Polygon_mesh_processing/mesh_slicer_example.cpp

#include <CGAL/Exact_predicates_inexact_constructions_kernel.h>
#include <CGAL/Surface_mesh.h>
#include <CGAL/AABB_halfedge_graph_segment_primitive.h>
#include <CGAL/AABB_tree.h>
#include <CGAL/AABB_traits.h>

#include <CGAL/Polygon_mesh_slicer.h>

#include <fstream>

typedef CGAL::Exact_predicates_inexact_constructions_kernel K;
typedef CGAL::Surface_mesh<K::Point_3> Mesh;

typedef std::vector<K::Point_3> Polyline_type;
typedef std::list< Polyline_type > Polylines;

typedef CGAL::AABB_halfedge_graph_segment_primitive<Mesh> HGSP;
typedef CGAL::AABB_traits<K, HGSP>    AABB_traits;
typedef CGAL::AABB_tree<AABB_traits>  AABB_tree;

int main(int argc, char* argv[])
{
  const char* filename = (argc > 1) ? argv[1] : "data/eight.off";
  std::ifstream input(filename);

  Mesh mesh;
  if (!input || !(input >> mesh) || mesh.is_empty()
             || !CGAL::is_triangle_mesh(mesh)) {
    std::cerr << "Not a valid input file." << std::endl;
    return 1;
  }

  // Slicer constructor from the mesh
  CGAL::Polygon_mesh_slicer<Mesh, K> slicer(mesh);

  Polylines polylines;
  slicer(K::Plane_3(0, 0, 1, -0.4), std::back_inserter(polylines));
  std::cout << "At z = 0.4, the slicer intersects "
            << polylines.size() << " polylines" << std::endl;
  polylines.clear();

  slicer(K::Plane_3(0, 0, 1, 0.2), std::back_inserter(polylines));
  std::cout << "At z = -0.2, the slicer intersects "
            << polylines.size() << " polylines" << std::endl;
  polylines.clear();

  // Use the Slicer constructor from a pre-built AABB_tree
  AABB_tree tree(edges(mesh).first, edges(mesh).second, mesh);
  CGAL::Polygon_mesh_slicer<Mesh, K> slicer_aabb(mesh, tree);
  slicer_aabb(K::Plane_3(0, 0, 1, -0.4), std::back_inserter(polylines));
  std::cout << "At z = 0.4, the slicer intersects "
            << polylines.size() << " polylines" << std::endl;
  polylines.clear();

  return 0;
}