // a free edge.
-            int hash = Part::ShapeMapHasher{}(aEdge);
-            if (faceEdges.find(hash) == faceEdges.end()) {
-                Handle(Poly_Polygon3D) aPoly = Part::Tools::polygonOfEdge(aEdge, aLoc);
-                if (!aPoly.IsNull()) {
-                    int nbNodesInEdge = aPoly->NbNodes();
-                    numNodes += nbNodesInEdge;
-                }
-            }
-        }
-
-        // handling of the vertices
-        TopTools_IndexedMapOfShape vertexMap;
-        TopExp::MapShapes(cShape, TopAbs_VERTEX, vertexMap);
-        numNodes += vertexMap.Extent();
-
-        // create memory for the nodes and indexes
-        coords  ->point      .setNum(numNodes);
-        norm    ->vector     .setNum(numNorms);
-        faceset ->coordIndex .setNum(numTriangles*4);
-        faceset ->partIndex  .setNum(numFaces);
-        // get the raw memory for fast fill up
-        SbVec3f* verts = coords  ->point       .startEditing();
-        SbVec3f* norms = norm    ->vector      .startEditing();
-        int32_t* index = faceset ->coordIndex  .startEditing();
-        int32_t* parts = faceset ->partIndex   .startEditing();
-
-        // preset the normal vector with null vector
-        for (int i=0;i < numNorms;i++)
-            norms[i]= SbVec3f(0.0,0.0,0.0);
-
-        int ii = 0,faceNodeOffset=0,faceTriaOffset=0;
-        for (int i=1; i <= faceMap.Extent(); i++, ii++) {
-            TopLoc_Location aLoc;
-            const TopoDS_Face &actFace = TopoDS::Face(faceMap(i));
-            // get the mesh of the shape
-            Handle (Poly_Triangulation) mesh = BRep_Tool::Triangulation(actFace,aLoc);
-            if (mesh.IsNull()) {
-                mesh = Part::Tools::triangulationOfFace(actFace);
-            }
-            if (mesh.IsNull()) {
-                parts[ii] = 0;
-                continue;
-            }
-
-            // getting the transformation of the shape/face
-            gp_Trsf myTransf;
-            Standard_Boolean identity = true;
-            if (!aLoc.IsIdentity()) {
-                identity = false;
-                myTransf = aLoc.Transformation();
-            }
-
-            // getting size of node and triangle array of this face
-            int nbNodesInFace = mesh->NbNodes();
-            int nbTriInFace   = mesh->NbTriangles();
-            // check orientation
-            TopAbs_Orientation orient = actFace.Orientation();
-
-
-            // cycling through the poly mesh
-#if OCC_VERSION_HEX < 0x070600
-            const Poly_Array1OfTriangle& Triangles = mesh->Triangles();
-            const TColgp_Array1OfPnt& Nodes = mesh->Nodes();
-            TColgp_Array1OfDir Normals (Nodes.Lower(), Nodes.Upper());
-#else
-            int numNodes =  mesh->NbNodes();
-            TColgp_Array1OfDir Normals (1, numNodes);
-#endif
-            if (NormalsFromUV)
-                Part::Tools::getPointNormals(actFace, mesh, Normals);
-
-            for (int g=1;g<=nbTriInFace;g++) {
-                // Get the triangle
-                Standard_Integer N1,N2,N3;
-#if OCC_VERSION_HEX < 0x070600
-                Triangles(g).Get(N1,N2,N3);
-#else
-                mesh->Triangle(g).Get(N1,N2,N3);
-#endif
-
-                // change orientation of the triangle if the face is reversed
-                if ( orient != TopAbs_FORWARD ) {
-                    Standard_Integer tmp = N1;
-                    N1 = N2;
-                    N2 = tmp;
-                }
-
-                // get the 3 points of this triangle
-#if OCC_VERSION_HEX < 0x070600
-                gp_Pnt V1(Nodes(N1)), V2(Nodes(N2)), V3(Nodes(N3));
-#else
-                gp_Pnt V1(mesh->Node(N1)), V2(mesh->Node(N2)), V3(mesh->Node(N3));
-#endif
-
-                // get the 3 normals of this triangle
-                gp_Vec NV1, NV2, NV3;
-                if (NormalsFromUV) {
-                    NV1.SetXYZ(Normals(N1).XYZ());
-                    NV2.SetXYZ(Normals(N2).XYZ());
-                    NV3.SetXYZ(Normals(N3).XYZ());
-                }
-                else {
-                    gp_Vec v1(V1.X(),V1.Y(),V1.Z()),
-                           v2(V2.X(),V2.Y(),V2.Z()),
-                           v3(V3.X(),V3.Y(),V3.Z());
-                    gp_Vec normal = (v2-v1)^(v3-v1);
-                    NV1 = normal;
-                    NV2 = normal;
-                    NV3 = normal;
-                }
-
-                // transform the vertices and normals to the place of the face
-                if (!identity) {
-                    V1.Transform(myTransf);
-                    V2.Transform(myTransf);
-                    V3.Transform(myTransf);
-                    if (NormalsFromUV) {
-                        NV1.Transform(myTransf);
-                        NV2.Transform(myTransf);
-                        NV3.Transform(myTransf);
-                    }
-                }
-
-                // add the normals for all points of this triangle
-                norms[faceNodeOffset+N1-1] += SbVec3f(NV1.X(),NV1.Y(),NV1.Z());
-                norms[faceNodeOffset+N2-1] += SbVec3f(NV2.X(),NV2.Y(),NV2.Z());
-                norms[faceNodeOffset+N3-1] += SbVec3f(NV3.X(),NV3.Y(),NV3.Z());
-
-                // set the vertices
-                verts[faceNodeOffset+N1-1].setValue((float)(V1.X()),(float)(V1.Y()),(float)(V1.Z()));
-                verts[faceNodeOffset+N2-1].setValue((float)(V2.X()),(float)(V2.Y()),(float)(V2.Z()));
-                verts[faceNodeOffset+N3-1].setValue((float)(V3.X()),(float)(V3.Y()),(float)(V3.Z()));
-
-                // set the index vector with the 3 point indexes and the end delimiter
-                index[faceTriaOffset*4+4*(g-1)]   = faceNodeOffset+N1-1;
-                index[faceTriaOffset*4+4*(g-1)+1] = faceNodeOffset+N2-1;
-                index[faceTriaOffset*4+4*(g-1)+2] = faceNodeOffset+N3-1;
-                index[faceTriaOffset*4+4*(g-1)+3] = SO_END_FACE_INDEX;
-            }
-
-            parts[ii] = nbTriInFace; // new part
-
-            // handling the edges lying on this face
-            TopExp_Explorer Exp;
-            for(Exp.Init(actFace,TopAbs_EDGE);Exp.More();Exp.Next()) {
-                const TopoDS_Edge &curEdge = TopoDS::Edge(Exp.Current());
-                // get the overall index of this edge
-                int edgeIndex = edgeMap.FindIndex(curEdge);
-                edgeVector.push_back((int32_t)edgeIndex-1);
-                // already processed this index ?
-                if (edgeIdxSet.find(edgeIndex)!=edgeIdxSet.end()) {
-
-                    // this holds the indices of the edge's triangulation to the current polygon
-                    Handle(Poly_PolygonOnTriangulation) aPoly = BRep_Tool::PolygonOnTriangulation(curEdge, mesh, aLoc);
-                    if (aPoly.IsNull())
-                        continue; // polygon does not exist
-
-                    // getting the indexes of the edge polygon
-                    const TColStd_Array1OfInteger& indices = aPoly->Nodes();
-                    for (Standard_Integer i=indices.Lower();i <= indices.Upper();i++) {
-                        int nodeIndex = indices(i);
-                        int index = faceNodeOffset+nodeIndex-1;
-                        lineSetMap[edgeIndex].push_back(index);
-
-                        // usually the coordinates for this edge are already set by the
-                        // triangles of the face this edge belongs to. However, there are
-                        // rare cases where some points are only referenced by the polygon
-                        // but not by any triangle. Thus, we must apply the coordinates to
-                        // make sure that everything is properly set.
-#if OCC_VERSION_HEX < 0x070600
-                        gp_Pnt p(Nodes(nodeIndex));
-#else
-                        gp_Pnt p(mesh->Node(nodeIndex));
-#endif
-                        if (!identity)
-                            p.Transform(myTransf);
-                        verts[index].setValue((float)(p.X()),(float)(p.Y()),(float)(p.Z()));
-                    }
-
-                    // remove the handled edge index from the set
-                    edgeIdxSet.erase(edgeIndex);
-                }
-            }
-
-            edgeVector.push_back(-1);
-
-            // counting up the per Face offsets
-            faceNodeOffset += nbNodesInFace;
-            faceTriaOffset += nbTriInFace;
-        }
-
-        // handling of the free edges
-        for (int i=1; i <= edgeMap.Extent(); i++) {
-            const TopoDS_Edge& aEdge = TopoDS::Edge(edgeMap(i));
-            Standard_Boolean identity = true;
-            gp_Trsf myTransf;
-            TopLoc_Location aLoc;
-
-            // handling of the free edge that are not associated to a face
-            int hash = Part::ShapeMapHasher{}(aEdge);
-            if (faceEdges.find(hash) == faceEdges.end()) {
-                Handle(Poly_Polygon3D) aPoly = Part::Tools::polygonOfEdge(aEdge, aLoc);
-                if (!aPoly.IsNull()) {
-                    if (!aLoc.IsIdentity()) {
-                        identity = false;
-                        myTransf = aLoc.Transformation();
-                    }
-
-                    const TColgp_Array1OfPnt& aNodes = aPoly->Nodes();
-                    int nbNodesInEdge = aPoly->NbNodes();
-
-                    gp_Pnt pnt;
-                    for (Standard_Integer j=1;j <= nbNodesInEdge;j++) {
-                        pnt = aNodes(j);
-                        if (!identity)
-                            pnt.Transform(myTransf);
-                        int index = faceNodeOffset+j-1;
-                        verts[index].setValue((float)(pnt.X()),(float)(pnt.Y()),(float)(pnt.Z()));
-                        lineSetMap[i].push_back(index);
-                    }
-
-                    faceNodeOffset += nbNodesInEdge;
-                }
-            }
-        }
-
-        nodeset->startIndex.setValue(faceNodeOffset);
-        for (int i=0; i<vertexMap.Extent(); i++) {
-            const TopoDS_Vertex& aVertex = TopoDS::Vertex(vertexMap(i+1));
-            gp_Pnt pnt = BRep_Tool::Pnt(aVertex);
-            verts[faceNodeOffset+i].setValue((float)(pnt.X()),(float)(pnt.Y()),(float)(pnt.Z()));
-        }
-
-        // normalize all normals
-        for (int i = 0; i< numNorms ;i++)
-            norms[i].normalize();
-
-        std::vector<int32_t> lineSetCoords;
-        for (const auto & it : lineSetMap) {
-            lineSetCoords.insert(lineSetCoords.end(), it.second.begin(), it.second.end());
-            lineSetCoords.push_back(-1);
-        }
-
-        // preset the index vector size
-        numLines =  lineSetCoords.size();
-        lineset ->coordIndex .setNum(numLines);
-        int32_t* lines = lineset ->coordIndex  .startEditing();
-
-        int l=0;
-        for (std::vector<int32_t>::const_iterator it=lineSetCoords.begin();it!=lineSetCoords.end();++it,l++)
-            lines[l] = *it;
-
-        // end the editing of the nodes
-        coords  ->point       .finishEditing();
-        norm    ->vector      .finishEditing();
-        faceset ->coordIndex  .finishEditing();
-        faceset ->partIndex   .finishEditing();
-        lineset ->coordIndex  .finishEditing();
+        VisualTouched = false;
     }
     catch (const Standard_Failure& e) {
         FC_ERR("Cannot compute Inventor representation for the shape of "
                << pcObject->getFullName() << ": " << e.GetMessageString());
     }
     catch (...) {
-        FC_ERR("Cannot compute Inventor representation for the shape of " << pcObject->getFullName());
+        FC_ERR("Cannot compute Inventor representation for the shape of "
+               << pcObject->getFullName());
     }
 
-#   ifdef FC_DEBUG
-        // printing some information
-        Base::Console().log("ViewProvider update time: %f s\n",Base::TimeElapsed::diffTimeF(start_time,Base::TimeElapsed()));
-        Base::Console().log("Shape tria info: Faces:%d Edges:%d Nodes:%d Triangles:%d IdxVec:%d\n",numFaces,numEdges,numNodes,numTriangles,numLines);
-#   else
-    (void)numEdges;
-#   endif
-    VisualTouched = false;
-
     // The material has to be checked again
     setHighlightedFaces(ShapeAppearance.getValues());
     setHighlightedEdges(LineColorArray.getValues());

src/Mod/Part/Gui/ViewProviderExt.h

@@ -123,6 +123,10 @@ public:
     std::vector<Base::Vector3d> getSelectionShape(const char* Element) const override;
     //@}
 
