84 lines
2.8 KiB
C++
84 lines
2.8 KiB
C++
// Copyright (c) 1997
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// Utrecht University (The Netherlands),
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// ETH Zurich (Switzerland),
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// INRIA Sophia-Antipolis (France),
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// Max-Planck-Institute Saarbruecken (Germany),
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// and Tel-Aviv University (Israel). 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/HalfedgeDS/include/CGAL/halfedgeds_connected_components.h $
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// $Id: halfedgeds_connected_components.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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//
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// Author(s) : Lutz Kettner <kettner@mpi-sb.mpg.de>
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#ifndef CGAL_HALFEDGEDS_CONNECTED_COMPONENTS_H
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#define CGAL_HALFEDGEDS_CONNECTED_COMPONENTS_H 1
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#include <CGAL/Unique_hash_map.h>
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#include <CGAL/iterator.h>
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#include <vector>
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namespace CGAL {
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template <class HDS, class Output_iterator,
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class Halfedge_iterator, class Halfedge_handle>
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std::size_t
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halfedgeds_connected_components( HDS hds, Output_iterator result) {
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Unique_hash_map< Halfedge_iterator, bool> hedge_map( false);
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std::size_t count = 0;
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std::vector< Halfedge_handle> hstack;
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hstack.reserve( hds.size_of_halfedges() + 3/ 4);
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Halfedge_iterator scan = hds.halfedges_begin();
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while ( scan != hds.halfedges_end()) {
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// first trace the component, then report it
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hstack.clear();
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hstack.push_back( scan);
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while ( ! hstack.empty()) {
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Halfedge_handle h = hstack.back();
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hstack.pop_back();
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if ( ! hedge_map[ h] ) {
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hedge_map[ h] = true;
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hstack.push_back( h->next());
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hstack.push_back( h->opposite());
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}
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}
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++count;
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*result++ = scan;
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while( hedge_map[ scan])
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++scan;
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}
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return count;
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}
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template <class HDS, class Output_iterator>
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std::size_t
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halfedgeds_connected_components( HDS& hds, Output_iterator result) {
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typedef typename HDS::Halfedge_iterator Halfedge_iterator;
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typedef typename HDS::Halfedge_handle Halfedge_handle;
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return halfedgeds_connected_components<HDS&, Output_iterator,
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Halfedge_iterator, Halfedge_handle>( hds, result);
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}
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template <class HDS, class Output_iterator>
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std::size_t
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halfedgeds_connected_components( const HDS& hds, Output_iterator result) {
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typedef typename HDS::Halfedge_const_iterator Halfedge_iterator;
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typedef typename HDS::Halfedge_const_handle Halfedge_handle;
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return halfedgeds_connected_components<const HDS&, Output_iterator,
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Halfedge_iterator, Halfedge_handle>( hds, result);
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}
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template <class HDS>
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std::size_t
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halfedgeds_connected_components( HDS& hds) {
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return halfedgeds_connected_components( hds, Emptyset_iterator());
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}
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} //namespace CGAL
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#endif // CGAL_HALFEDGEDS_CONNECTED_COMPONENTS_H //
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// EOF //
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