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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 | { | |
28 | void begin_traversal() | |
29 | {} | |
30 | ||
31 | void begin_face() | |
32 | {} | |
33 | ||
34 | template <typename Edge> | |
35 | void next_edge(Edge) | |
36 | {} | |
37 | ||
38 | template <typename Vertex> | |
39 | void next_vertex(Vertex) | |
40 | {} | |
41 | ||
42 | void end_face() | |
43 | {} | |
44 | ||
45 | void end_traversal() | |
46 | {} | |
47 | ||
48 | }; | |
49 | ||
50 | ||
51 | ||
52 | ||
53 | ||
54 | template<typename Graph, | |
55 | typename PlanarEmbedding, | |
56 | typename Visitor, | |
57 | typename EdgeIndexMap> | |
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> | |
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__ |