+    virtual Part::TopoShape getRenderedShape() const {
+        return Part::Feature::getTopoShape(getObject(), Part::ShapeOption::ResolveLink | Part::ShapeOption::Transform);
+    }
+
     /** @name Highlight handling
     * This group of methods do the highlighting of elements.
     */
@@ -156,6 +160,17 @@ public:
     /// Get the python wrapper for that ViewProvider
     PyObject* getPyObject() override;
 
+    /// configures Coin nodes so they render given toposhape
+    static void setupCoinGeometry(TopoDS_Shape shape,
+                                  SoCoordinate3* coords,
+                                  SoBrepFaceSet* faceset,
+                                  SoNormal* norm,
+                                  SoBrepEdgeSet* lineset,
+                                  SoBrepPointSet* nodeset,
+                                  double deviation,
+                                  double angularDeflection,
+                                  bool normalsFromUV);
+
 protected:
     bool setEdit(int ModNum) override;
     void unsetEdit(int ModNum) override;

src/Mod/Part/Gui/ViewProviderPreviewExtension.cpp

@@ -0,0 +1,197 @@
+// SPDX-License-Identifier: LGPL-2.1-or-later
+/****************************************************************************
+ *                                                                          *
+ *   Copyright (c) 2025 Kacper Donat <kacper@kadet.net>                     *
+ *                                                                          *
+ *   This file is part of FreeCAD.                                          *
+ *                                                                          *
+ *   FreeCAD is free software: you can redistribute it and/or modify it     *
+ *   under the terms of the GNU Lesser General Public License as            *
+ *   published by the Free Software Foundation, either version 2.1 of the   *
+ *   License, or (at your option) any later version.                        *
+ *                                                                          *
+ *   FreeCAD 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       *
+ *   Lesser General Public License for more details.                        *
+ *                                                                          *
+ *   You should have received a copy of the GNU Lesser General Public       *
+ *   License along with FreeCAD. If not, see                                *
+ *   <https://www.gnu.org/licenses/>.                                       *
+ *                                                                          *
+ ***************************************************************************/
+
+#include "PreCompiled.h"
+
+#ifndef _PreComp_
+# include <Inventor/nodes/SoDrawStyle.h>
+# include <Inventor/nodes/SoLightModel.h>
+# include <Inventor/nodes/SoMaterial.h>
+# include <Inventor/nodes/SoPickStyle.h>
+# include <Inventor/nodes/SoPolygonOffset.h>
+#endif
+
+#include "ViewProviderPreviewExtension.h"
+#include "ViewProviderExt.h"
+
+#include <Gui/Utilities.h>
+#include <Gui/Inventor/So3DAnnotation.h>
+#include <Mod/Part/App/Tools.h>
+
+using namespace PartGui;
+
+SO_NODE_SOURCE(SoPreviewShape);
+
+const SbColor SoPreviewShape::defaultColor = SbColor(1.F, 0.F, 1.F);
+
+SoPreviewShape::SoPreviewShape()
+    : coords(new SoCoordinate3)
+    , norm(new SoNormal)
+    , faceset(new PartGui::SoBrepFaceSet)
+    , lineset(new PartGui::SoBrepEdgeSet)
+    , nodeset(new PartGui::SoBrepPointSet)
+{
+    SO_NODE_CONSTRUCTOR(SoPreviewShape);
+
+    SO_NODE_ADD_FIELD(color, (defaultColor));
+    SO_NODE_ADD_FIELD(transparency, (defaultTransparency));
+    SO_NODE_ADD_FIELD(lineWidth, (defaultLineWidth));
+
+    auto pickStyle = new SoPickStyle;
+    pickStyle->style = SoPickStyle::UNPICKABLE;
+
+    auto* solidLineStyle = new SoDrawStyle();
+    solidLineStyle->lineWidth.connectFrom(&lineWidth);
+
+    auto* hiddenLineStyle = new SoDrawStyle();
+    hiddenLineStyle->lineWidth.connectFrom(&lineWidth);
+    hiddenLineStyle->linePattern = 0xF0F0;
+
+    auto* solidColorLightModel = new SoLightModel();
+    solidColorLightModel->model = SoLightModel::BASE_COLOR;
+
+    auto* normalBinding = new SoNormalBinding();
+    normalBinding->value = SoNormalBinding::PER_VERTEX_INDEXED;
+
+    // This should be OVERALL but then line pattern does not work correctly
+    // Probably a bug in coin to be investigated.
+    auto* materialBinding = new SoMaterialBinding();
+    materialBinding->value = SoMaterialBinding::PER_FACE_INDEXED;
+
+    auto* material = new SoMaterial;
+    material->diffuseColor.connectFrom(&color);
+    material->transparency.connectFrom(&transparency);
+
+    auto* polygonOffset = new SoPolygonOffset;
+    polygonOffset->factor = -0.00001F;
+    polygonOffset->units = -1.0F;
+    polygonOffset->on = true;
+    polygonOffset->styles = SoPolygonOffset::FILLED;
+
+    auto* lineMaterial = new SoMaterial;
+    lineMaterial->diffuseColor.connectFrom(&color);
+    lineMaterial->transparency = 0.0f;
+
+    auto* lineSep = new SoSeparator;
+    lineSep->addChild(normalBinding);
+    lineSep->addChild(materialBinding);
+    lineSep->addChild(solidColorLightModel);
+    lineSep->addChild(lineMaterial);
+    lineSep->addChild(lineset);
+
+    auto* annotation = new Gui::So3DAnnotation;
+    annotation->addChild(hiddenLineStyle);
+    annotation->addChild(material);
+    annotation->addChild(lineSep);
+    annotation->addChild(polygonOffset);
+    annotation->addChild(faceset);
+
+    SoSeparator::addChild(pickStyle);
+    SoSeparator::addChild(solidLineStyle);
+    SoSeparator::addChild(material);
+    SoSeparator::addChild(coords);
+    SoSeparator::addChild(norm);
+    SoSeparator::addChild(lineSep);
+    SoSeparator::addChild(polygonOffset);
+    SoSeparator::addChild(faceset);
+    SoSeparator::addChild(annotation);
+}
+
+EXTENSION_PROPERTY_SOURCE(PartGui::ViewProviderPreviewExtension, Gui::ViewProviderExtension)
+
+ViewProviderPreviewExtension::ViewProviderPreviewExtension()
+{
+    const Base::Color magenta(1.0F, 0.0F, 1.0F);
+
+    EXTENSION_ADD_PROPERTY_TYPE(
+        PreviewColor,
+        (magenta),
+        "Preview",
+        static_cast<App::PropertyType>(App::Prop_Transient | App::Prop_Hidden),
+        "Color used for 3D Preview");
+
+    initExtensionType(ViewProviderPreviewExtension::getExtensionClassTypeId());
+}
+
+void ViewProviderPreviewExtension::extensionAttach(App::DocumentObject* documentObject)
+{
+    ViewProviderExtension::extensionAttach(documentObject);
+
+    pcPreviewShape = new SoPreviewShape;
+
+    pcPreviewRoot = new SoSeparator;
+    pcPreviewRoot->addChild(pcPreviewShape);
+
+    updatePreviewShape();
+}
+void ViewProviderPreviewExtension::extensionOnChanged(const App::Property* prop)
+{
+    if (prop == &PreviewColor) {
+        pcPreviewShape->color.setValue(Base::convertTo<SbColor>(PreviewColor.getValue()));
+    }
+
+    ViewProviderExtension::extensionOnChanged(prop);
+}
+
+void ViewProviderPreviewExtension::updatePreviewShape()
+{
+    auto vp = freecad_cast<ViewProviderPartExt*>(getExtendedViewProvider());
+
+    if (!vp) {
+        return;
+    }
+
+    ViewProviderPartExt::setupCoinGeometry(getPreviewShape().getShape(),
+                                           pcPreviewShape->coords,
+                                           pcPreviewShape->faceset,
+                                           pcPreviewShape->norm,
+                                           pcPreviewShape->lineset,
+                                           pcPreviewShape->nodeset,
+                                           vp->Deviation.getValue(),
+                                           vp->AngularDeflection.getValue(),
+                                           false);
+
+    // For some reason line patterns are not rendered correctly if material binding is set to
+    // anything other than PER_FACE. PER_FACE material binding seems to require materialIndex per
+    // each distinct edge. Until that is fixed, this code forces each edge to use the first material.
+    unsigned lineCoordsCount = pcPreviewShape->lineset->coordIndex.getNum();
+    unsigned lineCount = 1;
+
+    for (unsigned i = 0; i < lineCoordsCount; ++i) {
+        if (pcPreviewShape->lineset->coordIndex[i] < 0) {
+            lineCount++;
+        }
+    }
+
+    pcPreviewShape->lineset->materialIndex.setNum(lineCount);
+    for (unsigned i = 0; i < lineCount; ++i) {
+        pcPreviewShape->lineset->materialIndex.set1Value(i, 0);
+    }
+}
+
+namespace Gui {
+EXTENSION_PROPERTY_SOURCE_TEMPLATE(PartGui::ViewProviderPreviewExtensionPython, PartGui::ViewProviderPreviewExtension)
+
+// explicit template instantiation
+template class PartGuiExport ViewProviderExtensionPythonT<PartGui::ViewProviderPreviewExtension>;
+}

src/Mod/Part/Gui/ViewProviderPreviewExtension.h

@@ -0,0 +1,110 @@
+// SPDX-License-Identifier: LGPL-2.1-or-later
+/****************************************************************************
+ *                                                                          *
+ *   Copyright (c) 2025 Kacper Donat <kacper@kadet.net>                     *
+ *                                                                          *
+ *   This file is part of FreeCAD.                                          *
+ *                                                                          *
+ *   FreeCAD is free software: you can redistribute it and/or modify it     *
+ *   under the terms of the GNU Lesser General Public License as            *
+ *   published by the Free Software Foundation, either version 2.1 of the   *
+ *   License, or (at your option) any later version.                        *
+ *                                                                          *
+ *   FreeCAD 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       *
+ *   Lesser General Public License for more details.                        *
+ *                                                                          *
+ *   You should have received a copy of the GNU Lesser General Public       *
+ *   License along with FreeCAD. If not, see                                *
+ *   <https://www.gnu.org/licenses/>.                                       *
+ *                                                                          *
+ ***************************************************************************/
+
+#ifndef PARTGUI_VIEWPROVIDERPREVIEWEXTENSION_H
+#define PARTGUI_VIEWPROVIDERPREVIEWEXTENSION_H
+
+#include "SoBrepEdgeSet.h"
+#include "SoBrepFaceSet.h"
+#include "SoBrepPointSet.h"
+
+#include <QtCore>
+
+#include <Inventor/nodes/SoSubNode.h>
+#include <Inventor/nodes/SoCoordinate3.h>
+#include <Inventor/nodes/SoNormal.h>
+#include <Inventor/nodes/SoSeparator.h>
+#include <Inventor/fields/SoSFColor.h>
+#include <Inventor/fields/SoSFFloat.h>
+
+#include <App/PropertyStandard.h>
+#include <Gui/ViewProvider.h>
+
+#include <Gui/ViewProviderExtension.h>
+#include <Gui/ViewProviderExtensionPython.h>
+#include <Mod/Part/App/TopoShape.h>
+
+namespace PartGui {
+
+class PartGuiExport SoPreviewShape : public SoSeparator {
+    using inherited = SoSeparator;
+    SO_NODE_HEADER(SoPreviewShape);
+
+public:
+    static constexpr float defaultTransparency = 0.8F;
+    static constexpr float defaultLineWidth = 2.0F;
+    static const SbColor defaultColor;
+
+    SoPreviewShape();
+
+    SoSFColor color;
+    SoSFFloat transparency;
+    SoSFFloat lineWidth;
+
+    SoCoordinate3* coords;
+    SoNormal* norm;
+
+    SoBrepFaceSet* faceset;
+    SoBrepEdgeSet* lineset;
+    SoBrepPointSet* nodeset;
+};
+
+class PartGuiExport ViewProviderPreviewExtension : public Gui::ViewProviderExtension {
+    Q_DECLARE_TR_FUNCTIONS(PartDesignGui::ViewProviderPreviewExtension)
+    EXTENSION_PROPERTY_HEADER_WITH_OVERRIDE(Gui::ViewProviderPreviewExtension);
+
+public:
+    App::PropertyColor PreviewColor;
+
+    ViewProviderPreviewExtension();
+
+    /// Returns shape that should be used as the preview
+    virtual Part::TopoShape getPreviewShape() const { return Part::TopoShape(); };
+
+    void extensionAttach(App::DocumentObject*) override;
+    void extensionBeforeDelete() override;
+
+    /// Returns whatever preview is enabled or not
+    bool isPreviewEnabled() const { return _isPreviewEnabled; }
+    /// Switches preview on or off
+    virtual void showPreview(bool enable);
+
+protected:
+    void extensionOnChanged(const App::Property* prop) override;
+
+    /// updates geometry of the preview shape
+    void updatePreviewShape();
+
+    Gui::CoinPtr<SoSeparator> pcPreviewRoot;
+    Gui::CoinPtr<SoPreviewShape> pcPreviewShape;
+
+private:
+    bool _isPreviewEnabled {false};
+};
+
+using ViewProviderPreviewExtensionPython = Gui::ViewProviderExtensionPythonT<ViewProviderPreviewExtension>;
+
+}
+
+
+#endif  // PARTGUI_VIEWPROVIDERPREVIEWEXTENSION_H

src/Mod/PartDesign/App/Feature.cpp

@@ -44,6 +44,8 @@
 #include "Body.h"
 #include "ShapeBinder.h"
 
