CGAL 6.1.1 - Polygon Mesh Processing

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Polygon_mesh_processing/locate_example.cpp
#include <CGAL/Exact_predicates_inexact_constructions_kernel.h>
#include <CGAL/Surface_mesh.h>
#include <CGAL/Polygon_mesh_processing/locate.h>
#include <CGAL/Polygon_mesh_processing/triangulate_faces.h>
#include <CGAL/AABB_face_graph_triangle_primitive.h>
#include <CGAL/AABB_tree.h>
#include <CGAL/AABB_traits_3.h>
#include <CGAL/boost/graph/helpers.h>
#include <CGAL/Dynamic_property_map.h>
typedef CGAL::Exact_predicates_inexact_constructions_kernel K;
typedef K::FT FT;
typedef K::Point_2 Point_2;
typedef K::Ray_2 Ray_2;
typedef K::Point_3 Point_3;
typedef K::Ray_3 Ray_3;
typedef CGAL::Surface_mesh<Point_3> Mesh;
typedef typename boost::graph_traits<Mesh>::vertex_descriptor vertex_descriptor;
typedef typename boost::graph_traits<Mesh>::face_descriptor face_descriptor;
namespace CP = CGAL::parameters;
namespace PMP = CGAL::Polygon_mesh_processing;
typedef PMP::Barycentric_coordinates<FT> Barycentric_coordinates;
typedef PMP::Face_location<Mesh, FT> Face_location;
int main(int /*argc*/, char** /*argv*/)
{
// Generate a simple 3D triangle mesh that with vertices on the plane xOy
Mesh tm;
CGAL::make_grid(10, 10, tm);
PMP::triangulate_faces(tm);
// Basic usage
Face_location random_location = PMP::random_location_on_mesh<FT>(tm);
const face_descriptor f = random_location.first;
const Barycentric_coordinates& coordinates = random_location.second;
std::cout << "Random location on the mesh: face " << f
<< " and with coordinates [" << coordinates[0] << "; "
<< coordinates[1] << "; "
<< coordinates[2] << "]\n";
std::cout << "It corresponds to point (" << PMP::construct_point(random_location, tm) << ")\n\n";
// Locate a known 3D point in the mesh
const Point_3 query(1.2, 7.4, 0);
Face_location query_location = PMP::locate(query, tm);
std::cout << "Point (" << query << ") is located in face " << query_location.first
<< " with barycentric coordinates [" << query_location.second[0] << "; "
<< query_location.second[1] << "; "
<< query_location.second[2] << "]\n\n";
// Locate a 3D point in the mesh as the intersection of the mesh and a 3D ray.
// The AABB tree can be cached in case many queries are performed (otherwise, it is rebuilt
// on each call, which is expensive).
typedef CGAL::AABB_face_graph_triangle_primitive<Mesh> AABB_face_graph_primitive;
typedef CGAL::AABB_traits_3<K, AABB_face_graph_primitive> AABB_face_graph_traits;
CGAL::AABB_tree<AABB_face_graph_traits> tree;
PMP::build_AABB_tree(tm, tree);
const Ray_3 ray_3(Point_3(4.2, 6.8, 2.4), Point_3(7.2, 2.3, -5.8));
Face_location ray_location = PMP::locate_with_AABB_tree(ray_3, tree, tm);
std::cout << "Intersection of the 3D ray and the mesh is in face " << ray_location.first
<< " with barycentric coordinates [" << ray_location.second[0] << " "
<< ray_location.second[1] << " "
<< ray_location.second[2] << "]\n";
std::cout << "It corresponds to point (" << PMP::construct_point(ray_location, tm) << ")\n";
std::cout << "Is it on the face's border? " << (PMP::is_on_face_border(ray_location, tm) ? "Yes" : "No") << "\n\n";
// -----------------------------------------------------------------------------------------------
// Now, we artificially project the mesh to the natural 2D dimensional plane, with a little translation
// via a custom vertex point property map
typedef CGAL::dynamic_vertex_property_t<Point_2> Point_2_property;
typedef typename boost::property_map<Mesh, Point_2_property>::type Projection_pmap;
Projection_pmap projection_pmap = get(Point_2_property(), tm);
for(vertex_descriptor v : vertices(tm))
{
const Point_3& p = tm.point(v);
put(projection_pmap, v, Point_2(p.x() + 1, p.y())); // simply ignoring the z==0 coordinate and translating along Ox
}
// Locate the same 3D point but in a 2D context
const Point_2 query_2(query.x() + 1, query.y());
Face_location query_location_2 = PMP::locate(query_2, tm, CP::vertex_point_map(projection_pmap));
std::cout << "Point (" << query_2 << ") is located in face " << query_location_2.first
<< " with barycentric coordinates [" << query_location_2.second[0] << "; "
<< query_location_2.second[1] << "; "
<< query_location_2.second[2] << "]\n\n";
// Shoot a 2D ray and locate the intersection with the mesh in 2D
const Ray_2 ray_2(Point_2(-10, -10), Point_2(10, 10));
Face_location ray_location_2 = PMP::locate(ray_2, tm, CP::vertex_point_map(projection_pmap)); // This rebuilds an AABB tree on each call
std::cout << "Intersection of the 2D ray and the mesh is in face " << ray_location_2.first
<< " with barycentric coordinates [" << ray_location_2.second[0] << "; "
<< ray_location_2.second[1] << "; "
<< ray_location_2.second[2] << "]\n";
std::cout << "It corresponds to point (" << PMP::construct_point(ray_location_2, tm, CP::vertex_point_map(projection_pmap)) << ")\n";
if(PMP::is_on_mesh_border(ray_location_2, tm))
std::cout << "It is on the border of the mesh!\n" << std::endl;
return EXIT_SUCCESS;
}
CGAL::AABB_face_graph_triangle_primitive
CGAL::AABB_traits_3
CGAL::AABB_tree
CGAL::Exact_predicates_inexact_constructions_kernel
CGAL::Surface_mesh
CGAL::make_grid
boost::graph_traits< Graph >::halfedge_descriptor make_grid(typename boost::graph_traits< Graph >::vertices_size_type i, typename boost::graph_traits< Graph >::vertices_size_type j, Graph &g, const CoordinateFunctor &calculator, bool triangulated=false)
CGAL::parameters
CGAL::dynamic_vertex_property_t