CGAL 5.6.3 - Surface Mesh Topology

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Surface_mesh_topology/path_homotopy_double_torus.cpp
#include <CGAL/Linear_cell_complex_for_combinatorial_map.h>
#include <CGAL/Linear_cell_complex_constructors.h>
#include <CGAL/Curves_on_surface_topology.h>
#include <CGAL/Path_on_surface.h>
#include <CGAL/draw_face_graph_with_paths.h>
typedef CGAL::Linear_cell_complex_for_combinatorial_map<2,3> LCC_3_cmap;
using namespace CGAL::Surface_mesh_topology;
void create_path_1(Path_on_surface<LCC_3_cmap>& p)
{
p.push_back_by_index(14); // Its starting dart
for (int i=0; i<7; ++i)
{ p.extend_positive_turn(2); } // Extend the path
}
void create_path_2(Path_on_surface<LCC_3_cmap>& p)
{ p.push_back_by_index({202, 206, 335, 317, 322, 69, 62, 414}); }
void create_path_3(Path_on_surface<LCC_3_cmap>& p)
{
p.push_back_by_index(470); // Its starting dart
for (int i=0; i<13; ++i)
{ p.extend_positive_turn(2); } // Extend the path
}
int main(int argc, char** argv)
{
bool draw=(argc>1?std::string(argv[1])=="-draw":false);
LCC_3_cmap lcc;
if (!CGAL::load_off(lcc, CGAL::data_file_path("meshes/double-torus-example.off").c_str()))
{
std::cout<<"ERROR reading file "<< CGAL::data_file_path("meshes/double-torus-example.off") << std::endl;
exit(EXIT_FAILURE);
}
Curves_on_surface_topology<LCC_3_cmap> cst(lcc);
Path_on_surface<LCC_3_cmap> p1(lcc), p2(lcc), p3(lcc);
create_path_1(p1);
create_path_2(p2);
create_path_3(p3);
bool res1=cst.is_contractible(p1);
std::cout<<"Path p1 (pink) "<<(res1?"IS":"IS NOT")
<<" contractible."<<std::endl;
bool res2=cst.are_freely_homotopic(p1, p2);
std::cout<<"Path p1 (pink) "<<(res2?"IS":"IS NOT")
<<" homotopic with path p2 (green)."<<std::endl;
bool res3=cst.are_freely_homotopic(p1, p3);
std::cout<<"Path p1 (pink) "<<(res3?"IS":"IS NOT")
<<" homotopic with path p3 (orange)."<<std::endl;
if (draw)
{ CGAL::draw(lcc, {p1, p2, p3}); }
return EXIT_SUCCESS;
}
CGAL::Linear_cell_complex_for_combinatorial_map
CGAL::Surface_mesh_topology::Curves_on_surface_topology
The class Curves_on_surface_topology provides methods to compute shortest non contractible cycles and...
Definition: Curves_on_surface_topology.h:13
CGAL::Surface_mesh_topology::Path_on_surface
The class Path_on_surface represents a walk in a mesh which is either a model of CombinatorialMap,...
Definition: Path_on_surface.h:13
CGAL::Surface_mesh_topology::Path_on_surface::extend_positive_turn
void extend_positive_turn(std::size_t nb)
adds the dart/halfedge obtained by turning nb times around the target vertex of the last dart/halfedg...
CGAL::Surface_mesh_topology::Path_on_surface::push_back_by_index
void push_back_by_index(std::size_t i)
adds the dart/halfedge with index i at the end of this path.
CGAL::draw
void draw(const LCC &alcc)
draw
void draw(const SM &asm)
CGAL::Surface_mesh_topology
Definition: Curves_on_surface_topology.h:3