collapse_edge_euler.hpp

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// Copyright (c) 2012-2019 University of Lyon and CNRS (France).
// All rights reserved.
//
// This file is part of MEPP2; you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as
// published by the Free Software Foundation; either version 3 of
// the License, or (at your option) any later version.
//
// This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
// WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
#pragma once
 
#include <boost/graph/graph_traits.hpp>
#include <CGAL/boost/graph/iterator.h>
#include <CGAL/boost/graph/Euler_operations.h>
 
namespace FEVV {
namespace Operators {
 
template< typename MutableFaceGraph >
void
collapse_edge_keep_source_euler(
    MutableFaceGraph &g,
    typename boost::graph_traits< MutableFaceGraph >::halfedge_descriptor &h)
{
  // use CGAL::Euler function
  std::cout << "Warning: using CGAL::Euler::collapse_edge()"
            << "\n";
  // CGAL's documentation doesn't specify which one of the
  // source and the target vertex is removed.
  // We experimentaly found that the target vertex is removed,
  // so we need to use "opposite()" here to remove the source
  // vertex.
  CGAL::Euler::collapse_edge(edge(opposite(h, g), g), g);
}
 
template< typename MutableFaceGraph >
void
collapse_edge_keep_target_euler(
    MutableFaceGraph &g,
    typename boost::graph_traits< MutableFaceGraph >::halfedge_descriptor &h)
{
  typedef boost::graph_traits< MutableFaceGraph > GraphTraits;
  typedef typename GraphTraits::halfedge_descriptor halfedge_descriptor;
 
  halfedge_descriptor ho = opposite(h, g);
  collapse_edge_keep_source_euler(g, ho);
  // todo
  // calling collapse_edge_keep_source(g, opposite(h, g))
  // doesn't compile. WHY ?
}
 
} // namespace Operators
} // namespace FEVV