CGAL 6.1 - CGAL and the Boost Graph Library

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BGL_polyhedron_3/kruskal_with_stored_id.cpp
#include <CGAL/Simple_cartesian.h>
#include <CGAL/Polyhedron_3.h>
#include <CGAL/Polyhedron_items_with_id_3.h>
#include <iostream>
#include <list>
#include <CGAL/boost/graph/kruskal_min_spanning_tree.h>
typedef CGAL::Simple_cartesian<double> Kernel;
typedef Kernel::Point_3 Point;
typedef CGAL::Polyhedron_3<Kernel,CGAL::Polyhedron_items_with_id_3> Polyhedron;
typedef boost::graph_traits<Polyhedron>::vertex_descriptor vertex_descriptor;
typedef boost::graph_traits<Polyhedron>::vertex_iterator vertex_iterator;
typedef boost::graph_traits<Polyhedron>::edge_descriptor edge_descriptor;
void
kruskal( const Polyhedron& P)
{
// We use the default edge weight which is the length of the edge
// This property map is defined in graph_traits_Polyhedron_3.h
// This function call requires a vertex_index_map named parameter which
// when omitted defaults to "get(vertex_index,graph)".
// That default works here because the vertex type has an "id()" method
// field which is used by the vertex_index internal property.
std::list<edge_descriptor> mst;
boost::kruskal_minimum_spanning_tree(P,std::back_inserter(mst));
std::cout << "#VRML V2.0 utf8\n"
"Shape {\n"
"appearance Appearance {\n"
"material Material { emissiveColor 1 0 0}}\n"
"geometry\n"
"IndexedLineSet {\n"
"coord Coordinate {\n"
"point [ \n";
vertex_iterator vb, ve;
for(std::tie(vb,ve) = vertices(P); vb!=ve; ++vb){
std::cout << (*vb)->point() << "\n";
}
std::cout << "]\n"
"}\n"
"coordIndex [\n";
for(std::list<edge_descriptor>::iterator it = mst.begin(); it != mst.end(); ++it){
std::cout << source(*it,P)->id()
<< ", " << target(*it,P)->id() << ", -1\n";
}
std::cout << "]\n"
"}#IndexedLineSet\n"
"}# Shape\n";
}
int main() {
Polyhedron P;
Point a(1,0,0);
Point b(0,1,0);
Point c(0,0,1);
Point d(0,0,0);
P.make_tetrahedron(a,b,c,d);
// associate indices to the vertices using the "id()" field of the vertex.
vertex_iterator vb, ve;
int index = 0;
// std::tie assigns the first and second element of the std::pair
// returned by boost::vertices to the variables vit and ve
for(std::tie(vb,ve)=vertices(P); vb!=ve; ++vb ){
vertex_descriptor vd = *vb;
vd->id() = index++;
}
kruskal(P);
return 0;
}
CGAL::Polyhedron_3
Kernel::Point_3
Kernel
CGAL::Simple_cartesian