\( \newcommand{\E}{\mathrm{E}} \) \( \newcommand{\A}{\mathrm{A}} \) \( \newcommand{\R}{\mathrm{R}} \) \( \newcommand{\N}{\mathrm{N}} \) \( \newcommand{\Q}{\mathrm{Q}} \) \( \newcommand{\Z}{\mathrm{Z}} \) \( \def\ccSum #1#2#3{ \sum_{#1}^{#2}{#3} } \def\ccProd #1#2#3{ \sum_{#1}^{#2}{#3} }\)

CGAL 4.8 - Triangulated Surface Mesh Shortest Paths

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Surface_mesh_shortest_path/shortest_paths_with_id.cpp
#include <cstdlib>
#include <iostream>
#include <fstream>
#include <iterator>
#include <CGAL/Exact_predicates_inexact_constructions_kernel.h>
#include <CGAL/Random.h>
#include <CGAL/Polyhedron_3.h>
#include <CGAL/Polyhedron_items_with_id_3.h>
#include <CGAL/IO/Polyhedron_iostream.h>
#include <CGAL/Surface_mesh_shortest_path.h>
#include <CGAL/boost/graph/graph_traits_Polyhedron_3.h>
#include <CGAL/boost/graph/iterator.h>
typedef CGAL::Exact_predicates_inexact_constructions_kernel Kernel;
typedef CGAL::Polyhedron_3<Kernel, CGAL::Polyhedron_items_with_id_3> Polyhedron_3;
typedef CGAL::Surface_mesh_shortest_path_traits<Kernel, Polyhedron_3> Traits;
typedef CGAL::Surface_mesh_shortest_path<Traits> Surface_mesh_shortest_path;
typedef boost::graph_traits<Polyhedron_3> Graph_traits;
typedef Graph_traits::vertex_iterator vertex_iterator;
typedef Graph_traits::face_iterator face_iterator;
int main(int argc, char** argv)
{
// read input polyhedron
Polyhedron_3 polyhedron;
std::ifstream input((argc>1)?argv[1]:"data/elephant.off");
input >> polyhedron;
input.close();
// initialize indices of vertices, halfedges and facets
CGAL::set_halfedgeds_items_id(polyhedron);
// pick up a random face
const size_t randSeed = argc > 2 ? std::atoi(argv[2]) : 7915421;
CGAL::Random rand(randSeed);
const int target_face_index = rand.get_int(0, num_faces(polyhedron));
face_iterator face_it = faces(polyhedron).first;
std::advance(face_it,target_face_index);
// ... and define a barycentric coordinate inside the face
Traits::Barycentric_coordinate face_location = {{0.25, 0.5, 0.25}};
// construct a shortest path query object and add a source point
Surface_mesh_shortest_path shortest_paths(polyhedron);
shortest_paths.add_source_point(*face_it, face_location);
// For all vertices in the polyhedron, compute the points of
// the shortest path to the source point and write them
// into a file readable using the CGAL Polyhedron demo
std::ofstream output("shortest_paths_with_id.cgal");
vertex_iterator vit, vit_end;
for ( boost::tie(vit, vit_end) = vertices(polyhedron);
vit != vit_end; ++vit)
{
std::vector<Traits::Point_3> points;
shortest_paths.shortest_path_points_to_source_points(*vit, std::back_inserter(points));
// print the points
output << points.size() << " ";
for (std::size_t i = 0; i < points.size(); ++i)
output << " " << points[i];
output << std::endl;
}
return 0;
}