_pv[ nbNodes-1 ].SetNodeAndNext( nodes[ nbNodes-1 ], _pv[0], nbNodes-1 );
// assure correctness of PolyVertex::_index as a node can encounter more than once
_pv[ nbNodes-1 ].SetNodeAndNext( nodes[ nbNodes-1 ], _pv[0], nbNodes-1 );
// assure correctness of PolyVertex::_index as a node can encounter more than once