//======================================================================= // Copyright 2007 Aaron Windsor // // 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) //======================================================================= #include #include #include #include #include #include #include #include #include #include #include // This example shows how to start with a connected planar graph // and add edges to make the graph maximal planar (triangulated.) // Any maximal planar simple graph on n vertices has 3n - 6 edges and // 2n - 4 faces, a consequence of Euler's formula. using namespace boost; // This visitor is passed to planar_face_traversal to count the // number of faces. struct face_counter : public planar_face_traversal_visitor { face_counter() : count(0) {} void begin_face() { ++count; } int count; }; int main(int argc, char** argv) { typedef adjacency_list< vecS, vecS, undirectedS, property< vertex_index_t, int >, property< edge_index_t, int > > graph; // Create the graph - a straight line graph g(10); add_edge(0, 1, g); add_edge(1, 2, g); add_edge(2, 3, g); add_edge(3, 4, g); add_edge(4, 5, g); add_edge(5, 6, g); add_edge(6, 7, g); add_edge(7, 8, g); add_edge(8, 9, g); std::cout << "Since the input graph is planar with " << num_vertices(g) << " vertices," << std::endl << "The output graph should be planar with " << 3 * num_vertices(g) - 6 << " edges and " << 2 * num_vertices(g) - 4 << " faces." << std::endl; // Initialize the interior edge index property_map< graph, edge_index_t >::type e_index = get(edge_index, g); graph_traits< graph >::edges_size_type edge_count = 0; graph_traits< graph >::edge_iterator ei, ei_end; for (boost::tie(ei, ei_end) = edges(g); ei != ei_end; ++ei) put(e_index, *ei, edge_count++); // Test for planarity; compute the planar embedding as a side-effect typedef std::vector< graph_traits< graph >::edge_descriptor > vec_t; std::vector< vec_t > embedding(num_vertices(g)); if (boyer_myrvold_planarity_test(boyer_myrvold_params::graph = g, boyer_myrvold_params::embedding = &embedding[0])) std::cout << "Input graph is planar" << std::endl; else std::cout << "Input graph is not planar" << std::endl; make_biconnected_planar(g, &embedding[0]); // Re-initialize the edge index, since we just added a few edges edge_count = 0; for (boost::tie(ei, ei_end) = edges(g); ei != ei_end; ++ei) put(e_index, *ei, edge_count++); // Test for planarity again; compute the planar embedding as a side-effect if (boyer_myrvold_planarity_test(boyer_myrvold_params::graph = g, boyer_myrvold_params::embedding = &embedding[0])) std::cout << "After calling make_biconnected, the graph is still planar" << std::endl; else std::cout << "After calling make_biconnected, the graph is not planar" << std::endl; make_maximal_planar(g, &embedding[0]); // Re-initialize the edge index, since we just added a few edges edge_count = 0; for (boost::tie(ei, ei_end) = edges(g); ei != ei_end; ++ei) put(e_index, *ei, edge_count++); // Test for planarity one final time; compute the planar embedding as a // side-effect std::cout << "After calling make_maximal_planar, the final graph "; if (boyer_myrvold_planarity_test(boyer_myrvold_params::graph = g, boyer_myrvold_params::embedding = &embedding[0])) std::cout << "is planar." << std::endl; else std::cout << "is not planar." << std::endl; std::cout << "The final graph has " << num_edges(g) << " edges." << std::endl; face_counter count_visitor; planar_face_traversal(g, &embedding[0], count_visitor); std::cout << "The final graph has " << count_visitor.count << " faces." << std::endl; return 0; }