+#include <BRep_Builder.hxx>
+
 FC_LOG_LEVEL_INIT("PartDesign", true, true)
 
 
@@ -70,6 +72,7 @@ Feature::Feature()
     BaseFeature.setStatus(App::Property::Hidden, true);
 
     App::SuppressibleExtension::initExtension(this);
+    Part::PreviewExtension::initExtension(this);
 }
 
 App::DocumentObjectExecReturn* Feature::recompute()
@@ -103,9 +106,17 @@ App::DocumentObjectExecReturn* Feature::recompute()
     if (!failed) {
         updateSuppressedShape();
     }
+
     return App::DocumentObject::StdReturn;
 }
 
+App::DocumentObjectExecReturn* Feature::recomputePreview()
+{
+    updatePreviewShape();
+
+    return StdReturn;
+}
+
 void Feature::setMaterialToBodyMaterial()
 {
     auto body = getFeatureBody();
@@ -172,7 +183,8 @@ void Feature::onChanged(const App::Property *prop)
 {
     if (!this->isRestoring()
         && this->getDocument()
-        && !this->getDocument()->isPerformingTransaction()) {
+        && !this->getDocument()->isPerformingTransaction()
+    ) {
         if (prop == &Visibility || prop == &BaseFeature) {
             auto body = Body::findBodyOf(this);
             if (body) {
@@ -343,6 +355,51 @@ Part::TopoShape Feature::getBaseTopoShape(bool silent) const
     return result;
 }
 
+void Feature::getGeneratedShapes(std::vector<int>& faces,
+                                 std::vector<int>& edges,
+                                 std::vector<int>& vertices) const
+{
+    static const auto addAllSubShapesToSet = [](
+        const Part::TopoShape& shape,
+        const Part::TopoShape& face,
+        TopAbs_ShapeEnum type,
+        std::set<int>& set
+    ) {
+        for (auto &subShape : face.getSubShapes(type)) {
+            if (int subShapeId = shape.findShape(subShape); subShapeId > 0) {
+                set.insert(subShapeId);
+            }
+        }
+    };
+
+    Part::TopoShape shape = Shape.getShape();
+
+    std::set<int> edgeSet;
+    std::set<int> vertexSet;
+
+    int count = shape.countSubShapes(TopAbs_FACE);
+
+    for (int faceId = 1; faceId <= count; ++faceId) {
+        if (Data::MappedName mapped = shape.getMappedName(Data::IndexedName::fromConst("Face", faceId));
+            shape.isElementGenerated(mapped)) {
+            faces.push_back(faceId);
+
+            Part::TopoShape face = shape.getSubTopoShape(TopAbs_FACE, faceId);
+
+            addAllSubShapesToSet(shape, face, TopAbs_EDGE, edgeSet);
+            addAllSubShapesToSet(shape, face, TopAbs_VERTEX, vertexSet);
+        }
+    }
+
+    std::ranges::copy(edgeSet, std::back_inserter(edges));
+    std::ranges::copy(vertexSet, std::back_inserter(vertices));
+}
+
+void Feature::updatePreviewShape()
+{
+    // no-op
+}
+
 PyObject* Feature::getPyObject()
 {
     if (PythonObject.is(Py::_None())){

src/Mod/PartDesign/App/Feature.h

@@ -27,6 +27,7 @@
 #include <App/PropertyStandard.h>
 #include <App/SuppressibleExtension.h>
 #include <Mod/Part/App/PartFeature.h>
+#include <Mod/Part/App/PreviewExtension.h>
 #include <Mod/PartDesign/PartDesignGlobal.h>
 
 class gp_Pnt;
@@ -45,7 +46,7 @@ class Body;
  *   Base class of all PartDesign features.
  *   This kind of features only produce solids or fail.
  */
-class PartDesignExport Feature : public Part::Feature, public App::SuppressibleExtension
+class PartDesignExport Feature : public Part::Feature, public App::SuppressibleExtension, public Part::PreviewExtension
 {
     PROPERTY_HEADER_WITH_OVERRIDE(PartDesign::Feature);
 
@@ -62,7 +63,9 @@ public:
     Part::PropertyPartShape SuppressedShape;
     /// Keep a copy of the placement before suppression to restore it back when unsuppressed, fix #20205
     Base::Placement SuppressedPlacement;
+
     App::DocumentObjectExecReturn* recompute() override;
+    App::DocumentObjectExecReturn* recomputePreview() override;
 
     short mustExecute() const override;
 
@@ -84,6 +87,13 @@ public:
     /// Returns the BaseFeature property's TopoShape (if any)
     Part::TopoShape getBaseTopoShape(bool silent=false) const;
 
+    // Fills up information about which sub-shapes were generated by the feature
+    virtual void getGeneratedShapes(std::vector<int>& faces,
+                            std::vector<int>& edges,
+                            std::vector<int>& vertices) const;
+
+    virtual void updatePreviewShape();
+
     PyObject* getPyObject() override;
 
     const char* getViewProviderName() const override {

src/Mod/PartDesign/App/FeatureAddSub.cpp

@@ -28,10 +28,13 @@
 
 #include <App/FeaturePythonPyImp.h>
 #include <Mod/Part/App/modelRefine.h>
+#include <Mod/Part/App/TopoShapeOpCode.h>
 
 #include "FeatureAddSub.h"
 #include "FeaturePy.h"
 
+#include <Mod/Part/App/Tools.h>
+
 
 using namespace PartDesign;
 
@@ -43,7 +46,12 @@ PROPERTY_SOURCE(PartDesign::FeatureAddSub, PartDesign::FeatureRefine)
 
 FeatureAddSub::FeatureAddSub()
 {
-    ADD_PROPERTY(AddSubShape,(TopoDS_Shape()));
+    ADD_PROPERTY(AddSubShape, (TopoDS_Shape()));
+}
+
+void FeatureAddSub::onChanged(const App::Property* property)
+{
+    Feature::onChanged(property);
 }
 
 FeatureAddSub::Type FeatureAddSub::getAddSubType()
@@ -58,16 +66,53 @@ short FeatureAddSub::mustExecute() const
     return PartDesign::Feature::mustExecute();
 }
 
-void FeatureAddSub::getAddSubShape(Part::TopoShape &addShape, Part::TopoShape &subShape)
+void FeatureAddSub::getAddSubShape(Part::TopoShape& addShape, Part::TopoShape& subShape)
 {
-    if (addSubType == Additive)
+    if (addSubType == Additive) {
         addShape = AddSubShape.getShape();
-    else if (addSubType == Subtractive)
+    }
+    else if (addSubType == Subtractive) {
         subShape = AddSubShape.getShape();
+    }
 }
 
+void FeatureAddSub::updatePreviewShape()
+{
+    const auto notifyWarning = [](const QString& message) {
+        Base::Console().translatedUserWarning(
+            "Preview",
+            tr("Failure while computing removed volume preview: %1")
+                .arg(message)
+                .toUtf8());
+    };
+
+    // for subtractive shapes we want to also showcase removed volume, not only the tool
+    if (addSubType == Subtractive) {
+        TopoShape base = getBaseTopoShape(true).moved(getLocation().Inverted());
+
+        if (const TopoShape& addSubShape = AddSubShape.getShape(); !addSubShape.isEmpty()) {
+            try {
+                base.makeElementBoolean(Part::OpCodes::Common, { base, addSubShape });
+            } catch (Standard_Failure& e) {
+                notifyWarning(QString::fromUtf8(e.GetMessageString()));
+            } catch (Base::Exception& e) {
+                notifyWarning(QString::fromStdString(e.getMessage()));
+            }
+
+            if (base.isEmpty()) {
+                notifyWarning(tr("Resulting shape is empty. That may indicate that no material will be removed or a problem with the model."));
+            }
+
+            PreviewShape.setValue(base);
+            return;
+        }
+    }
+
+    PreviewShape.setValue(AddSubShape.getShape());
 }
 
+}  // namespace PartDesign
+
 namespace App {
 /// @cond DOXERR
 PROPERTY_SOURCE_TEMPLATE(PartDesign::FeatureAddSubPython, PartDesign::FeatureAddSub)

src/Mod/PartDesign/App/FeatureAddSub.h

@@ -26,12 +26,15 @@
 
 #include "FeatureRefine.h"
 
+#include <QtCore>
+
 /// Base class of all additive features in PartDesign
 namespace PartDesign
 {
 
 class PartDesignExport FeatureAddSub : public PartDesign::FeatureRefine
 {
+    Q_DECLARE_TR_FUNCTIONS(PartDesign::FeatureAddSub)
     PROPERTY_HEADER_WITH_OVERRIDE(PartDesign::FeatureAddSub);
 
 public:
@@ -42,12 +45,15 @@ public:
 
     FeatureAddSub();
 
+    void onChanged(const App::Property *) override;
     Type getAddSubType();
 
     short mustExecute() const override;
 
     virtual void getAddSubShape(Part::TopoShape &addShape, Part::TopoShape &subShape);
 
+    void updatePreviewShape() override;
+
     Part::PropertyPartShape   AddSubShape;
 
 

src/Mod/PartDesign/App/FeatureDressUp.cpp

@@ -293,53 +293,62 @@ void DressUp::onChanged(const App::Property* prop)
     Feature::onChanged(prop);
 }
 
-void DressUp::getAddSubShape(Part::TopoShape &addShape, Part::TopoShape &subShape)
+void DressUp::getAddSubShape(Part::TopoShape& addShape, Part::TopoShape& subShape)
 {
     Part::TopoShape res = AddSubShape.getShape();
 
-    if(res.isNull()) {
+    if (res.isNull()) {
         try {
             std::vector<Part::TopoShape> shapes;
             Part::TopoShape shape = Shape.getShape();
             shape.setPlacement(Base::Placement());
 
-            FeatureAddSub *base = nullptr;
-            if(SupportTransform.getValue()) {
+            FeatureAddSub* base = nullptr;
+            if (SupportTransform.getValue()) {
                 // SupportTransform means transform the support together with
                 // the dressing. So we need to find the previous support
                 // feature (which must be of type FeatureAddSub), and skipping
                 // any consecutive DressUp in-between.
-                for(Feature *current=this; ;current=static_cast<DressUp*>(base)) {
+                for (Feature* current = this;; current = static_cast<DressUp*>(base)) {
                     base = freecad_cast<FeatureAddSub*>(current->getBaseObject(true));
-                    if(!base)
+                    if (!base) {
                         FC_THROWM(Base::CADKernelError,
-                                "Cannot find additive or subtractive support for " << getFullName());
-                    if(!base->isDerivedFrom<DressUp>())
+                                  "Cannot find additive or subtractive support for "
+                                      << getFullName());
+                    }
+                    if (!base->isDerivedFrom<DressUp>()) {
                         break;
+                    }
                 }
             }
 
