Point operator()( const Vertex& v) const {
std::size_t degree = CGAL::circulator_size( v.vertex_begin());
if ( degree & 1) // odd degree only at border vertices
return v.point();
degree = degree / 2;
double alpha = ( 4.0 - 2.0 * std::cos( 2.0 * CGAL_PI / degree)) / 9.0;
Vector vec = (v.point() - CGAL::ORIGIN) * ( 1.0 - alpha);
HV_circulator h = v.vertex_begin();
do {
// Even degree and border edges indicated non-manifold
// vertex with two holes.
if ( h->is_border_edge()) {
std::cerr << "Error: non-manifold vertex. Erroneous smoothing."
<< std::endl;
return v.point();
}
vec = vec + ( h->opposite()->vertex()->point() - CGAL::ORIGIN)
* alpha / static_cast<double>(degree);
++ h;
CGAL_assertion( h != v.vertex_begin()); // even degree guaranteed
++ h;
} while ( h != v.vertex_begin());
return (CGAL::ORIGIN + vec);
}
