mirror of https://github.com/CGAL/cgal
93 lines
3.4 KiB
C++
93 lines
3.4 KiB
C++
#include <CGAL/Exact_predicates_inexact_constructions_kernel.h>
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#include <CGAL/Regular_triangulation_2.h>
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#include <CGAL/boost/graph/graph_traits_Regular_triangulation_2.h>
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#include <boost/property_map/function_property_map.hpp>
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#include <boost/graph/kruskal_min_spanning_tree.hpp>
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#include <fstream>
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#include <iostream>
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#include <map>
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typedef CGAL::Exact_predicates_inexact_constructions_kernel K;
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typedef K::FT FT;
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typedef K::Weighted_point_2 Weighted_point;
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typedef CGAL::Regular_triangulation_2<K> Triangulation;
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typedef boost::graph_traits<Triangulation>::vertex_descriptor vertex_descriptor;
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typedef boost::graph_traits<Triangulation>::vertex_iterator vertex_iterator;
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typedef boost::graph_traits<Triangulation>::edge_descriptor edge_descriptor;
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template <typename T>
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struct Compute_edge_weight
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{
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const T& t_;
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Compute_edge_weight(const T& t) : t_(t) { }
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typedef typename boost::graph_traits<T>::vertex_descriptor vertex_descriptor;
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typedef typename boost::graph_traits<T>::edge_descriptor edge_descriptor;
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FT operator()(const edge_descriptor ed) const {
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vertex_descriptor svd = source(ed, t_);
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vertex_descriptor tvd = target(ed, t_);
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typename T::Vertex_handle sv = svd;
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typename T::Vertex_handle tv = tvd;
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return CGAL::power_product(sv->point(), tv->point());
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}
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};
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// The BGL makes use of indices associated to the vertices
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// We use a std::map to store the index
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typedef std::map<vertex_descriptor,int> VertexIndexMap;
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// A std::map is not a property map, because it is not lightweight
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typedef boost::associative_property_map<VertexIndexMap> VertexIdPropertyMap;
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int main(int argc,char* argv[])
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{
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const char* filename = (argc > 1) ? argv[1] : "data/weighted_points.xyw";
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std::ifstream input(filename);
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Triangulation tr;
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Weighted_point wp;
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while(input >> wp)
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tr.insert(wp);
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// Note that with the input "data/weighted_points.xyw", there is one hidden vertex
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std::cout << "number of hidden vertices: " << tr.number_of_hidden_vertices() << std::endl;
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// Associate indices to the vertices
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VertexIndexMap vertex_id_map;
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VertexIdPropertyMap vertex_index_pmap(vertex_id_map);
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int index = 0;
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for(vertex_descriptor vd : vertices(tr))
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vertex_id_map[vd]= index++;
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// We use a custom edge length property map that computes the power distance
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// between the extremities of an edge of the regular triangulation
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typedef Compute_edge_weight<Triangulation> Edge_weight_functor;
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// In the function call you can see a named parameter: vertex_index_map
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std::list<edge_descriptor> mst;
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boost::kruskal_minimum_spanning_tree(tr, std::back_inserter(mst),
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vertex_index_map(vertex_index_pmap)
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.weight_map(boost::make_function_property_map<
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edge_descriptor, FT, Edge_weight_functor>(Edge_weight_functor(tr))));
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std::cout << "The edges of the Euclidean mimimum spanning tree:" << std::endl;
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for(edge_descriptor ed : mst)
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{
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vertex_descriptor svd = source(ed, tr);
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vertex_descriptor tvd = target(ed, tr);
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Triangulation::Vertex_handle sv = svd;
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Triangulation::Vertex_handle tv = tvd;
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std::cout << "[ " << sv->point() << " | " << tv->point() << " ] " << std::endl;
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}
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return EXIT_SUCCESS;
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}
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