             Part::TopoShape baseShape;
-            if(base) {
+            if (base) {
                 baseShape = base->getBaseTopoShape(true);
                 baseShape.move(base->getLocation().Inverted());
                 if (base->getAddSubType() == Additive) {
-                    if(!baseShape.isNull() && baseShape.hasSubShape(TopAbs_SOLID))
+                    if (!baseShape.isNull() && baseShape.hasSubShape(TopAbs_SOLID)) {
                         shapes.emplace_back(shape.makeElementCut(baseShape.getShape()));
-                    else
+                    }
+                    else {
                         shapes.push_back(shape);
-                } else {
+                    }
+                }
+                else {
                     BRep_Builder builder;
                     TopoDS_Compound comp;
                     builder.MakeCompound(comp);
                     // push an empty compound to indicate null additive shape
                     shapes.emplace_back(comp);
-                    if(!baseShape.isNull() && baseShape.hasSubShape(TopAbs_SOLID))
+                    if (!baseShape.isNull() && baseShape.hasSubShape(TopAbs_SOLID)) {
                         shapes.emplace_back(baseShape.makeElementCut(shape.getShape()));
-                    else
+                    }
+                    else {
                         shapes.push_back(shape);
+                    }
                 }
-            } else {
+            }
+            else {
                 baseShape = getBaseTopoShape();
                 baseShape.move(getLocation().Inverted());
                 shapes.emplace_back(shape.makeElementCut(baseShape.getShape()));
@@ -350,34 +359,73 @@ void DressUp::getAddSubShape(Part::TopoShape &addShape, Part::TopoShape &subShap
             // bceause a dressing (e.g. a fillet) can either be additive or
             // subtractive. And the dressup feature can contain mixture of both.
             AddSubShape.setValue(Part::TopoShape().makeElementCompound(shapes));
-
-        } catch (Standard_Failure &e) {
-            FC_THROWM(Base::CADKernelError, "Failed to calculate AddSub shape: "
-                    << e.GetMessageString());
+        }
+        catch (Standard_Failure& e) {
+            FC_THROWM(Base::CADKernelError,
+                      "Failed to calculate AddSub shape: " << e.GetMessageString());
         }
         res = AddSubShape.getShape();
     }
 
-    if(res.isNull())
+    if (res.isNull()) {
         throw Part::NullShapeException("Null AddSub shape");
+    }
 
-    if(res.getShape().ShapeType() != TopAbs_COMPOUND) {
+    if (res.getShape().ShapeType() != TopAbs_COMPOUND) {
         addShape = res;
-    } else {
+    }
+    else {
         int count = res.countSubShapes(TopAbs_SHAPE);
-        if(!count)
+        if (!count) {
             throw Part::NullShapeException("Null AddSub shape");
-        if(count) {
-            Part::TopoShape s = res.getSubTopoShape(TopAbs_SHAPE, 1);
-            if(!s.isNull() && s.hasSubShape(TopAbs_SOLID))
-                addShape = s;
         }
-        if(count > 1) {
+        if (count) {
+            Part::TopoShape s = res.getSubTopoShape(TopAbs_SHAPE, 1);
+            if (!s.isNull() && s.hasSubShape(TopAbs_SOLID)) {
+                addShape = s;
+            }
+        }
+        if (count > 1) {
             Part::TopoShape s = res.getSubTopoShape(TopAbs_SHAPE, 2);
-            if(!s.isNull() && s.hasSubShape(TopAbs_SOLID))
+            if (!s.isNull() && s.hasSubShape(TopAbs_SOLID)) {
                 subShape = s;
+            }
         }
     }
 }
 
+void DressUp::updatePreviewShape()
+{
+    auto shape = Shape.getShape();
+    auto baseFeature = freecad_cast<Feature*>(BaseFeature.getValue());
+
+    if (!baseFeature || baseFeature->Shape.getShape().isNull()) {
+        PreviewShape.setValue(Shape.getShape());
+        return;
+    }
+
+    std::vector<int> faces, edges, vertices;
+    getGeneratedShapes(faces, edges, vertices);
+
+    if (faces.empty()) {
+        PreviewShape.setValue(TopoDS_Shape());
+        return;
+    }
+
+    shape.setPlacement(Base::Placement());
+
+    BRep_Builder builder;
+    TopoDS_Compound comp;
+    builder.MakeCompound(comp);
+
+    for (int faceId : faces) {
+        builder.Add(comp, shape.getSubShape(TopAbs_FACE, faceId));
+    }
+
+    Part::TopoShape preview(comp);
+    preview.mapSubElement(shape);
+
+    PreviewShape.setValue(preview);
 }
+
+}  // namespace PartDesign

src/Mod/PartDesign/App/FeatureDressUp.h

@@ -65,6 +65,7 @@ public:
 
     std::vector<TopoShape> getFaces(const TopoShape &shape);
     void getAddSubShape(Part::TopoShape &addShape, Part::TopoShape &subShape) override;
+    void updatePreviewShape() override;
 
 protected:
     void onChanged(const App::Property* prop) override;

src/Mod/PartDesign/App/FeaturePrimitive.cpp

@@ -150,10 +150,11 @@ App::DocumentObjectExecReturn* FeaturePrimitive::execute(const TopoDS_Shape& pri
 
 void FeaturePrimitive::onChanged(const App::Property* prop)
 {
-    if (prop == &AttachmentOffset){
-        this->touch();
+    if (prop == &AttachmentOffset) {
+        this->recompute();
         return;
     }
+
     FeatureAddSub::onChanged(prop);
 }
 

src/Mod/PartDesign/Gui/AppPartDesignGui.cpp

@@ -155,7 +155,6 @@ PyMOD_INIT_FUNC(PartDesignGui)
     PartDesignGui::ViewProviderSubShapeBinder::init();
     PartDesignGui::ViewProviderSubShapeBinderPython::init();
     PartDesignGui::ViewProviderBoolean       ::init();
-    PartDesignGui::ViewProviderAddSub        ::init();
     PartDesignGui::ViewProviderPrimitive     ::init();
     PartDesignGui::ViewProviderPipe          ::init();
     PartDesignGui::ViewProviderLoft          ::init();

src/Mod/PartDesign/Gui/CMakeLists.txt

@@ -109,8 +109,6 @@ SET(PartDesignGuiViewProvider_SRCS
     ViewProviderShapeBinder.cpp
     ViewProviderBoolean.cpp
     ViewProviderBoolean.h
-    ViewProviderAddSub.cpp
-    ViewProviderAddSub.h
     ViewProviderPrimitive.h
     ViewProviderPrimitive.cpp
     ViewProviderPipe.h

src/Mod/PartDesign/Gui/TaskChamferParameters.cpp

@@ -182,7 +182,7 @@ void TaskChamferParameters::onCheckBoxUseAllEdgesToggled(bool checked)
 void TaskChamferParameters::setButtons(const selectionModes mode)
 {
     ui->buttonRefSel->setChecked(mode == refSel);
-    ui->buttonRefSel->setText(mode == refSel ? btnPreviewStr() : btnSelectStr());
+    ui->buttonRefSel->setText(mode == refSel ? stopSelectionLabel() : startSelectionLabel());
 }
 
 void TaskChamferParameters::onRefDeleted()
@@ -349,7 +349,7 @@ bool TaskDlgChamferParameters::accept()
 {
     auto obj = getObject();
     if (!obj->isError()) {
-        parameter->showObject();
+        getViewObject()->showPreviousFeature(false);
     }
 
     parameter->apply();

src/Mod/PartDesign/Gui/TaskDraftParameters.cpp

@@ -170,7 +170,7 @@ void TaskDraftParameters::onSelectionChanged(const Gui::SelectionChanges& msg)
 
 void TaskDraftParameters::setButtons(const selectionModes mode)
 {
-    ui->buttonRefSel->setText(mode == refSel ? btnPreviewStr() : btnSelectStr());
+    ui->buttonRefSel->setText(mode == refSel ? stopSelectionLabel() : startSelectionLabel());
     ui->buttonRefSel->setChecked(mode == refSel);
     ui->buttonLine->setChecked(mode == line);
     ui->buttonPlane->setChecked(mode == plane);
@@ -180,7 +180,7 @@ void TaskDraftParameters::onButtonPlane(bool checked)
 {
     if (checked) {
         setButtons(plane);
-        hideObject();
+        getViewObject()->showPreviousFeature(true);
         selectionMode = plane;
         Gui::Selection().clearSelection();
         Gui::Selection().addSelectionGate(new ReferenceSelection(
@@ -193,7 +193,7 @@ void TaskDraftParameters::onButtonLine(bool checked)
 {
     if (checked) {
         setButtons(line);
-        hideObject();
+        getViewObject()->showPreviousFeature(true);
         selectionMode = line;
         Gui::Selection().clearSelection();
         Gui::Selection().addSelectionGate(
@@ -311,7 +311,7 @@ bool TaskDlgDraftParameters::accept()
 {
     auto tobj = getObject();
     if (!tobj->isError()) {
-        parameter->showObject();
+        getViewObject()->showPreviousFeature(false);
     }
 
     parameter->apply();

src/Mod/PartDesign/Gui/TaskDressUpParameters.cpp

@@ -55,10 +55,7 @@ using namespace Gui;
 /* TRANSLATOR PartDesignGui::TaskDressUpParameters */
 
 TaskDressUpParameters::TaskDressUpParameters(ViewProviderDressUp *DressUpView, bool selectEdges, bool selectFaces, QWidget *parent)
-    : TaskBox(Gui::BitmapFactory().pixmap(DressUpView->featureIcon().c_str()),
-              DressUpView->menuName,
-              true,
-              parent)
+    : TaskFeatureParameters(DressUpView, parent, DressUpView->featureIcon(), DressUpView->menuName)
     , proxy(nullptr)
     , deleteAction(nullptr)
     , addAllEdgesAction(nullptr)
@@ -70,7 +67,6 @@ TaskDressUpParameters::TaskDressUpParameters(ViewProviderDressUp *DressUpView, b
     App::GetApplication().getActiveTransaction(&transactionID);
 
     selectionMode = none;
-    showObject();
 }
 
 TaskDressUpParameters::~TaskDressUpParameters()
@@ -282,6 +278,16 @@ void TaskDressUpParameters::tryAddSelection(const std::string& doc,
     }
 }
 
+QString TaskDressUpParameters::startSelectionLabel()
+{
+    return tr("Select");
+}
+
+QString TaskDressUpParameters::stopSelectionLabel()
+{
+    return tr("Confirm Selection");
+}
+
 void TaskDressUpParameters::itemClickedTimeout() {
     // executed after double-click time passed
     wasDoubleClicked = false;
@@ -368,34 +374,7 @@ void TaskDressUpParameters::removeItemFromListWidget(QListWidget* widget, const
 void TaskDressUpParameters::hideOnError()
 {
     App::DocumentObject* dressup = DressUpView->getObject();
-    if (dressup->isError())
-        hideObject();
-    else
-        showObject();
-}
-
-void TaskDressUpParameters::setDressUpVisibility(bool visible)
-{
-    App::DocumentObject* base = getBase();
-    if (base) {
-        App::DocumentObject* duv = DressUpView->getObject();
-        if (duv->Visibility.getValue() != visible) {
-            duv->Visibility.setValue(visible);
-        }
-        if (base->Visibility.getValue() == visible) {
-            base->Visibility.setValue(!visible);
-        }
-    }
-}
-
-void TaskDressUpParameters::hideObject()
-{
-    setDressUpVisibility(false);
-}
-
-void TaskDressUpParameters::showObject()
-{
-    setDressUpVisibility(true);
+    DressUpView->setErrorState(dressup->isError());
 }
 
 ViewProviderDressUp* TaskDressUpParameters::getDressUpView() const
@@ -427,16 +406,12 @@ void TaskDressUpParameters::setSelectionMode(selectionModes mode)
     setButtons(mode);
 
     if (mode == none) {
-        showObject();
-
         Gui::Selection().rmvSelectionGate();
 
         // remove any highlights and selections
         DressUpView->highlightReferences(false);
     }
     else {
-        hideObject();
-
         AllowSelectionFlags allow;
         allow.setFlag(AllowSelection::EDGE, allowEdges);
         allow.setFlag(AllowSelection::FACE, allowFaces);

src/Mod/PartDesign/Gui/TaskDressUpParameters.h

@@ -42,7 +42,7 @@ namespace Part {
 
 namespace PartDesignGui {
 
-class TaskDressUpParameters : public Gui::TaskView::TaskBox, public Gui::SelectionObserver
+class TaskDressUpParameters : public TaskFeatureParameters, public Gui::SelectionObserver
 {
     Q_OBJECT
 
@@ -53,13 +53,8 @@ public:
     const std::vector<std::string> getReferences() const;
     Part::Feature *getBase() const;
 
-    void hideObject();
-    void showObject();
     void setupTransaction();
 
-    /// Apply the changes made to the object to it
-    virtual void apply() {}
-
     int getTransactionID() const {
         return transactionID;
     }
@@ -92,17 +87,6 @@ protected:
 
     ViewProviderDressUp* getDressUpView() const;
 
-    template<typename T = App::DocumentObject> T* getObject() const
-    {
-        static_assert(std::is_base_of<App::DocumentObject, T>::value, "Wrong template argument");
-
-        if (!DressUpView.expired()) {
-            return DressUpView->getObject<T>();
-        }
-
-        return nullptr;
-    }
-
 private:
     void tryAddSelection(const std::string& doc, const std::string& obj, const std::string& sub);
     void setDressUpVisibility(bool visible);
@@ -116,8 +100,8 @@ protected:
     selectionModes selectionMode;
     int transactionID;
 
