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#include <CGAL/Simple_cartesian.h>
#include <CGAL/Polyhedron_3.h>
// Extended polyhedron items which include an id() field
#include <CGAL/Polyhedron_items_with_id_3.h>
#include <CGAL/Surface_mesh_simplification/edge_collapse.h>
#include <CGAL/Surface_mesh_simplification/Policies/Edge_collapse/Edge_count_ratio_stop_predicate.h>
#include <iostream>
#include <fstream>
typedef CGAL::Simple_cartesian<double> Kernel;
typedef Kernel::Point_3 Point;
// Setup an enriched polyhedron type which stores an id() field in the items
typedef CGAL::Polyhedron_3<Kernel,CGAL::Polyhedron_items_with_id_3> Surface_mesh;
typedef boost::graph_traits<Surface_mesh>::vertex_descriptor vertex_descriptor;
typedef boost::graph_traits<Surface_mesh>::halfedge_descriptor halfedge_descriptor;
namespace SMS = CGAL::Surface_mesh_simplification;
int main(int argc, char** argv)
{
Surface_mesh surface_mesh;
const std::string filename = (argc > 1) ? argv[1] : CGAL::data_file_path("meshes/small_cube.off");
std::ifstream is(filename);
if(!is || !(is >> surface_mesh))
{
std::cerr << "Failed to read input mesh: " << filename << std::endl;
return EXIT_FAILURE;
}
if(!CGAL::is_triangle_mesh(surface_mesh))
{
std::cerr << "Input geometry is not triangulated." << std::endl;
return EXIT_FAILURE;
}
// The items in this polyhedron have an "id()" field
// which the default index maps used in the algorithm
// need to get the index of a vertex/edge.
// However, the Polyhedron_3 class doesn't assign any value to
// this id(), so we must do it here:
int index = 0;
for(halfedge_descriptor hd : halfedges(surface_mesh))
hd->id() = index++;
index = 0;
for(vertex_descriptor vd : vertices(surface_mesh))
vd->id() = index++;
// In this example, the simplification stops when the number of undirected edges
// drops below xx% of the initial count
const double ratio = (argc > 2) ? std::stod(argv[2]) : 0.1;
SMS::Edge_count_ratio_stop_predicate<Surface_mesh> stop(ratio);
// The index maps are not explicitelty passed as in the previous
// example because the surface mesh items have a proper id() field.
// On the other hand, we pass here explicit cost and placement
// function which differ from the default policies, omitted in
// the previous example.
std::cout << "Collapsing edges of mesh: " << filename << ", aiming for " << 100 * ratio << "% of the input edges..." << std::endl;
int r = SMS::edge_collapse(surface_mesh, stop);
std::cout << "\nFinished!\n" << r << " edges removed.\n"
<< (surface_mesh.size_of_halfedges()/2) << " final edges.\n";
std::ofstream os((argc > 3) ? argv[3] : "out.off");
os.precision(17);
os << surface_mesh;
return EXIT_SUCCESS;
}
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