//======================================================================= | |
// 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__ |