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// Copyright (c) 2012-2013, IGN France.
// Copyright (c) 2012-2024, Oslandia.
// Copyright (c) 2024-2025, SFCGAL team.
// SPDX-License-Identifier: LGPL-2.0-or-later
#include <fstream>
#include <CGAL/Cartesian.h>
#include <CGAL/Point_2.h>
#include <CGAL/Point_3.h>
#include <CGAL/Polygon_2.h>
#include <CGAL/Polygon_with_holes_2.h>
#include <CGAL/Segment_2.h>
#include <CGAL/Segment_3.h>
typedef CGAL::Cartesian<double> Kernel;
typedef Kernel::Vector_2 Vector_2;
typedef Kernel::Vector_3 Vector_3;
typedef Kernel::Point_2 Point_2;
typedef Kernel::Point_3 Point_3;
typedef CGAL::Segment_2<Kernel> Segment_2;
typedef CGAL::Segment_3<Kernel> Segment_3;
typedef CGAL::Polygon_2<Kernel> Polygon_2;
typedef CGAL::Polygon_with_holes_2<Kernel> Polygon_with_holes_2;
#include <CGAL/Delaunay_triangulation_2.h>
#include <CGAL/Triangulation_vertex_base_with_info_2.h>
//-- Info on vertex (unsigned int, an idenfier)
typedef CGAL::Triangulation_vertex_base_with_info_2<unsigned int, Kernel> Vb;
typedef CGAL::Triangulation_data_structure_2<Vb> Tds;
//-- Triangulation
typedef CGAL::Delaunay_triangulation_2<Kernel, Tds> Delaunay_triangulation_2;
//-- point generator
#include <CGAL/point_generators_2.h>
typedef CGAL::Creator_uniform_2<double, Point_2> Creator_2;
/**
* Generate a terrain and export to wavefront obj format
*/
int
main()
{
std::ofstream ofs("triangulation2.obj");
if (!ofs.good()) {
std::cout << "can't open file" << std::endl;
return 1;
}
const size_t n = 1000;
CGAL::Random_points_in_disc_2<Point_2, Creator_2> g(5.0);
//-- triangulate points
Delaunay_triangulation_2 tri;
// create points and associates ids
std::vector<Point_2> points;
for (size_t i = 0; i < n; i++) {
Point_2 point2d = *(++g);
Delaunay_triangulation_2::Vertex_handle v = tri.insert(point2d);
v->info() = i;
points.push_back(point2d);
}
// print vertices
ofs << "# " << tri.number_of_vertices() << " vertices" << std::endl;
for (size_t i = 0; i < n; i++) {
ofs << "v " << points[i] << " 0.0" << std::endl;
}
// print faces
ofs << "# " << tri.number_of_faces() << " faces" << std::endl;
//-- print triangles
// warning : Delaunay_triangulation_2::All_faces_iterator iterator over
// infinite faces
for (Delaunay_triangulation_2::Finite_faces_iterator it =
tri.finite_faces_begin();
it != tri.finite_faces_end(); ++it) {
size_t ia = it->vertex(0)->info();
size_t ib = it->vertex(1)->info();
size_t ic = it->vertex(2)->info();
assert(it->is_valid());
assert(ia < tri.number_of_vertices() || ib < tri.number_of_vertices() ||
ic < tri.number_of_vertices());
ofs << "f " << (ia + 1) << " " << (ib + 1) << " " << (ic + 1) << std::endl;
}
return 0;
}
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