127 lines
4.3 KiB
C++
127 lines
4.3 KiB
C++
// Copyright (c) 2011 CNRS and LIRIS' Establishments (France).
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// All rights reserved.
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//
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// This file is part of CGAL (www.cgal.org)
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//
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// $URL: https://github.com/CGAL/cgal/blob/v5.1/Triangulation_2/include/CGAL/Triangulation_2_to_lcc.h $
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// $Id: Triangulation_2_to_lcc.h 0779373 2020-03-26T13:31:46+01:00 Sébastien Loriot
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// SPDX-License-Identifier: LGPL-3.0-or-later OR LicenseRef-Commercial
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//
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// Author(s) : Guillaume Damiand <guillaume.damiand@liris.cnrs.fr>
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//
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#ifndef CGAL_TRIANGULATION_2_TO_LCC_H
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#define CGAL_TRIANGULATION_2_TO_LCC_H
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#include <CGAL/assertions.h>
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#include <map>
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namespace CGAL {
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/** Convert a given Triangulation_2 into a 2D linear cell complex.
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* @param alcc the used linear cell complex.
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* @param atr the Triangulation_2.
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* @param aface_to_dart a pointer to a std::map associating to each
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* triangle of atr a corresponding dart in alcc. Not used if nullptr.
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* @return A dart incident to the infinite vertex.
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*/
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template < class LCC, class Triangulation >
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typename LCC::Dart_handle import_from_triangulation_2
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(LCC& alcc, const Triangulation &atr,
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std::map<typename Triangulation::Face_handle,
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typename LCC::Dart_handle >* aface_to_dart=nullptr)
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{
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CGAL_static_assertion( LCC::dimension>=2 && LCC::ambient_dimension==2 );
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// Case of empty triangulations.
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if (atr.number_of_vertices()==0) return LCC::null_handle;
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// Check the dimension.
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if (atr.dimension()!=2) return LCC::null_handle;
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CGAL_assertion(atr.is_valid());
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typedef typename Triangulation::Vertex_handle TVertex_handle;
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typedef typename Triangulation::All_vertices_iterator TVertex_iterator;
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typedef typename Triangulation::All_faces_iterator TFace_iterator;
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typedef typename std::map
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< TFace_iterator, typename LCC::Dart_handle >::iterator itmap_tcell;
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// Create vertices in the map and associate in a map
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// TVertex_handle and vertices in the map.
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std::map< TVertex_handle, typename LCC::Vertex_attribute_handle > TV;
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for (TVertex_iterator itv = atr.all_vertices_begin();
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itv != atr.all_vertices_end(); ++itv)
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{
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TV[itv] = alcc.create_vertex_attribute(itv->point());
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}
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// Create the triangles and create a map to link Cell_iterator
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// and triangles.
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TFace_iterator it;
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std::map<typename Triangulation::Face_handle, typename LCC::Dart_handle> TC;
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std::map<typename Triangulation::Face_handle, typename LCC::Dart_handle>*
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mytc = (aface_to_dart==nullptr?&TC:aface_to_dart);
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itmap_tcell maptcell_it;
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typename LCC::Dart_handle res=LCC::null_handle, dart=LCC::null_handle;
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typename LCC::Dart_handle cur=LCC::null_handle, neighbor=LCC::null_handle;
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for (it = atr.all_faces_begin(); it != atr.all_faces_end(); ++it)
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{
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/* if (it->vertex(0) != atr.infinite_vertex() &&
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it->vertex(1) != atr.infinite_vertex() &&
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it->vertex(2) != atr.infinite_vertex() &&
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it->vertex(3) != atr.infinite_vertex())
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*/
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{
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res = alcc.make_triangle(TV[it->vertex(0)],
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TV[it->vertex(1)],
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TV[it->vertex(2)]);
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if ( dart==LCC::null_handle )
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{
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if ( it->vertex(0) == atr.infinite_vertex() )
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dart = res;
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else if ( it->vertex(1) == atr.infinite_vertex() )
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dart = alcc.next(res);
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else if ( it->vertex(2) == atr.infinite_vertex() )
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dart = alcc.previous(res);
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}
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for (unsigned int i=0; i<3; ++i)
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{
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switch (i)
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{
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case 0: cur = alcc.next(res); break;
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case 1: cur = alcc.previous(res); break;
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case 2: cur = res; break;
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}
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maptcell_it = mytc->find(it->neighbor(i));
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if (maptcell_it != mytc->end())
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{
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switch (atr.mirror_index(it,i) )
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{
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case 0: neighbor = alcc.next(maptcell_it->second);
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break;
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case 1: neighbor = alcc.previous(maptcell_it->second);
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break;
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case 2: neighbor = maptcell_it->second; break;
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}
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alcc.template set_opposite<2>(cur, neighbor);
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}
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}
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(*mytc)[it] = res;
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}
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}
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CGAL_assertion(dart!=LCC::null_handle);
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return dart;
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}
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} // namespace CGAL
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#endif // CGAL_TRIANGULATION_2_TO_LCC_H
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