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How to get the coordinates of the center of mass of a TopoDS_Face?

Will Tran's picture

As well as for TopoDS_Vertex we can get the coordinates with:

int i=0;
exp0.Init(shape, TopAbs_VERTEX);
for(exp0.Init(shape, TopAbs_VERTEX); exp0.More(); exp0.Next()) {
    TopoDS_Vertex vertex = TopoDS::Vertex(exp0.Current());
    gp_Pnt pnt = BRep_Tool::Pnt(vertex);
    cout <<"Edge " << i << ": X: " << pnt.X() << " - Y:" << pnt.Y() << " - Z: " << pnt.Z();

I would like to know if there is a similar mechanism to get the coordinates of a TopoDS_Face.


With the suggestion of @jaba, that's what I did to calculate the center of mass of a series of points:

vtkSmartPointer<vtkPoints> facePoints = vtkSmartPointer<vtkPoints>::New();
int i=0;
for(exp0.Init(shape, TopAbs_FACE); exp0.More(); exp0.Next(), i++, count++) {
    TopoDS_Face aFace = TopoDS::Face(exp0.Current());
    for (TopExp_Explorer Vex(aFace, TopAbs_VERTEX); Vex.More(); Vex.Next()) {
        TopoDS_Vertex vertex = TopoDS::Vertex(Vex.Current());
        gp_Pnt pnt = BRep_Tool::Pnt(vertex);
    vtkSmartPointer<vtkPolyData> polydata = vtkSmartPointer<vtkPolyData>::New();

    // Compute the center of mass
    vtkSmartPointer<vtkCenterOfMass> centerOfMassFilter = vtkSmartPointer<vtkCenterOfMass>::New();
    double center[3];

Kirill Gavrilov's picture

Your code considers only topological vertices on the Face within calculations, while real geometry might be much more complicated.
OCCT provides native tools for computing surface and volume properties.
Take a look at documentation of tool BRepGProp, or Draw Harness commands vprops/sprops/lprops.