CGAL 6.2 - CGAL and the Boost Graph Library: BGL_triangulation_2/dijkstra.cpp

CGAL 6.2 - CGAL and the Boost Graph Library

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BGL_triangulation_2/dijkstra.cpp
#include <CGAL/Exact_predicates_inexact_constructions_kernel.h>
#include <CGAL/boost/graph/graph_traits_Triangulation_2.h>
#include <boost/graph/dijkstra_shortest_paths.hpp>
#include <fstream>
typedef CGAL::Exact_predicates_inexact_constructions_kernel K;
typedef K::Point_2 Point;
typedef CGAL::Triangulation_2<K> Triangulation;
typedef boost::graph_traits<Triangulation>::vertex_descriptor vertex_descriptor;
typedef boost::graph_traits<Triangulation>::vertex_iterator vertex_iterator;
typedef std::map<vertex_descriptor, int> VertexIndexMap;
typedef boost::associative_property_map<VertexIndexMap> VertexIdPropertyMap;
int main(int argc,char* argv[])
{
const char* filename = (argc > 1) ? argv[1] : "data/points.xy";
std::ifstream input(filename);
Triangulation tr;
Point p ;
while(input >> p)
tr.insert(p);
vertex_iterator vit, ve;
// Associate indices to the vertices
VertexIndexMap vertex_id_map;
VertexIdPropertyMap vertex_index_pmap(vertex_id_map);
int index = 0;
for(vertex_descriptor vd : vertices(tr))
vertex_id_map[vd] = index++;
// Dijkstra's shortest path needs property maps for the predecessor and distance
// We first declare a vector
std::vector<vertex_descriptor> predecessor(num_vertices(tr));
// and then turn it into a property map
boost::iterator_property_map<std::vector<vertex_descriptor>::iterator, VertexIdPropertyMap>
predecessor_pmap(predecessor.begin(), vertex_index_pmap);
std::vector<double> distance(num_vertices(tr));
boost::iterator_property_map<std::vector<double>::iterator, VertexIdPropertyMap>
distance_pmap(distance.begin(), vertex_index_pmap);
// start at an arbitrary vertex
vertex_descriptor source = *vertices(tr).first;
std::cout << "\nStart dijkstra_shortest_paths at " << source->point() <<"\n";
boost::dijkstra_shortest_paths(tr, source,
distance_map(distance_pmap)
.predecessor_map(predecessor_pmap)
.vertex_index_map(vertex_index_pmap));
for(vertex_descriptor vd : vertices(tr))
{
std::cout << vd->point() << " [" << vertex_id_map[vd] << "] ";
std::cout << " has distance = " << get(distance_pmap,vd)
<< " and predecessor ";
vd = get(predecessor_pmap,vd);
std::cout << vd->point() << " [" << vertex_id_map[vd] << "]\n ";
}
return EXIT_SUCCESS;
}
CGAL::Exact_predicates_inexact_constructions_kernel
CGAL::Triangulation_2