-    static const QString btnPreviewStr();
-    static const QString btnSelectStr();
+    static QString stopSelectionLabel();
+    static QString startSelectionLabel();
 
 private:
     Gui::WeakPtrT<ViewProviderDressUp> DressUpView;

src/Mod/PartDesign/Gui/TaskExtrudeParameters.cpp

@@ -32,7 +32,6 @@
 #include <Gui/Command.h>
 #include <Gui/Tools.h>
 #include <Mod/PartDesign/App/FeatureExtrude.h>
-#include <Mod/Part/Gui/ReferenceHighlighter.h>
 
 #include "ui_TaskPadPocketParameters.h"
 #include "TaskExtrudeParameters.h"

src/Mod/PartDesign/Gui/TaskFeatureParameters.cpp

@@ -52,6 +52,9 @@ TaskFeatureParameters::TaskFeatureParameters(PartDesignGui::ViewProvider *vp, QW
 {
     Gui::Document* doc = vp->getDocument();
     this->attachDocument(doc);
+
+    vp->showPreviousFeature(true);
+    vp->showPreview(true);
 }
 
 void TaskFeatureParameters::slotDeletedObject(const Gui::ViewProviderDocumentObject& Obj)

src/Mod/PartDesign/Gui/TaskFilletParameters.cpp

@@ -134,7 +134,7 @@ void TaskFilletParameters::onCheckBoxUseAllEdgesToggled(bool checked)
 void TaskFilletParameters::setButtons(const selectionModes mode)
 {
     ui->buttonRefSel->setChecked(mode == refSel);
-    ui->buttonRefSel->setText(mode == refSel ? btnPreviewStr() : btnSelectStr());
+    ui->buttonRefSel->setText(mode == refSel ? stopSelectionLabel() : startSelectionLabel());
 }
 
 void TaskFilletParameters::onRefDeleted()
@@ -216,7 +216,7 @@ bool TaskDlgFilletParameters::accept()
 {
     auto obj = getObject();
     if (!obj->isError()) {
-        parameter->showObject();
+        getViewObject()->showPreviousFeature(false);
     }
 
     parameter->apply();

src/Mod/PartDesign/Gui/TaskHelixParameters.ui

@@ -286,7 +286,7 @@
    <item>
     <widget class="QCheckBox" name="checkBoxUpdateView">
      <property name="text">
-      <string>Update view</string>
+      <string>Recompute on change</string>
      </property>
      <property name="checked">
       <bool>true</bool>

src/Mod/PartDesign/Gui/TaskHoleParameters.cpp

@@ -241,8 +241,6 @@ TaskHoleParameters::TaskHoleParameters(ViewProviderHole* HoleView, QWidget* pare
             this, &TaskHoleParameters::baseProfileTypeChanged);
     // clang-format on
 
-    getViewObject()->show();
-
     ui->Diameter->bind(pcHole->Diameter);
     ui->HoleCutDiameter->bind(pcHole->HoleCutDiameter);
     ui->HoleCutDepth->bind(pcHole->HoleCutDepth);

src/Mod/PartDesign/Gui/TaskLoftParameters.ui

@@ -117,7 +117,7 @@
    <item>
     <widget class="QCheckBox" name="checkBoxUpdateView">
      <property name="text">
-      <string>Update view</string>
+      <string>Recompute on change</string>
      </property>
      <property name="checked">
       <bool>true</bool>

src/Mod/PartDesign/Gui/TaskPadPocketParameters.ui

@@ -468,7 +468,7 @@ measured along the specified direction</string>
    <item>
     <widget class="QCheckBox" name="checkBoxUpdateView">
      <property name="text">
-      <string>Update view</string>
+      <string>Recompute on change</string>
      </property>
      <property name="checked">
       <bool>true</bool>

src/Mod/PartDesign/Gui/TaskPrimitiveParameters.cpp

@@ -52,6 +52,9 @@ TaskBoxPrimitives::TaskBoxPrimitives(ViewProviderPrimitive* vp, QWidget* parent)
   , ui(new Ui_DlgPrimitives)
   , vp(vp)
 {
+    vp->showPreview(true);
+    vp->showPreviousFeature(true);
+
     proxy = new QWidget(this);
     ui->setupUi(proxy);
 
@@ -972,8 +975,9 @@ bool TaskBoxPrimitives::setPrimitive(App::DocumentObject* obj)
     return true;
 }
 
-TaskPrimitiveParameters::TaskPrimitiveParameters(ViewProviderPrimitive* PrimitiveView)
-    : vp_prm(PrimitiveView)
+TaskDlgPrimitiveParameters::TaskDlgPrimitiveParameters(ViewProviderPrimitive* PrimitiveView)
+    : TaskDlgFeatureParameters(PrimitiveView)
+    , vp_prm(PrimitiveView)
 {
     assert(PrimitiveView);
 
@@ -983,9 +987,9 @@ TaskPrimitiveParameters::TaskPrimitiveParameters(ViewProviderPrimitive* Primitiv
     Content.push_back(parameter);
 }
 
-TaskPrimitiveParameters::~TaskPrimitiveParameters() = default;
+TaskDlgPrimitiveParameters::~TaskDlgPrimitiveParameters() = default;
 
-bool TaskPrimitiveParameters::accept()
+bool TaskDlgPrimitiveParameters::accept()
 {
     bool primitiveOK = primitive->setPrimitive(vp_prm->getObject());
     if (!primitiveOK) {
@@ -997,7 +1001,7 @@ bool TaskPrimitiveParameters::accept()
     return true;
 }
 
-bool TaskPrimitiveParameters::reject()
+bool TaskDlgPrimitiveParameters::reject()
 {
     // roll back the done things
     Gui::Command::abortCommand();
@@ -1006,7 +1010,7 @@ bool TaskPrimitiveParameters::reject()
     return true;
 }
 
-QDialogButtonBox::StandardButtons TaskPrimitiveParameters::getStandardButtons() const
+QDialogButtonBox::StandardButtons TaskDlgPrimitiveParameters::getStandardButtons() const
 {
     return Gui::TaskView::TaskDialog::getStandardButtons();
 }

src/Mod/PartDesign/Gui/TaskPrimitiveParameters.h

@@ -31,6 +31,7 @@
 
 #include "ViewProviderPrimitive.h"
 #include "TaskDatumParameters.h"
+#include "TaskFeatureParameters.h"
 
 namespace App {
 class Property;
@@ -117,13 +118,13 @@ private:
     ViewProviderPrimitive* vp;
 };
 
-class TaskPrimitiveParameters : public Gui::TaskView::TaskDialog
+class TaskDlgPrimitiveParameters : public TaskDlgFeatureParameters
 {
     Q_OBJECT
 
 public:
-    explicit TaskPrimitiveParameters(ViewProviderPrimitive *PrimitiveView);
-    ~TaskPrimitiveParameters() override;
+    explicit TaskDlgPrimitiveParameters(ViewProviderPrimitive *PrimitiveView);
+    ~TaskDlgPrimitiveParameters() override;
 
 protected:
     QDialogButtonBox::StandardButtons getStandardButtons() const override;

src/Mod/PartDesign/Gui/TaskRevolutionParameters.ui

@@ -189,7 +189,7 @@
    <item>
     <widget class="QCheckBox" name="checkBoxUpdateView">
      <property name="text">
-      <string>Update view</string>
+      <string>Recompute on change</string>
      </property>
      <property name="checked">
       <bool>true</bool>

src/Mod/PartDesign/Gui/TaskSketchBasedParameters.cpp

@@ -90,22 +90,37 @@ const QString TaskSketchBasedParameters::onAddSelection(const Gui::SelectionChan
 void TaskSketchBasedParameters::startReferenceSelection(App::DocumentObject* profile,
                                                         App::DocumentObject* base)
 {
-    if (Gui::Document* doc = getGuiDocument()) {
-        doc->setHide(profile->getNameInDocument());
-        if (base) {
-            doc->setShow(base->getNameInDocument());
+    const auto* bodyViewProvider = getViewObject<ViewProvider>()->getBodyViewProvider();
+
+    previouslyVisibleViewProvider = bodyViewProvider->getShownViewProvider();
+
+    if (!base) {
+        return;
+    }
+
+    if (Document* doc = getGuiDocument()) {
+        if (previouslyVisibleViewProvider) {
+            previouslyVisibleViewProvider->hide();
         }
+
+        doc->setShow(base->getNameInDocument());
     }
 }
 
 void TaskSketchBasedParameters::finishReferenceSelection(App::DocumentObject* profile,
                                                          App::DocumentObject* base)
 {
-    if (Gui::Document* doc = getGuiDocument()) {
-        doc->setShow(profile->getNameInDocument());
+    if (!previouslyVisibleViewProvider) {
+        return;
+    }
+
+    if (Document* doc = getGuiDocument()) {
         if (base) {
             doc->setHide(base->getNameInDocument());
         }
+
+        previouslyVisibleViewProvider->show();
+        previouslyVisibleViewProvider = nullptr;
     }
 }
 

src/Mod/PartDesign/Gui/TaskSketchBasedParameters.h

@@ -72,6 +72,9 @@ protected:
     /// or the subelement's name if the object is a solid.
     QString make2DLabel(const App::DocumentObject* section,
                         const std::vector<std::string>& subValues);
+
+private:
+    Gui::ViewProvider* previouslyVisibleViewProvider {nullptr};
 };
 
 class TaskDlgSketchBasedParameters : public PartDesignGui::TaskDlgFeatureParameters

src/Mod/PartDesign/Gui/TaskThicknessParameters.cpp

@@ -144,7 +144,7 @@ void TaskThicknessParameters::onSelectionChanged(const Gui::SelectionChanges& ms
 void TaskThicknessParameters::setButtons(const selectionModes mode)
 {
     ui->buttonRefSel->setChecked(mode == refSel);
-    ui->buttonRefSel->setText(mode == refSel ? btnPreviewStr() : btnSelectStr());
+    ui->buttonRefSel->setText(mode == refSel ? stopSelectionLabel() : startSelectionLabel());
 }
 
 void TaskThicknessParameters::onRefDeleted()
@@ -280,7 +280,7 @@ bool TaskDlgThicknessParameters::accept()
 {
     auto obj = getObject();
     if (!obj->isError()) {
-        parameter->showObject();
+        getViewObject()->showPreviousFeature(false);
     }
 
     parameter->apply();

src/Mod/PartDesign/Gui/TaskTransformedParameters.ui

@@ -119,7 +119,7 @@
    <item>
     <widget class="QCheckBox" name="checkBoxUpdateView">
      <property name="text">
-      <string>Update view</string>
+      <string>Recompute on change</string>
      </property>
      <property name="checked">
       <bool>true</bool>

src/Mod/PartDesign/Gui/ViewProvider.cpp

@@ -26,8 +26,10 @@
 #ifndef _PreComp_
 # include <QMessageBox>
 # include <QAction>
-# include <QApplication>
 # include <QMenu>
+# include <Inventor/nodes/SoSeparator.h>
+# include <Inventor/nodes/SoPickStyle.h>
+# include <BRep_Builder.hxx>
 #endif
 
 #include <Base/Exception.h>
@@ -37,15 +39,23 @@
 #include <Gui/CommandT.h>
 #include <Gui/Control.h>
 #include <Gui/Document.h>
+#include <Gui/Selection/SoFCUnifiedSelection.h>
+#include <Gui/Inventor/So3DAnnotation.h>
 #include <Gui/MainWindow.h>
+#include <Gui/Utilities.h>
 #include <Mod/PartDesign/App/Body.h>
-#include <Mod/PartDesign/App/Feature.h>
+#include <Mod/PartDesign/App/FeatureAddSub.h>
+#include <Mod/Part/Gui/ViewProvider.h>
+#include <Mod/Part/Gui/ViewProviderExt.h>
+#include <Mod/Part/Gui/SoBrepEdgeSet.h>
+#include <Mod/Part/Gui/ViewProviderPreviewExtension.h>
 
 #include "TaskFeatureParameters.h"
 
 #include "ViewProvider.h"
 #include "ViewProviderPy.h"
 
+
 using namespace PartDesignGui;
 
 PROPERTY_SOURCE_WITH_EXTENSIONS(PartDesignGui::ViewProvider, PartGui::ViewProviderPart)
@@ -53,11 +63,31 @@ PROPERTY_SOURCE_WITH_EXTENSIONS(PartDesignGui::ViewProvider, PartGui::ViewProvid
 ViewProvider::ViewProvider()
 {
     ViewProviderSuppressibleExtension::initExtension(this);
-    PartGui::ViewProviderAttachExtension::initExtension(this);
+    ViewProviderAttachExtension::initExtension(this);
+    ViewProviderPreviewExtension::initExtension(this);
 }
 
