| //======================================================================= |
| // Copyright (c) Aaron Windsor 2007 |
| // |
| // Distributed under the Boost Software License, Version 1.0. (See |
| // accompanying file LICENSE_1_0.txt or copy at |
| // http://www.boost.org/LICENSE_1_0.txt) |
| //======================================================================= |
| |
| #ifndef __PLANAR_FACE_TRAVERSAL_HPP__ |
| #define __PLANAR_FACE_TRAVERSAL_HPP__ |
| |
| #include <vector> |
| #include <boost/utility.hpp> //for next and prior |
| #include <boost/graph/graph_traits.hpp> |
| |
| |
| namespace boost |
| { |
| |
| |
| |
| |
| struct planar_face_traversal_visitor |
| { |
| void begin_traversal() |
| {} |
| |
| void begin_face() |
| {} |
| |
| template <typename Edge> |
| void next_edge(Edge) |
| {} |
| |
| template <typename Vertex> |
| void next_vertex(Vertex) |
| {} |
| |
| void end_face() |
| {} |
| |
| void end_traversal() |
| {} |
| |
| }; |
| |
| |
| |
| |
| |
| template<typename Graph, |
| typename PlanarEmbedding, |
| typename Visitor, |
| typename EdgeIndexMap> |
| 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(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(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(); |
| |
| } |
| |
| |
| |
| template<typename Graph, typename PlanarEmbedding, typename Visitor> |
| inline void planar_face_traversal(const Graph& g, |
| PlanarEmbedding embedding, |
| Visitor& visitor |
| ) |
| { |
| planar_face_traversal(g, embedding, visitor, get(edge_index, g)); |
| } |
| |
| |
| |
| |
| } //namespace boost |
| |
| #endif //__PLANAR_FACE_TRAVERSAL_HPP__ |