1 //======================================================================= 2 // Copyright (c) Aaron Windsor 2007 3 // 4 // Distributed under the Boost Software License, Version 1.0. (See 5 // accompanying file LICENSE_1_0.txt or copy at 6 // http://www.boost.org/LICENSE_1_0.txt) 7 //======================================================================= 8 9 #ifndef __PLANAR_FACE_TRAVERSAL_HPP__ 10 #define __PLANAR_FACE_TRAVERSAL_HPP__ 11 12 #include <vector> 13 #include <set> 14 #include <map> 15 #include <boost/next_prior.hpp> 16 #include <boost/graph/graph_traits.hpp> 17 #include <boost/graph/properties.hpp> 18 19 20 namespace boost 21 { 22 23 24 25 26 struct planar_face_traversal_visitor 27 { begin_traversalboost::planar_face_traversal_visitor28 void begin_traversal() 29 {} 30 begin_faceboost::planar_face_traversal_visitor31 void begin_face() 32 {} 33 34 template <typename Edge> next_edgeboost::planar_face_traversal_visitor35 void next_edge(Edge) 36 {} 37 38 template <typename Vertex> next_vertexboost::planar_face_traversal_visitor39 void next_vertex(Vertex) 40 {} 41 end_faceboost::planar_face_traversal_visitor42 void end_face() 43 {} 44 end_traversalboost::planar_face_traversal_visitor45 void end_traversal() 46 {} 47 48 }; 49 50 51 52 53 54 template<typename Graph, 55 typename PlanarEmbedding, 56 typename Visitor, 57 typename EdgeIndexMap> planar_face_traversal(const Graph & g,PlanarEmbedding embedding,Visitor & visitor,EdgeIndexMap em)58 void planar_face_traversal(const Graph& g, 59 PlanarEmbedding embedding, 60 Visitor& visitor, EdgeIndexMap em 61 ) 62 { 63 typedef typename graph_traits<Graph>::vertex_descriptor vertex_t; 64 typedef typename graph_traits<Graph>::edge_descriptor edge_t; 65 typedef typename graph_traits<Graph>::vertex_iterator vertex_iterator_t; 66 typedef typename graph_traits<Graph>::edge_iterator edge_iterator_t; 67 typedef typename 68 property_traits<PlanarEmbedding>::value_type embedding_value_t; 69 typedef typename embedding_value_t::const_iterator embedding_iterator_t; 70 71 typedef typename 72 std::vector< std::set<vertex_t> > distinguished_edge_storage_t; 73 typedef typename 74 std::vector< std::map<vertex_t, edge_t> > 75 distinguished_edge_to_edge_storage_t; 76 77 typedef typename 78 boost::iterator_property_map 79 <typename distinguished_edge_storage_t::iterator, EdgeIndexMap> 80 distinguished_edge_map_t; 81 82 typedef typename 83 boost::iterator_property_map 84 <typename distinguished_edge_to_edge_storage_t::iterator, EdgeIndexMap> 85 distinguished_edge_to_edge_map_t; 86 87 distinguished_edge_storage_t visited_vector(num_edges(g)); 88 distinguished_edge_to_edge_storage_t next_edge_vector(num_edges(g)); 89 90 distinguished_edge_map_t visited(visited_vector.begin(), em); 91 distinguished_edge_to_edge_map_t next_edge(next_edge_vector.begin(), em); 92 93 vertex_iterator_t vi, vi_end; 94 typename std::vector<edge_t>::iterator ei, ei_end; 95 edge_iterator_t fi, fi_end; 96 embedding_iterator_t pi, pi_begin, pi_end; 97 98 visitor.begin_traversal(); 99 100 // Initialize the next_edge property map. This map is initialized from the 101 // PlanarEmbedding so that get(next_edge, e)[v] is the edge that comes 102 // after e in the clockwise embedding around vertex v. 103 104 for(boost::tie(vi,vi_end) = vertices(g); vi != vi_end; ++vi) 105 { 106 vertex_t v(*vi); 107 pi_begin = embedding[v].begin(); 108 pi_end = embedding[v].end(); 109 for(pi = pi_begin; pi != pi_end; ++pi) 110 { 111 edge_t e(*pi); 112 std::map<vertex_t, edge_t> m = get(next_edge, e); 113 m[v] = boost::next(pi) == pi_end ? *pi_begin : *boost::next(pi); 114 put(next_edge, e, m); 115 } 116 } 117 118 // Take a copy of the edges in the graph here, since we want to accomodate 119 // face traversals that add edges to the graph (for triangulation, in 120 // particular) and don't want to use invalidated edge iterators. 121 // Also, while iterating over all edges in the graph, we single out 122 // any self-loops, which need some special treatment in the face traversal. 123 124 std::vector<edge_t> self_loops; 125 std::vector<edge_t> edges_cache; 126 std::vector<vertex_t> vertices_in_edge; 127 128 for(boost::tie(fi,fi_end) = edges(g); fi != fi_end; ++fi) 129 { 130 edge_t e(*fi); 131 edges_cache.push_back(e); 132 if (source(e,g) == target(e,g)) 133 self_loops.push_back(e); 134 } 135 136 137 // Iterate over all edges in the graph 138 ei_end = edges_cache.end(); 139 for(ei = edges_cache.begin(); ei != ei_end; ++ei) 140 { 141 142 edge_t e(*ei); 143 vertices_in_edge.clear(); 144 vertices_in_edge.push_back(source(e,g)); 145 vertices_in_edge.push_back(target(e,g)); 146 147 typename std::vector<vertex_t>::iterator vi, vi_end; 148 vi_end = vertices_in_edge.end(); 149 150 //Iterate over both vertices in the current edge 151 for(vi = vertices_in_edge.begin(); vi != vi_end; ++vi) 152 { 153 154 vertex_t v(*vi); 155 std::set<vertex_t> e_visited = get(visited, e); 156 typename std::set<vertex_t>::iterator e_visited_found 157 = e_visited.find(v); 158 159 if (e_visited_found == e_visited.end()) 160 visitor.begin_face(); 161 162 while (e_visited.find(v) == e_visited.end()) 163 { 164 visitor.next_vertex(v); 165 visitor.next_edge(e); 166 e_visited.insert(v); 167 put(visited, e, e_visited); 168 v = source(e,g) == v ? target(e,g) : source(e,g); 169 e = get(next_edge, e)[v]; 170 e_visited = get(visited, e); 171 } 172 173 if (e_visited_found == e_visited.end()) 174 visitor.end_face(); 175 176 } 177 178 } 179 180 // Iterate over all self-loops, visiting them once separately 181 // (they've already been visited once, this visitation is for 182 // the "inside" of the self-loop) 183 184 ei_end = self_loops.end(); 185 for(ei = self_loops.begin(); ei != ei_end; ++ei) 186 { 187 visitor.begin_face(); 188 visitor.next_edge(*ei); 189 visitor.next_vertex(source(*ei,g)); 190 visitor.end_face(); 191 } 192 193 visitor.end_traversal(); 194 195 } 196 197 198 199 template<typename Graph, typename PlanarEmbedding, typename Visitor> planar_face_traversal(const Graph & g,PlanarEmbedding embedding,Visitor & visitor)200 inline void planar_face_traversal(const Graph& g, 201 PlanarEmbedding embedding, 202 Visitor& visitor 203 ) 204 { 205 planar_face_traversal(g, embedding, visitor, get(edge_index, g)); 206 } 207 208 209 210 211 } //namespace boost 212 213 #endif //__PLANAR_FACE_TRAVERSAL_HPP__ 214