 ViewProvider::~ViewProvider() = default;
 
+void ViewProvider::beforeDelete()
+{
+    ViewProviderPart::beforeDelete();
+}
+
+void ViewProvider::attach(App::DocumentObject* pcObject)
+{
+    ViewProviderPart::attach(pcObject);
+
+    if (auto addSubFeature = getObject<PartDesign::FeatureAddSub>()) {
+        const Base::Color green(0.0F, 1.0F, 0.6F);
+        const Base::Color red(1.0F, 0.0F, 0.0F);
+
+        bool isAdditive = addSubFeature->getAddSubType() == PartDesign::FeatureAddSub::Additive;
+
+        PreviewColor.setValue(isAdditive ? green : red);
+    }
+}
+
 bool ViewProvider::doubleClicked()
 {
     try {
@@ -149,6 +179,8 @@ TaskDlgFeatureParameters *ViewProvider::getEditDialog() {
 
 void ViewProvider::unsetEdit(int ModNum)
 {
+    showPreview(false);
+
     // return to the WB we were in before editing the PartDesign feature
     if (!oldWb.empty()) {
         Gui::Command::assureWorkbench(oldWb.c_str());
@@ -170,15 +202,42 @@ void ViewProvider::unsetEdit(int ModNum)
 
 void ViewProvider::updateData(const App::Property* prop)
 {
-    // TODO What's that? (2015-07-24, Fat-Zer)
-    if (prop->is<Part::PropertyPartShape>() &&
-        strcmp(prop->getName(),"AddSubShape") == 0) {
-        return;
+    if (strcmp(prop->getName(), "PreviewShape") == 0) {
+        updatePreviewShape();
     }
 
     inherited::updateData(prop);
 }
 
+void ViewProvider::attachPreview()
+{
+    ViewProviderPreviewExtension::attachPreview();
+
+    pcToolPreview = new PartGui::SoPreviewShape;
+    pcToolPreview->transparency = 0.95F;
+    pcToolPreview->color.connectFrom(&pcPreviewShape->color);
+
+    pcPreviewRoot->addChild(pcToolPreview);
+}
+
+void ViewProvider::updatePreview()
+{
+    ViewProviderPreviewExtension::updatePreview();
+
+    if (auto* addSubFeature = getObject<PartDesign::FeatureAddSub>()) {
+        // we only want to show the additional tool preview for subtractive features
+        if (addSubFeature->getAddSubType() != PartDesign::FeatureAddSub::Subtractive) {
+            return;
+        }
+
+        Part::TopoShape toolShape = addSubFeature->AddSubShape.getShape();
+
+        updatePreviewShape(toolShape, pcToolPreview);
+    } else {
+        updatePreviewShape({}, pcToolPreview);
+    }
+}
+
 void ViewProvider::onChanged(const App::Property* prop) {
 
     //if the object is inside of a body we make sure it is the only visible one on activation
@@ -267,12 +326,52 @@ bool ViewProvider::onDelete(const std::vector<std::string>&)
         //
         // fixes (#3084)
 
-        FCMD_OBJ_CMD(body,"removeObject(" << Gui::Command::getObjectCmd(feature) << ')');
+        FCMD_OBJ_CMD(body, "removeObject(" << Gui::Command::getObjectCmd(feature) << ')');
     }
 
     return true;
 }
 
+Part::TopoShape ViewProvider::getPreviewShape() const
+{
+    if (auto feature = getObject()->getExtensionByType<Part::PreviewExtension>(true)) {
+        // Feature is responsible for generating proper shape and this ViewProvider
+        // is using it instead of more normal `Shape` property.
+        return feature->PreviewShape.getShape();
+    }
+
+    return {};
+}
+
+void ViewProvider::showPreviousFeature(bool enable)
+{
+    PartDesign::Feature* feature {getObject<PartDesign::Feature>()};
+    PartDesign::Feature* baseFeature { nullptr };
+
+    ViewProvider* baseFeatureViewProvider { nullptr };
+
+    if (!feature) {
+        return;
+    }
+
+    baseFeature = dynamic_cast<PartDesign::Feature*>(feature->BaseFeature.getValue());
+    if (baseFeature) {
+        baseFeatureViewProvider = freecad_cast<ViewProvider*>(Gui::Application::Instance->getViewProvider(baseFeature));
+    }
+
+    if (!baseFeatureViewProvider) {
+        baseFeatureViewProvider = this;
+    }
+
+    if (enable) {
+        baseFeatureViewProvider->show();
+        hide();
+    } else {
+        baseFeatureViewProvider->hide();
+        show();
+    }
+}
+
 void ViewProvider::setBodyMode(bool bodymode) {
 
     std::vector<App::Property*> props;
@@ -331,8 +430,6 @@ ViewProviderBody* ViewProvider::getBodyViewProvider() {
     return nullptr;
 }
 
-
-
 namespace Gui {
 /// @cond DOXERR
 PROPERTY_SOURCE_TEMPLATE(PartDesignGui::ViewProviderPython, PartDesignGui::ViewProvider)

src/Mod/PartDesign/Gui/ViewProvider.h

@@ -24,12 +24,16 @@
 #ifndef PARTGUI_ViewProvider_H
 #define PARTGUI_ViewProvider_H
 
-#include <Mod/Part/Gui/ViewProvider.h>
-#include "ViewProviderBody.h"
+#include <App/DocumentObject.h>
 #include <Gui/ViewProviderFeaturePython.h>
-#include "Gui/ViewProviderSuppressibleExtension.h"
-
+#include <Gui/ViewProviderSuppressibleExtension.h>
+#include <Mod/Part/Gui/ViewProvider.h>
 #include <Mod/Part/Gui/ViewProviderAttachExtension.h>
+#include <Mod/Part/Gui/ViewProviderPreviewExtension.h>
+#include <Mod/PartDesign/App/Feature.h>
+
+#include "ViewProviderBody.h"
+
 
 namespace PartDesignGui {
 
@@ -40,7 +44,8 @@ class TaskDlgFeatureParameters;
  */
 class PartDesignGuiExport ViewProvider : public PartGui::ViewProviderPart,
                                          Gui::ViewProviderSuppressibleExtension,
-                                         PartGui::ViewProviderAttachExtension
+                                         PartGui::ViewProviderAttachExtension,
+                                         public PartGui::ViewProviderPreviewExtension
 {
     using inherited = PartGui::ViewProviderPart;
     PROPERTY_HEADER_WITH_OVERRIDE(PartDesignGui::ViewProvider);
@@ -51,8 +56,10 @@ public:
     /// destructor
     ~ViewProvider() override;
 
+    void beforeDelete() override;
+    void attach(App::DocumentObject* pcObject) override;
+
     bool doubleClicked() override;
-    void updateData(const App::Property*) override;
     void onChanged(const App::Property* prop) override;
 
     Gui::ViewProvider* startEditing(int ModNum) override;
@@ -73,6 +80,11 @@ public:
     //Returns the ViewProvider of the body the feature belongs to, or NULL, if not in a body
     ViewProviderBody* getBodyViewProvider();
 
+    /// Provides preview shape
+    Part::TopoShape getPreviewShape() const override;
+    /// Toggles visibility of the preview
+    void showPreviousFeature(bool);
+
     PyObject* getPyObject() override;
 
     QIcon mergeColorfulOverlayIcons (const QIcon & orig) const override;
@@ -81,6 +93,10 @@ protected:
     void setupContextMenu(QMenu* menu, QObject* receiver, const char* member) override;
     bool setEdit(int ModNum) override;
     void unsetEdit(int ModNum) override;
+    void updateData(const App::Property* prop) override;
+
+    void attachPreview() override;
+    void updatePreview() override;
 
     bool onDelete(const std::vector<std::string> &) override;
 
@@ -92,7 +108,11 @@ protected:
 
     std::string oldWb;
     ViewProvider* previouslyShownViewProvider { nullptr };
+
     bool isSetTipIcon { false };
+
+private:
+    Gui::CoinPtr<PartGui::SoPreviewShape> pcToolPreview;
 };
 
 using ViewProviderPython = Gui::ViewProviderFeaturePythonT<ViewProvider>;

