Chris@16: //=======================================================================
Chris@16: // Copyright (c) Aaron Windsor 2007
Chris@16: //
Chris@16: // Distributed under the Boost Software License, Version 1.0. (See
Chris@16: // accompanying file LICENSE_1_0.txt or copy at
Chris@16: // http://www.boost.org/LICENSE_1_0.txt)
Chris@16: //=======================================================================
Chris@16: 
Chris@16: #ifndef __PLANAR_FACE_TRAVERSAL_HPP__
Chris@16: #define __PLANAR_FACE_TRAVERSAL_HPP__
Chris@16: 
Chris@16: #include <vector>
Chris@16: #include <set>
Chris@16: #include <map>
Chris@16: #include <boost/next_prior.hpp>
Chris@16: #include <boost/graph/graph_traits.hpp>
Chris@16: #include <boost/graph/properties.hpp>
Chris@16: 
Chris@16: 
Chris@16: namespace boost
Chris@16: {
Chris@16: 
Chris@16: 
Chris@16: 
Chris@16: 
Chris@16:   struct planar_face_traversal_visitor
Chris@16:   {
Chris@16:     void begin_traversal()
Chris@16:     {}
Chris@16: 
Chris@16:     void begin_face()
Chris@16:     {}
Chris@16: 
Chris@16:     template <typename Edge>
Chris@16:     void next_edge(Edge)
Chris@16:     {}
Chris@16: 
Chris@16:     template <typename Vertex>
Chris@16:     void next_vertex(Vertex)
Chris@16:     {}
Chris@16: 
Chris@16:     void end_face()
Chris@16:     {}
Chris@16: 
Chris@16:     void end_traversal()
Chris@16:     {}
Chris@16: 
Chris@16:   };
Chris@16: 
Chris@16: 
Chris@16: 
Chris@16: 
Chris@16: 
Chris@16:   template<typename Graph, 
Chris@16:            typename PlanarEmbedding, 
Chris@16:            typename Visitor, 
Chris@16:            typename EdgeIndexMap>
Chris@16:   void planar_face_traversal(const Graph& g, 
Chris@16:                              PlanarEmbedding embedding, 
Chris@16:                              Visitor& visitor, EdgeIndexMap em
Chris@16:                              )
Chris@16:   {
Chris@16:     typedef typename graph_traits<Graph>::vertex_descriptor vertex_t;
Chris@16:     typedef typename graph_traits<Graph>::edge_descriptor edge_t;
Chris@16:     typedef typename graph_traits<Graph>::vertex_iterator vertex_iterator_t;
Chris@16:     typedef typename graph_traits<Graph>::edge_iterator edge_iterator_t;
Chris@16:     typedef typename 
Chris@16:       property_traits<PlanarEmbedding>::value_type embedding_value_t;
Chris@16:     typedef typename embedding_value_t::const_iterator embedding_iterator_t;
Chris@16: 
Chris@16:     typedef typename 
Chris@16:       std::vector< std::set<vertex_t> > distinguished_edge_storage_t;
Chris@16:     typedef typename 
Chris@16:       std::vector< std::map<vertex_t, edge_t> > 
Chris@16:       distinguished_edge_to_edge_storage_t;
Chris@16: 
Chris@16:     typedef typename 
Chris@16:       boost::iterator_property_map
Chris@16:         <typename distinguished_edge_storage_t::iterator, EdgeIndexMap>
Chris@16:       distinguished_edge_map_t;
Chris@16: 
Chris@16:     typedef typename 
Chris@16:       boost::iterator_property_map
Chris@16:         <typename distinguished_edge_to_edge_storage_t::iterator, EdgeIndexMap>
Chris@16:       distinguished_edge_to_edge_map_t;
Chris@16: 
Chris@16:     distinguished_edge_storage_t visited_vector(num_edges(g));
Chris@16:     distinguished_edge_to_edge_storage_t next_edge_vector(num_edges(g));
Chris@16: 
Chris@16:     distinguished_edge_map_t visited(visited_vector.begin(), em);
Chris@16:     distinguished_edge_to_edge_map_t next_edge(next_edge_vector.begin(), em);
Chris@16: 
Chris@16:     vertex_iterator_t vi, vi_end;
Chris@16:     typename std::vector<edge_t>::iterator ei, ei_end;
Chris@16:     edge_iterator_t fi, fi_end;
Chris@16:     embedding_iterator_t pi, pi_begin, pi_end;
Chris@16: 
Chris@16:     visitor.begin_traversal();
Chris@16: 
Chris@16:     // Initialize the next_edge property map. This map is initialized from the
Chris@16:     // PlanarEmbedding so that get(next_edge, e)[v] is the edge that comes
Chris@16:     // after e in the clockwise embedding around vertex v.
