extend interface to get actual property with geometric data, get center of gravity of a geometry

src/App/ComplexGeoData.cpp

@@ -148,3 +148,8 @@ void ComplexGeoData::getFaces(std::vector<Base::Vector3d> &Points,
     (void)Accuracy;
     (void)flags;
 }
+
+bool ComplexGeoData::getCenterOfGravity(Base::Vector3d&) const
+{
+    return false;
+}

src/App/ComplexGeoData.h

@@ -145,6 +145,11 @@ public:
     /** Get faces from object with given accuracy */
     virtual void getFaces(std::vector<Base::Vector3d> &Points,std::vector<Facet> &faces,
         float Accuracy, uint16_t flags=0) const;
+    /** Get the center of gravity
+     * If this method is implemented then true is returned and the center of gravity.
+     * The default implementation only returns false.
+     */
+    virtual bool getCenterOfGravity(Base::Vector3d& center) const;
     //@}
 
 protected:

src/App/GeoFeature.cpp

@@ -53,3 +53,8 @@ void GeoFeature::transformPlacement(const Base::Placement &transform)
     plm = transform * plm;
     this->Placement.setValue(plm);
 }
+
+const PropertyComplexGeoData* GeoFeature::getPropertyOfGeometry() const
+{
+    return nullptr;
+}

src/App/GeoFeature.h

@@ -54,6 +54,13 @@ public:
      * @param transform (input).
      */
     virtual void transformPlacement(const Base::Placement &transform);
+    /**
+     * This method returns the main property of a geometric object that holds
+     * the actual geometry. For a part object this is the Shape property, for
+     * a mesh object the Mesh property and so on.
+     * The default implementation returns null.
+     */
+    virtual const PropertyComplexGeoData* getPropertyOfGeometry() const;
 };
 
 } //namespace App

src/Mod/Mesh/App/MeshFeature.h

@@ -77,6 +77,9 @@ public:
     virtual const char* getViewProviderName(void) const {
         return "MeshGui::ViewProviderMeshFaceSet";
     }
+    virtual const App::PropertyComplexGeoData* getPropertyOfGeometry() const {
+        return &Mesh;
+    }
 
     /// handles the MeshPy object
     virtual PyObject* getPyObject(void);

src/Mod/Part/App/PartFeature.cpp

@@ -238,6 +238,11 @@ const char* Feature::getViewProviderName(void) const {
     return "PartGui::ViewProviderPart";
 }
 
+const App::PropertyComplexGeoData* Feature::getPropertyOfGeometry() const
+{
+    return &Shape;
+}
+
 // ---------------------------------------------------------
 
 PROPERTY_SOURCE(Part::FilletBase, Part::Feature)

src/Mod/Part/App/PartFeature.h

@@ -60,6 +60,7 @@ public:
 
     /// returns the type name of the ViewProvider
     virtual const char* getViewProviderName(void) const;
+    virtual const App::PropertyComplexGeoData* getPropertyOfGeometry() const;
 
     virtual PyObject* getPyObject(void);
     virtual std::vector<PyObject *> getPySubObjects(const std::vector<std::string>&) const;

src/Mod/Part/App/TopoShape.cpp

@@ -63,6 +63,7 @@
 # include <BRepCheck_Result.hxx>
 # include <BRepClass_FaceClassifier.hxx>
 # include <BRepFilletAPI_MakeFillet.hxx>
+# include <BRepGProp.hxx>
 # include <BRepMesh_IncrementalMesh.hxx>
 # include <BRepMesh_Triangle.hxx>
 # include <BRepMesh_Edge.hxx>
@@ -94,6 +95,7 @@
 # include <GeomFill_SectionLaw.hxx>
 # include <GeomFill_Sweep.hxx>
 # include <GeomLib.hxx>
+# include <GProp_GProps.hxx>
 # include <Law_BSpFunc.hxx>
 # include <Law_BSpline.hxx>
 # include <Law_BSpFunc.hxx>
@@ -928,6 +930,36 @@ Base::BoundBox3d TopoShape::getBoundBox(void) const
     return box;
 }
 
+bool TopoShape::getCenterOfGravity(Base::Vector3d& center) const
+{
+    if (_Shape.IsNull())
+        return false;
+
+    // Computing of CentreOfMass
+    gp_Pnt pnt;
+
+    if (_Shape.ShapeType() == TopAbs_VERTEX) {
+        pnt = BRep_Tool::Pnt(TopoDS::Vertex(_Shape));
+    }
+    else {
+        GProp_GProps prop;
+        if (_Shape.ShapeType() == TopAbs_EDGE || _Shape.ShapeType() == TopAbs_WIRE) {
+            BRepGProp::LinearProperties(_Shape, prop);
+        }
+        else if (_Shape.ShapeType() == TopAbs_FACE || _Shape.ShapeType() == TopAbs_SHELL) {
+            BRepGProp::SurfaceProperties(_Shape, prop);
+        }
+        else {
+            BRepGProp::VolumeProperties(_Shape, prop);
+        }
+
+        pnt = prop.CentreOfMass();
+    }
+
+    center.Set(pnt.X(), pnt.Y(), pnt.Z());
+    return true;
+}
+
 void TopoShape::Save (Base::Writer & ) const
 {
 }

src/Mod/Part/App/TopoShape.h

@@ -81,6 +81,7 @@ public:
     Base::Matrix4D getTransform(void) const;
     /// Bound box from the CasCade shape
     Base::BoundBox3d getBoundBox(void)const;
+    virtual bool getCenterOfGravity(Base::Vector3d& center) const;
     static void convertTogpTrsf(const Base::Matrix4D& mtrx, gp_Trsf& trsf);
     static void convertToMatrix(const gp_Trsf& trsf, Base::Matrix4D& mtrx);
     //@}

src/Mod/Points/App/PointsFeature.h

@@ -69,6 +69,10 @@ public:
     virtual const char* getViewProviderName(void) const {
         return "PointsGui::ViewProviderScattered";
     }
+
+    virtual const App::PropertyComplexGeoData* getPropertyOfGeometry() const {
+        return &Points;
+    }
 protected:
     void onChanged(const App::Property* prop);
     //@}