src/Mod/PartDesign/Gui/ViewProviderAddSub.cpp

@@ -1,261 +0,0 @@
-/***************************************************************************
- *   Copyright (c) 2015 Stefan Tröger <stefantroeger@gmx.net>              *
- *                                                                         *
- *   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 <Inventor/nodes/SoSeparator.h>
-# include <Inventor/nodes/SoSwitch.h>
-# include <Inventor/nodes/SoCoordinate3.h>
-# include <Inventor/nodes/SoNormal.h>
-# include <Inventor/nodes/SoMaterial.h>
-# include <Inventor/nodes/SoPickStyle.h>
-# include <Bnd_Box.hxx>
-# include <BRep_Tool.hxx>
-# include <BRepBndLib.hxx>
-# include <BRepMesh_IncrementalMesh.hxx>
-# include <Standard_Version.hxx>
-# include <TopExp_Explorer.hxx>
-# include <TopoDS.hxx>
-#endif
-
-#include <Base/Console.h>
-#include <Base/Tools.h>
-#include <Gui/Application.h>
-#include <Mod/Part/App/Tools.h>
-#include <Mod/Part/Gui/SoBrepFaceSet.h>
-#include <Mod/PartDesign/App/FeatureAddSub.h>
-
-#include "ViewProviderAddSub.h"
-
-
-using namespace PartDesignGui;
-
-PROPERTY_SOURCE(PartDesignGui::ViewProviderAddSub,PartDesignGui::ViewProvider)
-
-ViewProviderAddSub::ViewProviderAddSub()
-{
-    previewShape = new SoSeparator();
-    previewShape->ref();
-    previewFaceSet = new PartGui::SoBrepFaceSet();
-    previewFaceSet->ref();
-    previewCoords = new SoCoordinate3();
-    previewCoords->ref();
-    previewNorm = new SoNormal();
-    previewNorm->ref();
-    whichChild = -1;
-}
-
-ViewProviderAddSub::~ViewProviderAddSub()
-{
-    previewFaceSet->unref();
-    previewCoords->unref();
-    previewNorm->unref();
-    previewShape->unref();
-}
-
-void ViewProviderAddSub::attach(App::DocumentObject* obj) {
-
-    ViewProvider::attach(obj);
-
-    auto* bind = new SoMaterialBinding();
-    bind->value = SoMaterialBinding::OVERALL;
-    auto* material = new SoMaterial();
-    if (static_cast<PartDesign::FeatureAddSub*>(obj)->getAddSubType() == PartDesign::FeatureAddSub::Additive)
-        material->diffuseColor = SbColor(1,1,0);
-    else
-        material->diffuseColor = SbColor(1,0,0);
-
-    material->transparency = 0.7f;
-    auto* pick = new SoPickStyle();
-    pick->style = SoPickStyle::UNPICKABLE;
-
-    previewShape->addChild(pick);
-    previewShape->addChild(bind);
-    previewShape->addChild(material);
-    previewShape->addChild(previewCoords);
-    previewShape->addChild(previewNorm);
-    previewShape->addChild(previewFaceSet);
-
-    addDisplayMaskMode(previewShape, "Shape preview");
-    updateAddSubShapeIndicator();
-}
-
-void ViewProviderAddSub::updateAddSubShapeIndicator() {
-
-    TopoDS_Shape cShape(getObject<PartDesign::FeatureAddSub>()->AddSubShape.getValue());
-    if (cShape.IsNull()) {
-        previewCoords  ->point      .setNum(0);
-        previewNorm    ->vector     .setNum(0);
-        previewFaceSet ->coordIndex .setNum(0);
-        previewFaceSet ->partIndex  .setNum(0);
-        return;
-    }
-
-    try {
-        // calculating the deflection value
-        Bnd_Box bounds;
-        BRepBndLib::Add(cShape, bounds);
-        bounds.SetGap(0.0);
-        Standard_Real xMin, yMin, zMin, xMax, yMax, zMax;
-        bounds.Get(xMin, yMin, zMin, xMax, yMax, zMax);
-        Standard_Real deflection = ((xMax-xMin)+(yMax-yMin)+(zMax-zMin))/300.0 * Deviation.getValue();
-
-        // create or use the mesh on the data structure
-        Standard_Real AngDeflectionRads = Base::toRadians(AngularDeflection.getValue());
-        BRepMesh_IncrementalMesh(cShape, deflection, Standard_False, AngDeflectionRads, Standard_True);
-
-        // We must reset the location here because the transformation data
-        // are set in the placement property
-        TopLoc_Location aLoc;
-        cShape.Location(aLoc);
-
-        // count triangles and nodes in the mesh
-        int numTriangles=0,numNodes=0,numNorms=0,numFaces=0;
-        TopExp_Explorer Ex;
-        for (Ex.Init(cShape,TopAbs_FACE);Ex.More();Ex.Next()) {
-            Handle (Poly_Triangulation) mesh = BRep_Tool::Triangulation(TopoDS::Face(Ex.Current()), aLoc);
-            // Note: we must also count empty faces
-            if (!mesh.IsNull()) {
-                numTriangles += mesh->NbTriangles();
-                numNodes     += mesh->NbNodes();
-                numNorms     += mesh->NbNodes();
-            }
-            numFaces++;
-        }
-
-        // create memory for the nodes and indexes
-        previewCoords  ->point      .setNum(numNodes);
-        previewNorm    ->vector     .setNum(numNorms);
-        previewFaceSet ->coordIndex .setNum(numTriangles*4);
-        previewFaceSet ->partIndex  .setNum(numFaces);
-
-        // get the raw memory for fast fill up
-        SbVec3f* verts = previewCoords      ->point      .startEditing();
-        SbVec3f* previewNorms = previewNorm ->vector     .startEditing();
-        int32_t* index = previewFaceSet     ->coordIndex .startEditing();
-        int32_t* parts = previewFaceSet     ->partIndex  .startEditing();
-
-        // preset the previewNormal vector with null vector
-        for (int i=0;i < numNorms;i++)
-            previewNorms[i]= SbVec3f(0.0,0.0,0.0);
-
-        int ii = 0,faceNodeOffset=0,faceTriaOffset=0;
-        for (Ex.Init(cShape, TopAbs_FACE); Ex.More(); Ex.Next(),ii++) {
-            const TopoDS_Face &actFace = TopoDS::Face(Ex.Current());
-
-            TopLoc_Location loc;
-            Handle(Poly_Triangulation) mesh = BRep_Tool::Triangulation(actFace, loc);
-            if (mesh.IsNull())
-                continue;
-
-            // get triangulation
-            std::vector<gp_Pnt> points;
-            std::vector<Poly_Triangle> facets;
-            Part::Tools::getTriangulation(actFace, points, facets);
-
-            // get normal per vertex
-            std::vector<gp_Vec> vertexnormals;
-            Part::Tools::getPointNormals(actFace, mesh, vertexnormals);
-            Part::Tools::applyTransformationOnNormals(loc, vertexnormals);
-
-            // getting size of node and triangle array of this face
-            std::size_t nbNodesInFace = points.size();
-            std::size_t nbTriInFace   = facets.size();
-
-            for (std::size_t i = 0; i < points.size(); i++) {
-                verts[faceNodeOffset+i] = SbVec3f(points[i].X(), points[i].Y(), points[i].Z());
-            }
-
-            for (std::size_t i = 0; i < vertexnormals.size(); i++) {
-                previewNorms[faceNodeOffset+i] = SbVec3f(vertexnormals[i].X(), vertexnormals[i].Y(), vertexnormals[i].Z());
-            }
-
-            // cycling through the poly mesh
-            for (std::size_t g=0; g < nbTriInFace; g++) {
-                // Get the triangle
-                Standard_Integer N1,N2,N3;
-                facets[g].Get(N1,N2,N3);
-
-                // set the index vector with the 3 point indexes and the end delimiter
-                index[faceTriaOffset*4+4*g]   = faceNodeOffset+N1;
-                index[faceTriaOffset*4+4*g+1] = faceNodeOffset+N2;
-                index[faceTriaOffset*4+4*g+2] = faceNodeOffset+N3;
-                index[faceTriaOffset*4+4*g+3] = SO_END_FACE_INDEX;
-            }
-
-            parts[ii] = nbTriInFace; // new part
-
-            // counting up the per Face offsets
-            faceNodeOffset += nbNodesInFace;
-            faceTriaOffset += nbTriInFace;
-        }
-
-        // previewNormalize all previewNormals
-        for (int i = 0; i< numNorms ;i++)
-            previewNorms[i].normalize();
-
-        // end the editing of the nodes
-        previewCoords  ->point       .finishEditing();
-        previewNorm    ->vector      .finishEditing();
-        previewFaceSet ->coordIndex  .finishEditing();
-        previewFaceSet ->partIndex   .finishEditing();
-    }
-    catch (...) {
-        Base::Console().error("Cannot compute Inventor representation for the shape of %s.\n",pcObject->getNameInDocument());
-    }
-}
-
-void ViewProviderAddSub::updateData(const App::Property* p) {
-
-    if(p->getName() && strcmp(p->getName(), "AddSubShape")==0)
-        updateAddSubShapeIndicator();
-
-    PartDesignGui::ViewProvider::updateData(p);
-}
-
-void ViewProviderAddSub::setPreviewDisplayMode(bool onoff) {
-    // A mask mode is always set, also for hidden objects.
-    // Now when changing to another mask mode this automatically
-    // displays an object and when restoring the previous state it's
-    // not sufficient to only revert the mask mode. Also the child
-    // number of the switch node must be reverted.
-    if (onoff) {
-        if(pcModeSwitch->getChild(getDefaultMode()) == previewShape)
-            return;
-        displayMode = getActiveDisplayMode();
-        whichChild = pcModeSwitch->whichChild.getValue();
-        setDisplayMaskMode("Shape preview");
-    }
-
-    if (!onoff) {
-        if(pcModeSwitch->getChild(getDefaultMode()) != previewShape)
-            return;
-        setDisplayMaskMode(displayMode.c_str());
-        pcModeSwitch->whichChild.setValue(whichChild);
-    }
-
-    App::DocumentObject* obj = getObject<PartDesign::Feature>()->BaseFeature.getValue();
-    if (obj)
-        static_cast<PartDesignGui::ViewProvider*>(Gui::Application::Instance->getViewProvider(obj))->makeTemporaryVisible(onoff);
-}

src/Mod/PartDesign/Gui/ViewProviderAddSub.h

@@ -1,62 +0,0 @@
-/***************************************************************************
- *   Copyright (c) 2015 Stefan Tröger <stefantroeger@gmx.net>              *
- *                                                                         *
- *   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                                *
- *                                                                         *
- ***************************************************************************/
-
-
-#ifndef PARTGUI_ViewProviderAddSub_H
-#define PARTGUI_ViewProviderAddSub_H
-
-#include "ViewProvider.h"
-#include <Mod/Part/Gui/SoBrepFaceSet.h>
-
-namespace PartDesignGui {
-
-class PartDesignGuiExport ViewProviderAddSub : public ViewProvider
-{
-    PROPERTY_HEADER_WITH_OVERRIDE(PartDesignGui::ViewProviderAddSub);
-
-public:
-    /// constructor
-    ViewProviderAddSub();
-    /// destructor
-    ~ViewProviderAddSub() override;
-
-    void attach(App::DocumentObject*) override;
-    void updateData(const App::Property*) override;
-
-protected:
-    void updateAddSubShapeIndicator();
-    void setPreviewDisplayMode(bool);
-
-    SoSeparator*                previewShape;
-    PartGui::SoBrepFaceSet*     previewFaceSet;
-    SoCoordinate3*              previewCoords;
-    SoNormal*                   previewNorm;
-
-private:
-    int                         whichChild;
-    std::string                 displayMode;
-};
-
-} // namespace PartDesignGui
-
-
-#endif // PARTGUI_ViewProviderBoolean_H

src/Mod/PartDesign/Gui/ViewProviderDressUp.cpp

@@ -39,11 +39,23 @@
 #include "ViewProviderDressUp.h"
 #include "TaskDressUpParameters.h"
 
+#include <Gui/Utilities.h>
+
 using namespace PartDesignGui;
 
-PROPERTY_SOURCE(PartDesignGui::ViewProviderDressUp,PartDesignGui::ViewProvider)
+PROPERTY_SOURCE(PartDesignGui::ViewProviderDressUp, PartDesignGui::ViewProvider)
 
 
+void ViewProviderDressUp::attach(App::DocumentObject* pcObject)
+{
+    ViewProvider::attach(pcObject);
+
+    const Base::Color magenta(1.0F, 0.0F, 1.0F);
+    PreviewColor.setValue(magenta);
+
+    setErrorState(false);
+}
+
 void ViewProviderDressUp::setupContextMenu(QMenu* menu, QObject* receiver, const char* member)
 {
     QString text = QString::fromStdString(getObject()->Label.getStrValue());
@@ -121,3 +133,13 @@ void ViewProviderDressUp::highlightReferences(const bool on)
     }
 }
 
+void ViewProviderDressUp::setErrorState(bool error)
+{
+    const Base::Color red(1.0, 0.0, 0.0);
+
+    constexpr float errorTransparency = 0.95F;
+
+    pcPreviewShape->transparency = error ? errorTransparency : PartGui::SoPreviewShape::defaultTransparency;
+    pcPreviewShape->color = Base::convertTo<SbColor>(error ? red : PreviewColor.getValue());
+}
+

src/Mod/PartDesign/Gui/ViewProviderDressUp.h

@@ -40,7 +40,9 @@ public:
     /// constructor
     ViewProviderDressUp()  = default;
     /// destructor
-    ~ViewProviderDressUp() override         = default;
+    ~ViewProviderDressUp() override = default;
+
+    void attach(App::DocumentObject* pcObject) override;
 
     /// grouping handling
     void setupContextMenu(QMenu*, QObject*, const char*) override;
@@ -48,6 +50,9 @@ public:
     /// Highlight the references that have been selected
     void highlightReferences(const bool on);
 
+    /// Set preview parameters to indicate error state
+    void setErrorState(bool error);
+
     /**
      * Returns the feature Name associated with the view provider.
      * Should be reimplemented in the successor.

src/Mod/PartDesign/Gui/ViewProviderHelix.cpp

@@ -49,12 +49,12 @@ ViewProviderHelix::~ViewProviderHelix() = default;
 void ViewProviderHelix::setupContextMenu(QMenu* menu, QObject* receiver, const char* member)
 {
     addDefaultAction(menu, QObject::tr("Edit Helix"));
-    PartDesignGui::ViewProviderAddSub::setupContextMenu(menu, receiver, member);
+    ViewProvider::setupContextMenu(menu, receiver, member);
 }
 
 TaskDlgFeatureParameters *ViewProviderHelix::getEditDialog()
 {
-    return new TaskDlgHelixParameters( this );
+    return new TaskDlgHelixParameters(this);
 }
 
 QIcon ViewProviderHelix::getIcon() const {
@@ -69,23 +69,6 @@ QIcon ViewProviderHelix::getIcon() const {
     return PartDesignGui::ViewProvider::mergeGreyableOverlayIcons(Gui::BitmapFactory().pixmap(str.toStdString().c_str()));
 }
 
-bool ViewProviderHelix::setEdit(int ModNum)
-{
-    if (ModNum == ViewProvider::Default ) {
-        auto* prim = getObject<PartDesign::Helix>();
-        setPreviewDisplayMode(TaskHelixParameters::showPreview(prim));
-    }
-    return ViewProviderAddSub::setEdit(ModNum);
-}
-
-void ViewProviderHelix::unsetEdit(int ModNum)
-{
-    setPreviewDisplayMode(false);
-    // Rely on parent class to:
-    // restitute old workbench (set setEdit above) and close the dialog if exiting editing
-    PartDesignGui::ViewProvider::unsetEdit(ModNum);
-}
-
 std::vector<App::DocumentObject*> ViewProviderHelix::claimChildren() const {
     std::vector<App::DocumentObject*> temp;
     App::DocumentObject* sketch = getObject<PartDesign::ProfileBased>()->Profile.getValue();

src/Mod/PartDesign/Gui/ViewProviderHelix.h

@@ -24,12 +24,12 @@
 #ifndef PARTGUI_ViewProviderHelix_H
 #define PARTGUI_ViewProviderHelix_H
 
-#include "ViewProviderAddSub.h"
+#include "ViewProvider.h"
 
 
 namespace PartDesignGui {
 
-class PartDesignGuiExport ViewProviderHelix : public ViewProviderAddSub
+class PartDesignGuiExport ViewProviderHelix : public ViewProvider
 {
     PROPERTY_HEADER_WITH_OVERRIDE(PartDesignGui::ViewProviderHelix);
 
@@ -51,8 +51,6 @@ protected:
 
     /// Returns a newly created TaskDlgHelixParameters
     TaskDlgFeatureParameters *getEditDialog() override;
-    bool  setEdit(int ModNum) override;
-    void unsetEdit(int ModNum) override;
 };
 
 

src/Mod/PartDesign/Gui/ViewProviderHole.cpp

@@ -63,59 +63,24 @@ void ViewProviderHole::setupContextMenu(QMenu* menu, QObject* receiver, const ch
     PartGui::ViewProviderPart::setupContextMenu(menu, receiver, member); // clazy:exclude=skipped-base-method
 }
 
