void planar_face_traversal(const Graph& g, PlanarEmbedding embedding, Visitor& visitor, EdgeIndexMap em ) { typedef typename graph_traits<Graph>::vertex_descriptor vertex_t; typedef typename graph_traits<Graph>::edge_descriptor edge_t; typedef typename graph_traits<Graph>::vertex_iterator vertex_iterator_t; typedef typename graph_traits<Graph>::edge_iterator edge_iterator_t; typedef typename property_traits<PlanarEmbedding>::value_type embedding_value_t; typedef typename embedding_value_t::const_iterator embedding_iterator_t; typedef typename std::vector< std::set<vertex_t> > distinguished_edge_storage_t; typedef typename std::vector< std::map<vertex_t, edge_t> > distinguished_edge_to_edge_storage_t; typedef typename boost::iterator_property_map <typename distinguished_edge_storage_t::iterator, EdgeIndexMap> distinguished_edge_map_t; typedef typename boost::iterator_property_map <typename distinguished_edge_to_edge_storage_t::iterator, EdgeIndexMap> distinguished_edge_to_edge_map_t; distinguished_edge_storage_t visited_vector(num_edges(g)); distinguished_edge_to_edge_storage_t next_edge_vector(num_edges(g)); distinguished_edge_map_t visited(visited_vector.begin(), em); distinguished_edge_to_edge_map_t next_edge(next_edge_vector.begin(), em); vertex_iterator_t vi, vi_end; typename std::vector<edge_t>::iterator ei, ei_end; edge_iterator_t fi, fi_end; embedding_iterator_t pi, pi_begin, pi_end; visitor.begin_traversal(); // Initialize the next_edge property map. This map is initialized from the // PlanarEmbedding so that get(next_edge, e)[v] is the edge that comes // after e in the clockwise embedding around vertex v. for(boost::tie(vi,vi_end) = vertices(g); vi != vi_end; ++vi) { vertex_t v(*vi); pi_begin = embedding[v].begin(); pi_end = embedding[v].end(); for(pi = pi_begin; pi != pi_end; ++pi) { edge_t e(*pi); std::map<vertex_t, edge_t> m = get(next_edge, e); m[v] = boost::next(pi) == pi_end ? *pi_begin : *boost::next(pi); put(next_edge, e, m); } } // Take a copy of the edges in the graph here, since we want to accomodate // face traversals that add edges to the graph (for triangulation, in // particular) and don't want to use invalidated edge iterators. // Also, while iterating over all edges in the graph, we single out // any self-loops, which need some special treatment in the face traversal. std::vector<edge_t> self_loops; std::vector<edge_t> edges_cache; std::vector<vertex_t> vertices_in_edge; for(boost::tie(fi,fi_end) = edges(g); fi != fi_end; ++fi) { edge_t e(*fi); edges_cache.push_back(e); if (source(e,g) == target(e,g)) self_loops.push_back(e); } // Iterate over all edges in the graph ei_end = edges_cache.end(); for(ei = edges_cache.begin(); ei != ei_end; ++ei) { edge_t e(*ei); vertices_in_edge.clear(); vertices_in_edge.push_back(source(e,g)); vertices_in_edge.push_back(target(e,g)); typename std::vector<vertex_t>::iterator vi, vi_end; vi_end = vertices_in_edge.end(); //Iterate over both vertices in the current edge for(vi = vertices_in_edge.begin(); vi != vi_end; ++vi) { vertex_t v(*vi); std::set<vertex_t> e_visited = get(visited, e); typename std::set<vertex_t>::iterator e_visited_found = e_visited.find(v); if (e_visited_found == e_visited.end()) visitor.begin_face(); while (e_visited.find(v) == e_visited.end()) { visitor.next_vertex(v); visitor.next_edge(e); e_visited.insert(v); put(visited, e, e_visited); v = source(e,g) == v ? target(e,g) : source(e,g); e = get(next_edge, e)[v]; e_visited = get(visited, e); } if (e_visited_found == e_visited.end()) visitor.end_face(); } } // Iterate over all self-loops, visiting them once separately // (they've already been visited once, this visitation is for // the "inside" of the self-loop) ei_end = self_loops.end(); for(ei = self_loops.begin(); ei != ei_end; ++ei) { visitor.begin_face(); visitor.next_edge(*ei); visitor.next_vertex(source(*ei,g)); visitor.end_face(); } visitor.end_traversal(); }