add approximation and extraction example

Surface_mesh_approximation/examples/Surface_mesh_approximation/CMakeLists.txt

@@ -42,4 +42,5 @@ include_directories( BEFORE ../../include )
 include( CGAL_CreateSingleSourceCGALProgram )
 
 create_single_source_cgal_program( "vsa_extraction_example.cpp" )
+create_single_source_cgal_program( "vsa_approximation_and_extraction_example.cpp" )
 create_single_source_cgal_program( "vsa_metric_example.cpp")

Surface_mesh_approximation/examples/Surface_mesh_approximation/vsa_approximation_and_extraction_example.cpp

@@ -0,0 +1,84 @@
+#include <CGAL/Exact_predicates_inexact_constructions_kernel.h>
+#include <CGAL/Polyhedron_3.h>
+#include <CGAL/boost/graph/graph_traits_Polyhedron_3.h>
+#include <CGAL/IO/Polyhedron_iostream.h>
+#include <CGAL/property_map.h>
+
+#include <iostream>
+#include <fstream>
+#include <CGAL/vsa_mesh_approximation.h>
+#include <CGAL/vsa_mesh_approximation_traits.h>
+
+typedef CGAL::Exact_predicates_inexact_constructions_kernel Kernel;
+typedef CGAL::Polyhedron_3<Kernel> Polyhedron;
+typedef Kernel::FT FT;
+typedef Kernel::Vector_3 Vector_3;
+typedef Kernel::Point_3 Point_3;
+typedef Polyhedron::Facet_const_handle Facet_const_handle;
+typedef Polyhedron::Halfedge_const_handle Halfedge_const_handle;
+typedef Polyhedron::Facet_const_iterator Facet_const_iterator;
+typedef boost::associative_property_map<std::map<Facet_const_handle, Vector_3> > FacetNormalMap;
+typedef boost::associative_property_map<std::map<Facet_const_handle, FT> > FacetAreaMap;
+typedef boost::property_map<Polyhedron, boost::vertex_point_t>::type VertexPointMap;
+
+typedef CGAL::PlaneProxy<Polyhedron> PlaneProxy;
+typedef CGAL::L21Metric<PlaneProxy, FacetNormalMap, FacetAreaMap> L21Metric;
+typedef CGAL::L21ProxyFitting<PlaneProxy, L21Metric, FacetNormalMap, FacetAreaMap> L21ProxyFitting;
+typedef CGAL::PlaneFitting<Polyhedron, FacetAreaMap, FacetNormalMap, VertexPointMap> PlaneFitting;
+typedef CGAL::L21ApproximationTrait<PlaneProxy, Polyhedron, L21Metric, L21ProxyFitting, PlaneFitting, VertexPointMap, FacetNormalMap, FacetAreaMap> L21ApproximationTrait;
+
+int main(int argc, char *argv[])
+{
+  if (argc < 5)
+    return 0;
+
+  // create and read Polyhedron
+  Polyhedron mesh;
+  std::ifstream input(argv[1]);
+  if (!input || !(input >> mesh) || mesh.empty()) {
+    std::cerr << "Invalid off file." << std::endl;
+    return EXIT_FAILURE;
+  }
+
+  // construct facet normal & area map
+  std::map<Facet_const_handle, Vector_3> facet_normals;
+  std::map<Facet_const_handle, FT> facet_areas;
+  for(Facet_const_iterator fitr = mesh.facets_begin(); fitr != mesh.facets_end(); ++fitr) {
+    const Halfedge_const_handle he = fitr->halfedge();
+    const Point_3 p1 = he->opposite()->vertex()->point();
+    const Point_3 p2 = he->vertex()->point();
+    const Point_3 p3 = he->next()->vertex()->point();
+    Vector_3 normal = CGAL::unit_normal(p1, p2, p3);
+    facet_normals.insert(std::pair<Facet_const_handle, Vector_3>(fitr, normal));
+    FT area(std::sqrt(CGAL::to_double(CGAL::squared_area(p1, p2, p3))));
+    facet_areas.insert(std::pair<Facet_const_handle, FT>(fitr, area));
+  }
+  FacetNormalMap normal_pmap(facet_normals);
+  FacetAreaMap area_pmap(facet_areas);
+  VertexPointMap point_pmap = get(boost::vertex_point, const_cast<Polyhedron &>(mesh));
+
+  // create a property-map for segment-ids
+  typedef std::map<Facet_const_handle, std::size_t> Facet_id_map;
+  Facet_id_map internal_facet_id_map;
+  for (Facet_const_iterator fitr = mesh.facets_begin(); fitr != mesh.facets_end(); ++fitr)
+    internal_facet_id_map.insert(std::pair<Facet_const_handle, std::size_t>(fitr, 0));
+  boost::associative_property_map<Facet_id_map> proxy_patch_map(internal_facet_id_map);
+
+  const std::size_t num_proxies = std::atoi(argv[3]);
+  const std::size_t num_iterations = std::atoi(argv[4]);
+  std::vector<int> tris;
+  std::vector<Kernel::Point_3> anchor_pos;
+  int init = std::atoi(argv[2]);
+  if (init < 0 || init > 3)
+    return EXIT_FAILURE;
+  CGAL::vsa_mesh_approximation(mesh,
+    proxy_patch_map,
+    tris,
+    anchor_pos,
+    L21ApproximationTrait(mesh, point_pmap, normal_pmap, area_pmap),
+    init,
+    num_proxies,
+    num_iterations);
+
+  return EXIT_SUCCESS;
+}