\( \newcommand{\E}{\mathrm{E}} \) \( \newcommand{\A}{\mathrm{A}} \) \( \newcommand{\R}{\mathrm{R}} \) \( \newcommand{\N}{\mathrm{N}} \) \( \newcommand{\Q}{\mathrm{Q}} \) \( \newcommand{\Z}{\mathrm{Z}} \) \( \def\ccSum #1#2#3{ \sum_{#1}^{#2}{#3} } \def\ccProd #1#2#3{ \sum_{#1}^{#2}{#3} }\)
CGAL 5.0.3 - Triangulated Surface Mesh Simplification
Surface_mesh_simplification/edge_collapse_enriched_polyhedron.cpp
#include <iostream>
#include <fstream>
#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/Count_ratio_stop_predicate.h>
typedef Kernel::Point_3 Point;
// Setup an enriched polyhedron type which stores an id() field in the items
typedef boost::graph_traits<Surface_mesh>::halfedge_descriptor halfedge_descriptor;
typedef boost::graph_traits<Surface_mesh>::vertex_descriptor vertex_descriptor;
int main( int argc, char** argv )
{
Surface_mesh surface_mesh;
std::ifstream is(argv[1]);
is >> surface_mesh;
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 10% of the initial count
SMS::Count_ratio_stop_predicate<Surface_mesh> stop(0.1);
// 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, ommited in
// the previous example.
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 > 2 ? argv[2] : "out.off" );
os.precision(17);
os << surface_mesh;
return EXIT_SUCCESS;
}