PD: fix gizmo direction when the calculated point lies outside the face (#26616)

* PD: fix gizmo direction when the calculated point lies outside the face

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

---------

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

src/Mod/Part/App/GizmoHelper.cpp

@@ -43,23 +43,24 @@
 
 EdgeMidPointProps getEdgeMidPointProps(Part::TopoShape& edge)
 {
-    std::unique_ptr<Part::Geometry> geom = Part::Geometry::fromShape(edge.getShape());
-    auto curve = freecad_cast<Part::GeomCurve*>(geom.get());
-    double u1 = curve->getFirstParameter();
-    double u2 = curve->getLastParameter();
-    double middle = (u1 + u2) / 2;
-    Base::Vector3d position = curve->pointAtParameter(middle);
+    double u1, u2;
+    TopoDS_Edge TDSEdge = TopoDS::Edge(edge.getShape());
+    Handle(Geom_Curve) curve = BRep_Tool::Curve(TDSEdge, u1, u2);
+    double middle = (u1 + u2) / 2.0;
 
-    Base::Vector3d tangent;
-    bool ret = curve->tangent(middle, tangent);
-    if (ret) {
-        return {position, tangent, middle};
+    gp_Pnt pos;
+    gp_Vec derivative;
+    curve->D1(middle, pos, derivative);
+
+    auto position = Base::convertTo<Base::Vector3d>(pos);
+    auto tangent = Base::convertTo<Base::Vector3d>(derivative);
+    tangent.Normalize();
+
+    if (TDSEdge.Orientation() == TopAbs_REVERSED) {
+        tangent = -tangent;
     }
 
-    Base::Console().error(
-        "Failed to calculate tangent for the draggers! Please file a bug report for this."
-    );
-    return {position, Base::Vector3d {0, 0, 0}, middle};
+    return {position, tangent, middle};
 }
 
 Base::Vector3d getCentreOfMassFromFace(TopoDS_Face& face)
@@ -69,30 +70,41 @@ Base::Vector3d getCentreOfMassFromFace(TopoDS_Face& face)
     return Base::convertTo<Base::Vector3d>(massProps.CentreOfMass());
 }
 
-std::optional<std::pair<Base::Vector3d, Base::Vector3d>> getFaceNormalFromPointNearEdge(
+PointOnFaceNearEdgeProps getFaceNormalFromPointNearEdge(
     Part::TopoShape& edge,
     double middle,
     TopoDS_Face& face
 )
 {
-    auto _edge = TopoDS::Edge(edge.getShape());
+    auto TDSedge = TopoDS::Edge(edge.getShape());
 
-    gp_Pnt _inwardPoint;
-    gp_Dir _normal;
+    gp_Pnt inwardPoint;
+    gp_Pnt2d inwardPoint2d;
+    gp_Dir normal;
     Handle(IntTools_Context) context = new IntTools_Context;
 
-    if (!BOPTools_AlgoTools3D::GetApproxNormalToFaceOnEdge(
-            _edge,
-            face,
-            middle,
-            _inwardPoint,
-            _normal,
-            context
-        )) {
-        return std::nullopt;
+    int res
+        = BOPTools_AlgoTools3D::PointNearEdge(TDSedge, face, middle, inwardPoint2d, inwardPoint, context);
+
+    PointOnFaceNearEdgeProps props;
+    switch (res) {
+        case 0:
+            props.state = PointOnFaceNearEdgeProps::State::OnFace;
+            break;
+        case 2:
+            props.state = PointOnFaceNearEdgeProps::State::OutsideFace;
+            break;
+        default:
+            props.state = PointOnFaceNearEdgeProps::State::Undefined;
+            return props;
     }
 
-    return {{Base::convertTo<Base::Vector3d>(_inwardPoint), Base::convertTo<Base::Vector3d>(_normal)}};
+    BOPTools_AlgoTools3D::GetNormalToFaceOnEdge(TDSedge, face, middle, normal, context);
+
+    props.position = Base::convertTo<Base::Vector3d>(inwardPoint);
+    props.normal = Base::convertTo<Base::Vector3d>(normal);
+
+    return props;
 }
 
 Base::Vector3d getFaceNormalFromPoint(Base::Vector3d& point, TopoDS_Face& face)
@@ -132,9 +144,10 @@ DraggerPlacementProps getDraggerPlacementFromEdgeAndFace(Part::TopoShape& edge,
 
     Base::Vector3d normal;
     Base::Vector3d inwardPoint;
-    if (auto ret = getFaceNormalFromPointNearEdge(edge, middle, face)) {
-        inwardPoint = ret->first;
-        normal = ret->second;
+    auto props = getFaceNormalFromPointNearEdge(edge, middle, face);
+    if (props.state != PointOnFaceNearEdgeProps::State::Undefined) {
+        inwardPoint = props.position;
+        normal = props.normal;
     }
     else {
         // Failed to compute the normal at a point on the face near the edge
@@ -151,13 +164,19 @@ DraggerPlacementProps getDraggerPlacementFromEdgeAndFace(Part::TopoShape& edge,
         dir = -dir;
     }
 
+    // Assumption: Since the point is very close to the edge but lies outside
+    // the face we can reverse the direction to point towards the face material
+    if (props.state == PointOnFaceNearEdgeProps::State::OutsideFace) {
+        dir = -dir;
+    }
+
     return {position, dir, tangent};
 }
 
 DraggerPlacementProps getDraggerPlacementFromEdgeAndFace(Part::TopoShape& edge, Part::TopoShape& face)
 {
-    TopoDS_Face _face = TopoDS::Face(face.getShape());
-    return getDraggerPlacementFromEdgeAndFace(edge, _face);
+    TopoDS_Face TDSFace = TopoDS::Face(face.getShape());
+    return getDraggerPlacementFromEdgeAndFace(edge, TDSFace);
 }
 
 std::vector<Part::TopoShape> getAdjacentEdgesFromFace(Part::TopoShape& face)

src/Mod/Part/App/GizmoHelper.h

@@ -39,7 +39,20 @@ EdgeMidPointProps PartExport getEdgeMidPointProps(Part::TopoShape& edge);
 
 Base::Vector3d PartExport getCentreOfMassFromFace(TopoDS_Face& face);
 
-std::optional<std::pair<Base::Vector3d, Base::Vector3d>> PartExport
+struct PartExport PointOnFaceNearEdgeProps
+{
+    enum class State : std::uint8_t
+    {
+        OnFace,
+        OutsideFace,
+        Undefined
+    };
+
+    Base::Vector3d position;
+    Base::Vector3d normal;
+    State state;
+};
+PointOnFaceNearEdgeProps PartExport
 getFaceNormalFromPointNearEdge(Part::TopoShape& edge, double middle, TopoDS_Face& face);
 
 Base::Vector3d PartExport getFaceNormalFromPoint(Base::Vector3d& point, TopoDS_Face& face);

src/Mod/Part/Gui/TaskThickness.cpp

@@ -361,7 +361,7 @@ void ThicknessWidget::setGizmoPositions()
     }
 
     Part::Thickness* thickness = getObject();
-    auto base = thickness->getTopoShape(
+    auto base = Part::Thickness::getTopoShape(
         thickness->Faces.getValue(),
         Part::ShapeOption::ResolveLink | Part::ShapeOption::Transform
     );