mirror of https://github.com/CGAL/cgal
64 lines
2.0 KiB
C++
64 lines
2.0 KiB
C++
#include <CGAL/Simple_cartesian.h>
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#include <CGAL/Polyhedron_3.h>
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#include <CGAL/Polyhedron_items_with_id_3.h>
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#include <boost/graph/breadth_first_search.hpp>
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#include <fstream>
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typedef CGAL::Simple_cartesian<double> Kernel;
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typedef Kernel::Point_3 Point;
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typedef CGAL::Polyhedron_3<Kernel,CGAL::Polyhedron_items_with_id_3> Polyhedron;
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typedef boost::graph_traits<Polyhedron>::vertex_descriptor vertex_descriptor;
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typedef boost::graph_traits<Polyhedron>::vertex_iterator vertex_iterator;
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int main(int argc, char** argv) {
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Polyhedron P;
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std::ifstream in((argc>1)?argv[1]:"cube.off");
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in >> P ;
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// associate indices to the vertices using the "id()" field of the vertex.
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vertex_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)=vertices(P); vb!=ve; ++vb ){
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vertex_descriptor vd = *vb;
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vd->id() = index++;
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}
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// This is the vector where the distance gets written to
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std::vector<int> distance(P.size_of_vertices());
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// Here we start at an arbitrary vertex
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// Any other vertex could be the starting point
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boost::tie(vb,ve)=vertices(P);
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vertex_descriptor vd = *vb;
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std::cout << "We compute distances to " << vd->point() << std::endl;
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// bfs = breadth first search explores the graph
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// Just as the distance_recorder there is a way to record the predecessor of a vertex
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boost::breadth_first_search(P,
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vd,
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visitor(boost::make_bfs_visitor(boost::record_distances(make_iterator_property_map(distance.begin(),
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get(boost::vertex_index, P)),
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boost::on_tree_edge()))));
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// Traverse all vertices and show at what distance they are
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for(boost::tie(vb,ve)=vertices(P); vb!=ve; ++vb ){
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vd = *vb;
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std::cout << vd->point() << " is " << distance[vd->id()] << " hops away" << std::endl;
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}
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return 0;
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}
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