From 3bccd6686a72d1c5c19beaf65ec67a8766064340 Mon Sep 17 00:00:00 2001
From: Ajinkya Dahale <AjinkyaDahale@users.noreply.github.com>
Date: Thu, 22 Dec 2022 01:08:49 +0530
Subject: [PATCH] [Sketcher] Do not use `TangentViaPoint` for tangent-at-knot

---
 src/Mod/Sketcher/App/Sketch.cpp             | 27 ++++++++++----------
 src/Mod/Sketcher/Gui/CommandConstraints.cpp | 28 +--------------------
 2 files changed, 14 insertions(+), 41 deletions(-)

diff --git a/src/Mod/Sketcher/App/Sketch.cpp b/src/Mod/Sketcher/App/Sketch.cpp
index 8ac5eeb150..06547a6e2a 100644
--- a/src/Mod/Sketcher/App/Sketch.cpp
+++ b/src/Mod/Sketcher/App/Sketch.cpp
@@ -1722,27 +1722,26 @@ int Sketch::addConstraint(const Constraint *constraint)
             //simple tangency
             rtn = addTangentConstraint(constraint->First,constraint->Second);
         }
-        else {
+        else if (constraint->FirstPos == PointPos::start &&
+                 constraint->SecondPos == PointPos::none &&
+                 constraint->Third == GeoEnum::GeoUndef) {
             // check for B-Spline Knot to curve tangency
-            if (constraint->FirstPos == PointPos::none &&
-                constraint->SecondPos == PointPos::none &&
-                constraint->ThirdPos == PointPos::start) {
-                auto knotgeoId = checkGeoId(constraint->Third);
-                if (Geoms[knotgeoId].type == Point) {
-                    auto *point = static_cast<const GeomPoint*>(Geoms[knotgeoId].geo);
+            auto knotgeoId = checkGeoId(constraint->First);
+            if (Geoms[knotgeoId].type == Point) {
+                auto *point = static_cast<const GeomPoint*>(Geoms[knotgeoId].geo);
 
-                    if (GeometryFacade::isInternalType(point,InternalType::BSplineKnotPoint)) {
-                        auto bsplinegeoid = internalAlignmentGeometryMap.at(constraint->Third);
+                if (GeometryFacade::isInternalType(point,InternalType::BSplineKnotPoint)) {
+                    auto bsplinegeoid = internalAlignmentGeometryMap.at(constraint->First);
 
-                        bsplinegeoid = checkGeoId(bsplinegeoid);
+                    bsplinegeoid = checkGeoId(bsplinegeoid);
 
-                        auto linegeoid = checkGeoId(constraint->Second);
+                    auto linegeoid = checkGeoId(constraint->Second);
 
-                        return addTangentLineAtBSplineKnotConstraint(linegeoid, bsplinegeoid, knotgeoId);
-                    }
+                    rtn = addTangentLineAtBSplineKnotConstraint(linegeoid, bsplinegeoid, knotgeoId);
                 }
             }
-
+        }
+        else {
             //any other point-wise tangency (endpoint-to-curve, endpoint-to-endpoint, tangent-via-point)
             c.value = new double(constraint->getValue());
             if(c.driving)
diff --git a/src/Mod/Sketcher/Gui/CommandConstraints.cpp b/src/Mod/Sketcher/Gui/CommandConstraints.cpp
index ec3e50a336..4e5e680b18 100644
--- a/src/Mod/Sketcher/Gui/CommandConstraints.cpp
+++ b/src/Mod/Sketcher/Gui/CommandConstraints.cpp
@@ -4226,33 +4226,7 @@ void CmdSketcherConstrainTangent::activated(int iMsg)
             }
 
             if (isSimpleVertex(Obj, GeoId1, PosId1)) {
-                if (isBsplineKnot(Obj, GeoId1)) {
-                    // find the B-spline and treat as TangentViaPoint
-                    openCommand(QT_TRANSLATE_NOOP("Command", "Add tangent constraint"));
-                    const std::vector<Constraint *> &constraints = Obj->Constraints.getValues();
-                    for (const auto& constraint: constraints) {
-                        // TODO: wrap around with try-catch
-                        if (constraint->Type == Sketcher::ConstraintType::InternalAlignment &&
-                            constraint->First == GeoId1 &&
-                            constraint->AlignmentType == Sketcher::InternalAlignmentType::BSplineKnotPoint) {
-                            int GeoId3 = constraint->Second;
-                            // TODO: ensure C1 continuity at point
-                            if(! IsPointAlreadyOnCurve(GeoId2, GeoId1, PosId1, Obj)){
-                                Gui::cmdAppObjectArgs(selection[0].getObject(), "addConstraint(Sketcher.Constraint('PointOnObject',%d,%d,%d)) ",
-                                                      GeoId1,static_cast<int>(PosId1),GeoId2);
-                            }
-
-                            Gui::cmdAppObjectArgs(selection[0].getObject(), "addConstraint(Sketcher.Constraint('TangentViaPoint',%d,%d,%d,%d)) ",
-                                                  GeoId3,GeoId2,GeoId1,static_cast<int>(PosId1));
-                            commitCommand();
-                            tryAutoRecompute(Obj);
-
-                            getSelection().clearSelection();
-                            return;
-                        }
-                    }
-                }
-                else {
+                if (!isBsplineKnot(Obj, GeoId1)) {
                     QMessageBox::warning(Gui::getMainWindow(), QObject::tr("Wrong selection"),
                                          QObject::tr("Cannot add a tangency constraint at an unconnected point!"));
                     return;