CGAL 6.2 - Triangulated Surface Mesh Shortest Paths

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Surface_mesh_shortest_path/shortest_path_sequence.cpp
#include <CGAL/Exact_predicates_inexact_constructions_kernel.h>
#include <CGAL/Random.h>
#include <CGAL/Surface_mesh.h>
#include <CGAL/Surface_mesh_shortest_path.h>
#include <variant>
#include <boost/lexical_cast.hpp>
#include <cstdlib>
#include <iostream>
#include <fstream>
typedef CGAL::Exact_predicates_inexact_constructions_kernel Kernel;
typedef CGAL::Surface_mesh<Kernel::Point_3> Triangle_mesh;
typedef CGAL::Surface_mesh_shortest_path_traits<Kernel, Triangle_mesh> Traits;
typedef CGAL::Surface_mesh_shortest_path<Traits> Surface_mesh_shortest_path;
typedef Traits::Barycentric_coordinates Barycentric_coordinates;
typedef boost::graph_traits<Triangle_mesh> Graph_traits;
typedef Graph_traits::vertex_iterator vertex_iterator;
typedef Graph_traits::face_iterator face_iterator;
typedef Graph_traits::vertex_descriptor vertex_descriptor;
typedef Graph_traits::face_descriptor face_descriptor;
typedef Graph_traits::halfedge_descriptor halfedge_descriptor;
// A model of SurfacemeshShortestPathVisitor storing simplicies
// using std::variant
struct Sequence_collector
{
typedef std::variant< vertex_descriptor,
std::pair<halfedge_descriptor,double>,
std::pair<face_descriptor, Barycentric_coordinates> > Simplex;
std::vector< Simplex > sequence;
void operator()(halfedge_descriptor he, double alpha)
{
sequence.push_back(std::make_pair(he, alpha));
}
void operator()(vertex_descriptor v)
{
sequence.push_back(v);
}
void operator()(face_descriptor f, Barycentric_coordinates alpha)
{
sequence.push_back(std::make_pair(f, alpha));
}
};
// A visitor to print what a variant contains using std::visit
struct Print_visitor
{
int i;
Triangle_mesh& g;
Print_visitor(Triangle_mesh& g) :i(-1), g(g) {}
void operator()(vertex_descriptor v)
{
std::cout << "#" << ++i << " Vertex: " << get(boost::vertex_index, g)[v];
std::cout << " Position: " << Surface_mesh_shortest_path::point(v, g) << "\n";
}
void operator()(const std::pair<halfedge_descriptor,double>& h_a)
{
std::cout << "#" << ++i << " Edge: " << get(CGAL::halfedge_index, g)[h_a.first] << " , ("
<< 1.0 - h_a.second << " , "
<< h_a.second << ")";
std::cout << " Position: " << Surface_mesh_shortest_path::point(h_a.first, h_a.second, g) << "\n";
}
void operator()(const std::pair<face_descriptor, Barycentric_coordinates>& f_bc)
{
std::cout << "#" << ++i << " Face: " << get(CGAL::face_index, g)[f_bc.first] << " , ("
<< f_bc.second[0] << " , "
<< f_bc.second[1] << " , "
<< f_bc.second[2] << ")";
std::cout << " Position: " << Surface_mesh_shortest_path::point(f_bc.first, f_bc.second, g) << "\n";
}
};
int main(int argc, char** argv)
{
const std::string filename = (argc>1) ? argv[1] : CGAL::data_file_path("meshes/elephant.off");
Triangle_mesh tmesh;
if(!CGAL::IO::read_polygon_mesh(filename, tmesh) ||
!CGAL::is_triangle_mesh(tmesh))
{
std::cerr << "Invalid input file." << std::endl;
return EXIT_FAILURE;
}
// pick up a random face
const unsigned int randSeed = argc > 2 ? boost::lexical_cast<unsigned int>(argv[2]) : 7915421;
CGAL::Random rand(randSeed);
const int target_face_index = rand.get_int(0, static_cast<int>(num_faces(tmesh)));
face_iterator face_it = faces(tmesh).first;
std::advance(face_it,target_face_index);
// ... and define a barycentric coordinates inside the face
Barycentric_coordinates 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(tmesh);
std::cout << "Add source: " << Surface_mesh_shortest_path::point(*face_it, face_location, tmesh) << std::endl;
shortest_paths.add_source_point(*face_it, face_location);
// pick a random target point inside a face
face_it = faces(tmesh).first;
std::advance(face_it, rand.get_int(0, static_cast<int>(num_faces(tmesh))));
std::cout << "Target is: " << Surface_mesh_shortest_path::point(*face_it, face_location, tmesh) << std::endl;
// collect the sequence of simplicies crossed by the shortest path
Sequence_collector sequence_collector;
shortest_paths.shortest_path_sequence_to_source_points(*face_it, face_location, sequence_collector);
// print the sequence using the visitor pattern
Print_visitor print_visitor(tmesh);
for (size_t i = 0; i < sequence_collector.sequence.size(); ++i)
std::visit(print_visitor, sequence_collector.sequence[i]);
return 0;
}
Surface_mesh_shortest_path.h
Convenience header file only including CGAL/Surface_mesh_shortest_path/Surface_mesh_shortest_path....
CGAL::Exact_predicates_inexact_constructions_kernel
CGAL::Surface_mesh_shortest_path_traits
A model of the concept SurfaceMeshShortestPathTraits as required by the Surface_mesh_shortest_path cl...
Definition: Surface_mesh_shortest_path_traits.h:43
CGAL::Surface_mesh_shortest_path
Computes shortest surface paths from one or more source points on a surface mesh.
Definition: Surface_mesh_shortest_path.h:73
CGAL::Surface_mesh
CGAL::is_triangle_mesh
bool is_triangle_mesh(const FaceGraph &g)
CGAL::IO::read_polygon_mesh
bool read_polygon_mesh(const std::string &fname, Graph &g, const NamedParameters &np=parameters::default_values())
Kernel