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#include <CGAL/Simple_cartesian.h>
#include <CGAL/Surface_mesh.h>
#include <CGAL/Timer.h>
#include <CGAL/Surface_mesh_simplification/edge_collapse.h>
#include <CGAL/Surface_mesh_simplification/Policies/Edge_collapse/Edge_count_stop_predicate.h>
#include <CGAL/Surface_mesh_simplification/Policies/Edge_collapse/LindstromTurk_cost.h>
#include <CGAL/Surface_mesh_simplification/Policies/Edge_collapse/LindstromTurk_placement.h>
#include <CGAL/Surface_mesh_simplification/Policies/Edge_collapse/Bounded_normal_change_filter.h>
#include <iostream>
#include <fstream>
typedef CGAL::Simple_cartesian<double> Kernel;
typedef CGAL::Surface_mesh<Kernel::Point_3> Surface_mesh;
namespace SMS = CGAL::Surface_mesh_simplification;
struct Dummy_placement {
template <typename Profile>
std::optional<typename Profile::Point> operator()(const Profile&) const
{
return std::nullopt;
}
template <typename Profile>
std::optional<typename Profile::Point> operator()(const Profile&, const std::optional<typename Profile::Point>& op) const
{
return op;
}
};
int main(int argc, char** argv)
{
Surface_mesh surface_mesh;
const std::string filename = (argc > 1) ? argv[1] : CGAL::data_file_path("meshes/fold.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;
}
// This is a stop predicate (defines when the algorithm terminates).
// In this example, the simplification stops when the number of undirected edges
// left in the surface mesh drops below the specified number
const std::size_t stop_n = (argc > 2) ? std::stoi(argv[2]) : num_edges(surface_mesh)/2 - 1;
SMS::Edge_count_stop_predicate<Surface_mesh> stop(stop_n);
typedef SMS::LindstromTurk_placement<Surface_mesh> Placement;
CGAL::Timer t;
t.start();
// This the actual call to the simplification algorithm.
// The surface mesh and stop conditions are mandatory arguments.
// The index maps are needed because the vertices and edges
// of this surface mesh lack an "id()" field.
std::cout << "Collapsing edges of mesh: " << filename << ", aiming for " << stop_n << " final edges..." << std::endl;
SMS::Bounded_normal_change_filter<> filter;
SMS::edge_collapse(surface_mesh, stop,
CGAL::parameters::get_cost(SMS::LindstromTurk_cost<Surface_mesh>())
.filter(filter)
.get_placement(Placement()));
std::cout << t.time() << " sec" << std::endl;
CGAL::IO::write_polygon_mesh((argc > 3) ? argv[3] : "out.off", surface_mesh, CGAL::parameters::stream_precision(17));
return EXIT_SUCCESS;
}
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