mirror of https://github.com/CGAL/cgal
111 lines
3.2 KiB
C++
111 lines
3.2 KiB
C++
#include <CGAL/Cartesian.h>
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#include <CGAL/Polyhedron_3.h>
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#include <CGAL/IO/Polyhedron_iostream.h>
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#include <CGAL/boost/graph/graph_traits_Polyhedron_3.h>
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#include <CGAL/boost/graph/properties_Polyhedron_3.h>
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#include <CGAL/Unique_hash_map.h>
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#include <iostream>
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#include <algorithm>
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#include <list>
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#include <boost/graph/kruskal_min_spanning_tree.hpp>
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typedef CGAL::Cartesian<double> Kernel;
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typedef Kernel::Vector_3 Vector;
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typedef Kernel::Point_3 Point;
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typedef CGAL::Polyhedron_3<Kernel> Polyhedron;
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typedef boost::graph_traits<Polyhedron const>::vertex_descriptor vertex_const_descriptor;
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typedef boost::graph_traits<Polyhedron const>::vertex_iterator vertex_const_iterator;
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typedef boost::graph_traits<Polyhedron const>::edge_descriptor edge_const_descriptor;
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// The BGL makes heavy use of indices associated to the vertices
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// We use a std::map to store the index
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namespace CGAL
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{
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// (but we define operator < for handles as is not predefined)
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bool operator< ( vertex_const_descriptor const& x, vertex_const_descriptor const& y )
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{
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return &*x < &*y ;
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}
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}
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typedef std::map<vertex_const_descriptor,int> VertexIndexMap;
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VertexIndexMap vertex_id_map;
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// A std::map is not a property map, because it is not lightweight
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typedef boost::const_associative_property_map<VertexIndexMap> VertexIdPropertyMap;
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VertexIdPropertyMap vertex_index_pmap(vertex_id_map);
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void
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kruskal(const Polyhedron& P)
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{
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// associate indices to the vertices
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{
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vertex_const_iterator vb, ve;
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int index = 0;
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// boost::tie assigns the first and second element of the std::pair
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// returned by boost::vertices to the variables vit and ve
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for(boost::tie(vb,ve)=boost::vertices(P); vb!=ve; ++vb ){
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vertex_const_descriptor vd = *vb;
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vertex_id_map[vd]= index++;
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}
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}
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// We use the default edge weight which is the squared length of the edge
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// This property map is defined in graph_traits_Polyhedron_3.h
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// In the function call you can see a named parameter: vertex_index_map
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std::list<edge_const_descriptor> mst;
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boost::kruskal_minimum_spanning_tree(P,
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std::back_inserter(mst),
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vertex_index_map(vertex_index_pmap));
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vertex_const_iterator vb, ve;
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std::cout << "#VRML V2.0 utf8\n"
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"Shape {\n"
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"appearance Appearance {\n"
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"material Material { emissiveColor 1 0 0}}\n"
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"geometry\n"
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"IndexedLineSet {\n"
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"coord Coordinate {\n"
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"point [ \n";
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for(boost::tie(vb,ve) = boost::vertices(P); vb!=ve; ++vb){
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std::cout << (*vb)->point() << "\n";
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}
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std::cout << "]\n"
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"}\n"
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"coordIndex [\n";
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for(std::list<edge_const_descriptor>::iterator it = mst.begin(); it != mst.end(); ++it)
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{
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edge_const_descriptor e = *it ;
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vertex_const_descriptor s = boost::source(e,P);
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vertex_const_descriptor t = boost::target(e,P);
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std::cout << vertex_id_map[s] << ", " << vertex_id_map[t] << ", -1\n";
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}
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std::cout << "]\n"
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"}#IndexedLineSet\n"
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"}# Shape\n";
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}
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int main() {
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Polyhedron P;
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std::cin >> P;
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kruskal(P);
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return 0;
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}
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