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#include <CGAL/Simple_cartesian.h>
#include <CGAL/boost/graph/graph_traits_Linear_cell_complex_for_combinatorial_map.h>
#include <CGAL/boost/graph/properties_Linear_cell_complex_for_combinatorial_map.h>
#include <CGAL/boost/graph/split_graph_into_polylines.h>
#include <CGAL/IO/polygon_mesh_io.h>
#include <CGAL/extract_mean_curvature_flow_skeleton.h>
#include <fstream>
typedef CGAL::Simple_cartesian<double> Kernel;
typedef Kernel::Point_3 Point;
typedef CGAL::Linear_cell_complex_traits<3, Kernel> MyTraits;
typedef CGAL::Linear_cell_complex_for_bgl_combinatorial_map_helper
<2, 3, MyTraits>::type LCC;
typedef boost::graph_traits<LCC>::vertex_descriptor vertex_descriptor;
typedef CGAL::Mean_curvature_flow_skeletonization<LCC> Skeletonization;
typedef Skeletonization::Skeleton Skeleton;
typedef Skeleton::vertex_descriptor Skeleton_vertex;
typedef Skeleton::edge_descriptor Skeleton_edge;
//only needed for the display of the skeleton as maximal polylines
struct Display_polylines{
const Skeleton& skeleton;
std::ofstream& out;
int polyline_size;
std::stringstream sstr;
Display_polylines(const Skeleton& skeleton, std::ofstream& out)
: skeleton(skeleton), out(out)
{}
void start_new_polyline(){
polyline_size=0;
sstr.str("");
sstr.clear();
}
void add_node(Skeleton_vertex v){
++polyline_size;
sstr << " " << skeleton[v].point;
}
void end_polyline()
{
out << polyline_size << sstr.str() << "\n";
}
};
// This example extracts a medially centered skeleton from a given mesh.
int main()
{
LCC lcc;
CGAL::IO::read_polygon_mesh(CGAL::data_file_path("meshes/elephant.off"), lcc);
Skeleton skeleton;
CGAL::extract_mean_curvature_flow_skeleton(lcc, skeleton);
std::cout << "Number of vertices of the skeleton: " << boost::num_vertices(skeleton) << "\n";
std::cout << "Number of edges of the skeleton: " << boost::num_edges(skeleton) << "\n";
// Output all the edges of the skeleton.
std::ofstream output("skel-lcc.polylines.txt");
Display_polylines display(skeleton,output);
CGAL::split_graph_into_polylines(skeleton, display);
output.close();
// Output skeleton points and the corresponding surface points
output.open("correspondance-lcc.polylines.txt");
for(Skeleton_vertex v : CGAL::make_range(vertices(skeleton)))
for(vertex_descriptor vd : skeleton[v].vertices)
output << "2 " << skeleton[v].point << " "
<< get(CGAL::vertex_point, lcc, vd) << "\n";
return 0;
}
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