Chris@16: 
Chris@16:     for(boost::tie(vi,vi_end) = vertices(g); vi != vi_end; ++vi)
Chris@16:       {
Chris@16:         vertex_t v(*vi);
Chris@16:         pi_begin = embedding[v].begin();
Chris@16:         pi_end = embedding[v].end();
Chris@16:         for(pi = pi_begin; pi != pi_end; ++pi)
Chris@16:           {
Chris@16:             edge_t e(*pi);
Chris@16:             std::map<vertex_t, edge_t> m = get(next_edge, e);
Chris@16:             m[v] = boost::next(pi) == pi_end ? *pi_begin : *boost::next(pi);
Chris@16:             put(next_edge, e, m);
Chris@16:           } 
Chris@16:       }
Chris@16: 
Chris@16:     // Take a copy of the edges in the graph here, since we want to accomodate
Chris@16:     // face traversals that add edges to the graph (for triangulation, in 
Chris@16:     // particular) and don't want to use invalidated edge iterators.
Chris@16:     // Also, while iterating over all edges in the graph, we single out
Chris@16:     // any self-loops, which need some special treatment in the face traversal.
Chris@16: 
Chris@16:     std::vector<edge_t> self_loops;
Chris@16:     std::vector<edge_t> edges_cache;
Chris@16:     std::vector<vertex_t> vertices_in_edge;
Chris@16: 
Chris@16:     for(boost::tie(fi,fi_end) = edges(g); fi != fi_end; ++fi)
Chris@16:       {
Chris@16:         edge_t e(*fi);
Chris@16:         edges_cache.push_back(e);
Chris@16:         if (source(e,g) == target(e,g))
Chris@16:           self_loops.push_back(e);
Chris@16:       }
Chris@16: 
Chris@16: 
Chris@16:     // Iterate over all edges in the graph
Chris@16:     ei_end = edges_cache.end();
Chris@16:     for(ei = edges_cache.begin(); ei != ei_end; ++ei)
Chris@16:       {
Chris@16: 
Chris@16:         edge_t e(*ei);
Chris@16:         vertices_in_edge.clear();
Chris@16:         vertices_in_edge.push_back(source(e,g));
Chris@16:         vertices_in_edge.push_back(target(e,g));
Chris@16: 
Chris@16:         typename std::vector<vertex_t>::iterator vi, vi_end;
Chris@16:         vi_end = vertices_in_edge.end();
Chris@16:         
Chris@16:         //Iterate over both vertices in the current edge
Chris@16:         for(vi = vertices_in_edge.begin(); vi != vi_end; ++vi)
Chris@16:           {
Chris@16: 
Chris@16:             vertex_t v(*vi);
Chris@16:             std::set<vertex_t> e_visited = get(visited, e);
Chris@16:             typename std::set<vertex_t>::iterator e_visited_found 
Chris@16:               = e_visited.find(v);
Chris@16:             
Chris@16:             if (e_visited_found == e_visited.end())
Chris@16:               visitor.begin_face();
Chris@16:             
Chris@16:             while (e_visited.find(v) == e_visited.end())
Chris@16:               {
Chris@16:                 visitor.next_vertex(v);
Chris@16:                 visitor.next_edge(e);
Chris@16:                 e_visited.insert(v);
Chris@16:                 put(visited, e, e_visited);
Chris@16:                 v = source(e,g) == v ? target(e,g) : source(e,g);
Chris@16:                 e = get(next_edge, e)[v];
Chris@16:                 e_visited = get(visited, e);
Chris@16:               }
Chris@16:             
Chris@16:             if (e_visited_found == e_visited.end())
Chris@16:               visitor.end_face();
Chris@16:             
Chris@16:           }
Chris@16: 
Chris@16:       }
Chris@16: 
Chris@16:     // Iterate over all self-loops, visiting them once separately
Chris@16:     // (they've already been visited once, this visitation is for
Chris@16:     // the "inside" of the self-loop)
Chris@16:     
Chris@16:     ei_end = self_loops.end();
Chris@16:     for(ei = self_loops.begin(); ei != ei_end; ++ei)
Chris@16:       {
Chris@16:         visitor.begin_face();
Chris@16:         visitor.next_edge(*ei);
Chris@16:         visitor.next_vertex(source(*ei,g));
Chris@16:         visitor.end_face();
Chris@16:       }
Chris@16: 
Chris@16:     visitor.end_traversal();
Chris@16: 
Chris@16:   }
Chris@16: 
Chris@16: 
Chris@16: 
Chris@16:   template<typename Graph, typename PlanarEmbedding, typename Visitor>
Chris@16:   inline void planar_face_traversal(const Graph& g, 
Chris@16:                                     PlanarEmbedding embedding, 
Chris@16:                                     Visitor& visitor
Chris@16:                                     )
Chris@16:   {
Chris@16:     planar_face_traversal(g, embedding, visitor, get(edge_index, g));
Chris@16:   }
Chris@16: 
Chris@16: 
Chris@16: 
Chris@16: 
Chris@16: } //namespace boost
Chris@16: 
Chris@16: #endif //__PLANAR_FACE_TRAVERSAL_HPP__