-bool ViewProviderHole::setEdit(int ModNum)
-{
-    if (ModNum == ViewProvider::Default ) {
-        // When double-clicking on the item for this hole the
-        // object unsets and sets its edit mode without closing
-        // the task panel
-        Gui::TaskView::TaskDialog *dlg = Gui::Control().activeDialog();
-        TaskDlgHoleParameters *holeDlg = qobject_cast<TaskDlgHoleParameters *>(dlg);
-        if (holeDlg && holeDlg->getViewObject() != this)
-            holeDlg = nullptr; // another hole left open its task panel
-        if (dlg && !holeDlg) {
-            QMessageBox msgBox(Gui::getMainWindow());
-            msgBox.setText(QObject::tr("A dialog is already open in the task panel"));
-            msgBox.setInformativeText(QObject::tr("Close this dialog?"));
-            msgBox.setStandardButtons(QMessageBox::Yes | QMessageBox::No);
-            msgBox.setDefaultButton(QMessageBox::Yes);
-            int ret = msgBox.exec();
-            if (ret == QMessageBox::Yes)
-                Gui::Control().closeDialog();
-            else
-                return false;
-        }
-
-        // clear the selection (convenience)
-        Gui::Selection().clearSelection();
-
-        // always change to PartDesign WB, remember where we come from
-        oldWb = Gui::Command::assureWorkbench("PartDesignWorkbench");
-
-        // start the edit dialog
-        if (holeDlg)
-            Gui::Control().showDialog(holeDlg);
-        else
-            Gui::Control().showDialog(new TaskDlgHoleParameters(this));
-
-        return true;
-    }
-    else {
-        return PartGui::ViewProviderPart::setEdit(ModNum); // clazy:exclude=skipped-base-method
-    }
-}
-
-bool ViewProviderHole::onDelete(const std::vector<std::string> &s)
+bool ViewProviderHole::onDelete(const std::vector<std::string>& s)
 {
     // get the Sketch
     PartDesign::Hole* pcHole = getObject<PartDesign::Hole>();
-    Sketcher::SketchObject *pcSketch = nullptr;
-    if (pcHole->Profile.getValue())
+    Sketcher::SketchObject* pcSketch = nullptr;
+    if (pcHole->Profile.getValue()) {
         pcSketch = static_cast<Sketcher::SketchObject*>(pcHole->Profile.getValue());
+    }
 
     // if abort command deleted the object the sketch is visible again
-    if (pcSketch && Gui::Application::Instance->getViewProvider(pcSketch))
+    if (pcSketch && Gui::Application::Instance->getViewProvider(pcSketch)) {
         Gui::Application::Instance->getViewProvider(pcSketch)->show();
+    }
 
     return ViewProvider::onDelete(s);
 }
+
+TaskDlgFeatureParameters* ViewProviderHole::getEditDialog()
+{
+    return new TaskDlgHoleParameters(this);
+}

src/Mod/PartDesign/Gui/ViewProviderHole.h

@@ -43,8 +43,9 @@ public:
     std::vector<App::DocumentObject*> claimChildren()const override;
     void setupContextMenu(QMenu *menu, QObject *receiver, const char *member) override;
     bool onDelete(const std::vector<std::string> &s) override;
+
 protected:
-    bool setEdit(int ModNum) override;
+    TaskDlgFeatureParameters* getEditDialog() override;
 };
 
 

src/Mod/PartDesign/Gui/ViewProviderLoft.cpp

@@ -37,7 +37,7 @@
 
 using namespace PartDesignGui;
 
-PROPERTY_SOURCE(PartDesignGui::ViewProviderLoft,PartDesignGui::ViewProvider)
+PROPERTY_SOURCE(PartDesignGui::ViewProviderLoft, PartDesignGui::ViewProvider)
 
 ViewProviderLoft::ViewProviderLoft() = default;
 
@@ -64,28 +64,13 @@ std::vector<App::DocumentObject*> ViewProviderLoft::claimChildren()const
 void ViewProviderLoft::setupContextMenu(QMenu* menu, QObject* receiver, const char* member)
 {
     addDefaultAction(menu, QObject::tr("Edit Loft"));
-    PartDesignGui::ViewProvider::setupContextMenu(menu, receiver, member);
-}
-
-bool ViewProviderLoft::setEdit(int ModNum)
-{
-    if (ModNum == ViewProvider::Default)
-        setPreviewDisplayMode(true);
-
-    return ViewProviderAddSub::setEdit(ModNum);
+    ViewProvider::setupContextMenu(menu, receiver, member);
 }
 
 TaskDlgFeatureParameters* ViewProviderLoft::getEditDialog() {
     return new TaskDlgLoftParameters(this);
 }
 
-
-void ViewProviderLoft::unsetEdit(int ModNum) {
-    setPreviewDisplayMode(false);
-    ViewProviderAddSub::unsetEdit(ModNum);
-}
-
-
 bool ViewProviderLoft::onDelete(const std::vector<std::string> & /*s*/)
 {/*
     PartDesign::Loft* pcLoft = getObject<PartDesign::Loft>();

src/Mod/PartDesign/Gui/ViewProviderLoft.h

@@ -24,11 +24,11 @@
 #ifndef PARTGUI_ViewProviderLoft_H
 #define PARTGUI_ViewProviderLoft_H
 
-#include "ViewProviderAddSub.h"
+#include "ViewProvider.h"
 
 namespace PartDesignGui {
 
-class PartDesignGuiExport ViewProviderLoft : public ViewProviderAddSub
+class PartDesignGuiExport ViewProviderLoft : public ViewProvider
 {
     PROPERTY_HEADER_WITH_OVERRIDE(PartDesignGui::ViewProviderLoft);
 
@@ -55,8 +55,6 @@ public:
 
 protected:
     QIcon getIcon() const override;
-    bool setEdit(int ModNum) override;
-    void unsetEdit(int ModNum) override;
     TaskDlgFeatureParameters* getEditDialog() override;
 
 private:

src/Mod/PartDesign/Gui/ViewProviderPipe.cpp

@@ -75,19 +75,6 @@ void ViewProviderPipe::setupContextMenu(QMenu* menu, QObject* receiver, const ch
     PartDesignGui::ViewProvider::setupContextMenu(menu, receiver, member);
 }
 
-bool ViewProviderPipe::setEdit(int ModNum) {
-    if (ModNum == ViewProvider::Default )
-        setPreviewDisplayMode(true);
-
-    return PartDesignGui::ViewProvider::setEdit(ModNum);
-}
-
-void ViewProviderPipe::unsetEdit(int ModNum) {
-    setPreviewDisplayMode(false);
-    PartDesignGui::ViewProvider::unsetEdit(ModNum);
-}
-
-
 TaskDlgFeatureParameters* ViewProviderPipe::getEditDialog() {
     return new TaskDlgPipeParameters(this, false);
 }

src/Mod/PartDesign/Gui/ViewProviderPipe.h

@@ -24,11 +24,11 @@
 #ifndef PARTGUI_ViewProviderPipe_H
 #define PARTGUI_ViewProviderPipe_H
 
-#include "ViewProviderAddSub.h"
+#include "ViewProvider.h"
 
 namespace PartDesignGui {
 
-class PartDesignGuiExport ViewProviderPipe : public ViewProviderAddSub
+class PartDesignGuiExport ViewProviderPipe : public ViewProvider
 {
     PROPERTY_HEADER_WITH_OVERRIDE(PartDesignGui::ViewProviderPipe);
 
@@ -54,8 +54,6 @@ public:
 
 protected:
     QIcon getIcon() const override;
-    bool setEdit(int ModNum) override;
-    void unsetEdit(int ModNum) override;
 
     /// Returns a newly created TaskDlgPipeParameters
     TaskDlgFeatureParameters *getEditDialog() override;

src/Mod/PartDesign/Gui/ViewProviderPrimitive.cpp

@@ -46,71 +46,15 @@ ViewProviderPrimitive::ViewProviderPrimitive() = default;
 
 ViewProviderPrimitive::~ViewProviderPrimitive() = default;
 
-void ViewProviderPrimitive::attach(App::DocumentObject* obj) {
-    ViewProviderAddSub::attach(obj);
-}
-
 void ViewProviderPrimitive::setupContextMenu(QMenu* menu, QObject* receiver, const char* member)
 {
     addDefaultAction(menu, QObject::tr("Edit Primitive"));
     PartDesignGui::ViewProvider::setupContextMenu(menu, receiver, member);
 }
 
-bool ViewProviderPrimitive::setEdit(int ModNum)
+TaskDlgFeatureParameters* ViewProviderPrimitive::getEditDialog()
 {
-    if (ModNum == ViewProvider::Default ) {
-        // When double-clicking on the item for this fillet the
-        // object unsets and sets its edit mode without closing
-        // the task panel
-        Gui::TaskView::TaskDialog *dlg = Gui::Control().activeDialog();
-        TaskPrimitiveParameters *primitiveDlg = qobject_cast<TaskPrimitiveParameters *>(dlg);
-        if (dlg && !primitiveDlg) {
-            QMessageBox msgBox(Gui::getMainWindow());
-            msgBox.setText(QObject::tr("A dialog is already open in the task panel"));
-            msgBox.setInformativeText(QObject::tr("Close this dialog?"));
-            msgBox.setStandardButtons(QMessageBox::Yes | QMessageBox::No);
-            msgBox.setDefaultButton(QMessageBox::Yes);
-            int ret = msgBox.exec();
-            if (ret == QMessageBox::Yes)
-                Gui::Control().closeDialog();
-            else
-                return false;
-        }
-
-        // clear the selection (convenience)
-        Gui::Selection().clearSelection();
-
-        // always change to PartDesign WB, remember where we come from
-        oldWb = Gui::Command::assureWorkbench("PartDesignWorkbench");
-
-        // start the edit dialog
-        // another pad left open its task panel
-        if (primitiveDlg)
-            Gui::Control().showDialog(primitiveDlg);
-        else
-            Gui::Control().showDialog(new TaskPrimitiveParameters(this));
-
-        setPreviewDisplayMode(true);
-
-        return true;
-    }
-    else {
-        return ViewProviderAddSub::setEdit(ModNum);
-    }
-}
-
-void ViewProviderPrimitive::unsetEdit(int ModNum)
-{
-    setPreviewDisplayMode(false);
-
-    // Rely on parent class to:
-    // restitute old workbench (set setEdit above) and close the dialog if exiting editing
-    PartDesignGui::ViewProvider::unsetEdit(ModNum);
-
-}
-
-void ViewProviderPrimitive::updateData(const App::Property* p) {
-    PartDesignGui::ViewProviderAddSub::updateData(p);
+    return new TaskDlgPrimitiveParameters(this);
 }
 
 QIcon ViewProviderPrimitive::getIcon() const {

src/Mod/PartDesign/Gui/ViewProviderPrimitive.h

@@ -24,11 +24,11 @@
 #ifndef PARTGUI_ViewProviderPrimitive_H
 #define PARTGUI_ViewProviderPrimitive_H
 
-#include "ViewProviderAddSub.h"
+#include "ViewProvider.h"
 
 namespace PartDesignGui {
 
-class PartDesignGuiExport ViewProviderPrimitive : public ViewProviderAddSub
+class PartDesignGuiExport ViewProviderPrimitive : public ViewProvider
 {
     PROPERTY_HEADER_WITH_OVERRIDE(PartDesignGui::ViewProviderPrimitive);
 
@@ -38,16 +38,11 @@ public:
     /// destructor
     ~ViewProviderPrimitive() override;
 
-    void attach(App::DocumentObject*) override;
-    void updateData(const App::Property*) override;
-
 protected:
     QIcon getIcon() const override;
     void setupContextMenu(QMenu* menu, QObject* receiver, const char* member) override;
-    bool  setEdit(int ModNum) override;
-    void unsetEdit(int ModNum) override;
 
-    void updateAddSubShapeIndicator();
+    TaskDlgFeatureParameters *getEditDialog() override;
 
     std::string                 displayMode;
 };

src/Mod/PartDesign/Gui/ViewProviderSketchBased.h

@@ -23,7 +23,7 @@
 #ifndef VIEWPROVIDERSKETCHBASED_H_QKP3UG9A
 #define VIEWPROVIDERSKETCHBASED_H_QKP3UG9A
 
-#include "ViewProviderAddSub.h"
+#include "ViewProvider.h"
 
 namespace PartDesignGui {
 
@@ -41,7 +41,7 @@ public:
     ~ViewProviderSketchBased() override;
 
     /// grouping handling
-    std::vector<App::DocumentObject*> claimChildren()const override;
+    std::vector<App::DocumentObject*> claimChildren() const override;
 
     bool onDelete(const std::vector<std::string> &) override;