214 lines
6.4 KiB
C++
214 lines
6.4 KiB
C++
//=======================================================================
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// Copyright (c) Aaron Windsor 2007
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//
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// Distributed under the Boost Software License, Version 1.0. (See
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// accompanying file LICENSE_1_0.txt or copy at
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// http://www.boost.org/LICENSE_1_0.txt)
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//=======================================================================
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#ifndef __PLANAR_FACE_TRAVERSAL_HPP__
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#define __PLANAR_FACE_TRAVERSAL_HPP__
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#include <vector>
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#include <set>
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#include <map>
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#include <boost/next_prior.hpp>
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#include <boost/graph/graph_traits.hpp>
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#include <boost/graph/properties.hpp>
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namespace boost
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{
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struct planar_face_traversal_visitor
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{
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void begin_traversal()
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{}
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void begin_face()
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{}
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template <typename Edge>
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void next_edge(Edge)
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{}
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template <typename Vertex>
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void next_vertex(Vertex)
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{}
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void end_face()
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{}
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void end_traversal()
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{}
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};
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template<typename Graph,
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typename PlanarEmbedding,
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typename Visitor,
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typename EdgeIndexMap>
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void planar_face_traversal(const Graph& g,
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PlanarEmbedding embedding,
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Visitor& visitor, EdgeIndexMap em
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)
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{
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typedef typename graph_traits<Graph>::vertex_descriptor vertex_t;
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typedef typename graph_traits<Graph>::edge_descriptor edge_t;
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typedef typename graph_traits<Graph>::vertex_iterator vertex_iterator_t;
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typedef typename graph_traits<Graph>::edge_iterator edge_iterator_t;
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typedef typename
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property_traits<PlanarEmbedding>::value_type embedding_value_t;
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typedef typename embedding_value_t::const_iterator embedding_iterator_t;
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typedef typename
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std::vector< std::set<vertex_t> > distinguished_edge_storage_t;
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typedef typename
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std::vector< std::map<vertex_t, edge_t> >
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distinguished_edge_to_edge_storage_t;
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typedef typename
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boost::iterator_property_map
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<typename distinguished_edge_storage_t::iterator, EdgeIndexMap>
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distinguished_edge_map_t;
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typedef typename
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boost::iterator_property_map
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<typename distinguished_edge_to_edge_storage_t::iterator, EdgeIndexMap>
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distinguished_edge_to_edge_map_t;
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distinguished_edge_storage_t visited_vector(num_edges(g));
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distinguished_edge_to_edge_storage_t next_edge_vector(num_edges(g));
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distinguished_edge_map_t visited(visited_vector.begin(), em);
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distinguished_edge_to_edge_map_t next_edge(next_edge_vector.begin(), em);
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vertex_iterator_t vi, vi_end;
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typename std::vector<edge_t>::iterator ei, ei_end;
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edge_iterator_t fi, fi_end;
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embedding_iterator_t pi, pi_begin, pi_end;
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visitor.begin_traversal();
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// Initialize the next_edge property map. This map is initialized from the
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// PlanarEmbedding so that get(next_edge, e)[v] is the edge that comes
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// after e in the clockwise embedding around vertex v.
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for(boost::tie(vi,vi_end) = vertices(g); vi != vi_end; ++vi)
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{
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vertex_t v(*vi);
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pi_begin = embedding[v].begin();
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pi_end = embedding[v].end();
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for(pi = pi_begin; pi != pi_end; ++pi)
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{
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edge_t e(*pi);
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std::map<vertex_t, edge_t> m = get(next_edge, e);
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m[v] = boost::next(pi) == pi_end ? *pi_begin : *boost::next(pi);
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put(next_edge, e, m);
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}
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}
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// Take a copy of the edges in the graph here, since we want to accomodate
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// face traversals that add edges to the graph (for triangulation, in
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// particular) and don't want to use invalidated edge iterators.
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// Also, while iterating over all edges in the graph, we single out
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// any self-loops, which need some special treatment in the face traversal.
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std::vector<edge_t> self_loops;
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std::vector<edge_t> edges_cache;
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std::vector<vertex_t> vertices_in_edge;
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for(boost::tie(fi,fi_end) = edges(g); fi != fi_end; ++fi)
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{
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edge_t e(*fi);
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edges_cache.push_back(e);
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if (source(e,g) == target(e,g))
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self_loops.push_back(e);
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}
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// Iterate over all edges in the graph
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ei_end = edges_cache.end();
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for(ei = edges_cache.begin(); ei != ei_end; ++ei)
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{
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edge_t e(*ei);
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vertices_in_edge.clear();
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vertices_in_edge.push_back(source(e,g));
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vertices_in_edge.push_back(target(e,g));
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typename std::vector<vertex_t>::iterator vi, vi_end;
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vi_end = vertices_in_edge.end();
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//Iterate over both vertices in the current edge
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for(vi = vertices_in_edge.begin(); vi != vi_end; ++vi)
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{
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vertex_t v(*vi);
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std::set<vertex_t> e_visited = get(visited, e);
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typename std::set<vertex_t>::iterator e_visited_found
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= e_visited.find(v);
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if (e_visited_found == e_visited.end())
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visitor.begin_face();
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while (e_visited.find(v) == e_visited.end())
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{
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visitor.next_vertex(v);
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visitor.next_edge(e);
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e_visited.insert(v);
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put(visited, e, e_visited);
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v = source(e,g) == v ? target(e,g) : source(e,g);
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e = get(next_edge, e)[v];
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e_visited = get(visited, e);
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}
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if (e_visited_found == e_visited.end())
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visitor.end_face();
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}
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}
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// Iterate over all self-loops, visiting them once separately
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// (they've already been visited once, this visitation is for
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// the "inside" of the self-loop)
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ei_end = self_loops.end();
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for(ei = self_loops.begin(); ei != ei_end; ++ei)
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{
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visitor.begin_face();
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visitor.next_edge(*ei);
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visitor.next_vertex(source(*ei,g));
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visitor.end_face();
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}
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visitor.end_traversal();
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}
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template<typename Graph, typename PlanarEmbedding, typename Visitor>
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inline void planar_face_traversal(const Graph& g,
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PlanarEmbedding embedding,
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Visitor& visitor
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)
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{
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planar_face_traversal(g, embedding, visitor, get(edge_index, g));
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}
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} //namespace boost
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#endif //__PLANAR_FACE_TRAVERSAL_HPP__
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