void modify_vertex_position() { Polyhedron P; Halfedge_handle h = P.make_tetrahedron(); if ( P.is_tetrahedron(h)) { int i(0); for(Vertex_iterator vi = P.vertices_begin(); vi != P.vertices_end(); ++vi,++i) { std::cout << "before changing vertex " << i << ": " << vi->point().x() << vi->point().y() << vi->point().z() << endl; Point_3 pt(1, 0, 0); vi->point() = pt; std::cout << "after changing vertex " << i << ": " << vi->point().x() << vi->point().y() << vi->point().z() << endl; } } }