Segmentation (like triangulation)

It seem as if the shape had to be triangulated. But i need no tirangulation, only the segmentation (triangulation is really slow, so sometimes wireframe is used instead).

I'v tried Brep_Tool::Polygon3D but it returns null all the time:

BRepPrimAPI_MakeSphere S(gp_Pnt(0,300,0), 100.);
TopoDS_Shape s = S.Shape();

TopExp_Explorer ex;
for( ex.Init(s, TopAbs_EDGE); ex.More(); ex.Next() )
{
const Handle_Poly_Polygon3D& seg = BRep_Tool::
Polygon3D(TopoDS_Edge(ex.Current()), l);

if(seg.IsNull()) {
//always
}
....
}

Is there a similar function like BRepMesh::Mesh(...) for the edges???