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#include <CGAL/Simple_cartesian.h>
#include <CGAL/Surface_mesh.h>
// Simplification function
#include <CGAL/Surface_mesh_simplification/edge_collapse.h>
// Midpoint placement policy
#include <CGAL/Surface_mesh_simplification/Policies/Edge_collapse/Midpoint_placement.h>
//Placement wrapper
#include <CGAL/Surface_mesh_simplification/Policies/Edge_collapse/Constrained_placement.h>
// Stop-condition policy
#include <CGAL/Surface_mesh_simplification/Policies/Edge_collapse/Edge_count_stop_predicate.h>
#include <iostream>
#include <fstream>
typedef CGAL::Simple_cartesian<double> Kernel;
typedef Kernel::Point_3 Point_3;
typedef CGAL::Surface_mesh<Point_3> Surface_mesh;
typedef boost::graph_traits<Surface_mesh>::halfedge_descriptor halfedge_descriptor;
typedef boost::graph_traits<Surface_mesh>::edge_descriptor edge_descriptor;
namespace SMS = CGAL::Surface_mesh_simplification;
// BGL property map which indicates whether an edge is marked as non-removable
struct Border_is_constrained_edge_map
{
const Surface_mesh* sm_ptr;
typedef edge_descriptor key_type;
typedef bool value_type;
typedef value_type reference;
typedef boost::readable_property_map_tag category;
Border_is_constrained_edge_map(const Surface_mesh& sm) : sm_ptr(&sm) {}
friend value_type get(const Border_is_constrained_edge_map& m, const key_type& edge) {
return CGAL::is_border(edge, *m.sm_ptr);
}
};
// Placement class
typedef SMS::Constrained_placement<SMS::Midpoint_placement<Surface_mesh>,
Border_is_constrained_edge_map > Placement;
int main(int argc, char** argv)
{
Surface_mesh surface_mesh;
const std::string filename = (argc > 1) ? argv[1] : CGAL::data_file_path("meshes/mesh_with_border.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;
}
Surface_mesh::Property_map<halfedge_descriptor, std::pair<Point_3, Point_3> > constrained_halfedges;
constrained_halfedges = surface_mesh.add_property_map<halfedge_descriptor,std::pair<Point_3, Point_3> >("h:vertices").first;
std::size_t nb_border_edges=0;
for(halfedge_descriptor hd : halfedges(surface_mesh))
{
if(CGAL::is_border(hd, surface_mesh))
{
constrained_halfedges[hd] = std::make_pair(surface_mesh.point(source(hd, surface_mesh)),
surface_mesh.point(target(hd, surface_mesh)));
++nb_border_edges;
}
}
// Contract the surface mesh as much as possible
SMS::Edge_count_stop_predicate<Surface_mesh> stop(0);
Border_is_constrained_edge_map bem(surface_mesh);
// This the actual call to the simplification algorithm.
// The surface mesh and stop conditions are mandatory arguments.
std::cout << "Collapsing as many edges of mesh: " << filename << " as possible..." << std::endl;
int r = SMS::edge_collapse(surface_mesh, stop,
CGAL::parameters::edge_is_constrained_map(bem)
.get_placement(Placement(bem)));
std::cout << "\nFinished!\n" << r << " edges removed.\n"
<< surface_mesh.number_of_edges() << " final edges.\n";
CGAL::IO::write_polygon_mesh((argc > 2) ? argv[2] : "out.off", surface_mesh, CGAL::parameters::stream_precision(17));
// now check!
for(halfedge_descriptor hd : halfedges(surface_mesh))
{
if(CGAL::is_border(hd,surface_mesh))
{
--nb_border_edges;
if(constrained_halfedges[hd] != std::make_pair(surface_mesh.point(source(hd, surface_mesh)),
surface_mesh.point(target(hd, surface_mesh))))
{
std::cerr << "oops. send us a bug report\n";
}
}
}
assert(nb_border_edges==0);
return EXIT_SUCCESS;
}
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