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#include <CGAL/Simple_cartesian.h>
#include <CGAL/Surface_mesh.h>
#include <CGAL/Isosurfacing_3/Cartesian_grid_3.h>
#include <CGAL/Isosurfacing_3/dual_contouring_3.h>
#include <CGAL/Isosurfacing_3/Dual_contouring_domain_3.h>
#include <CGAL/Isosurfacing_3/Value_function_3.h>
#include <CGAL/Isosurfacing_3/Gradient_function_3.h>
#include <CGAL/Bbox_3.h>
#include <CGAL/IO/polygon_mesh_io.h>
#include <CGAL/Polygon_mesh_processing/polygon_soup_to_polygon_mesh.h>
#include <cmath>
#include <iostream>
#include <vector>
using Kernel = CGAL::Simple_cartesian<double>;
using FT = typename Kernel::FT;
using Point = typename Kernel::Point_3;
using Vector = typename Kernel::Vector_3;
using Grid = CGAL::Isosurfacing::Cartesian_grid_3<Kernel>;
using Values = CGAL::Isosurfacing::Value_function_3<Grid>;
using Gradients = CGAL::Isosurfacing::Gradient_function_3<Grid>;
using Domain = CGAL::Isosurfacing::Dual_contouring_domain_3<Grid, Values, Gradients>;
using Point_range = std::vector<Point>;
using Polygon_range = std::vector<std::vector<std::size_t> >;
using Mesh = CGAL::Surface_mesh<Point>;
// "Devil" - https://www-sop.inria.fr/galaad/surface/
auto devil_value = [](const Point& point)
{
const FT x = point.x(), y = point.y(), z = point.z();
return x*x*x*x + 2*x*x*z*z - 0.36*x*x - y*y*y*y + 0.25*y*y + z*z*z*z;
};
auto devil_gradient = [](const Point& point)
{
const FT x = point.x(), y = point.y(), z = point.z();
const FT gx = 4*x*x*x + 4*x*z*z - 0.72*x;
const FT gy = -4*y*y*y + 0.5*y;
const FT gz = 4*x*x*z + 4*z*z*z;
Vector g(gx, gy, gz);
return g / std::sqrt(gx*gx + gy*gy + gz*gz);
};
int main(int argc, char** argv)
{
const FT isovalue = (argc > 1) ? std::stod(argv[1]) : 0;
const FT box_c = (argc > 2) ? std::abs(std::stod(argv[2])) : 1.;
const std::size_t grid_n = (argc > 3) ? std::stoi(argv[3]) : 50;
// create bounding box and grid
const CGAL::Bbox_3 bbox { -box_c, -box_c, -box_c, box_c, box_c, box_c };
Grid grid { bbox, CGAL::make_array<std::size_t>(grid_n, grid_n, grid_n) };
std::cout << "Span: " << grid.span() << std::endl;
std::cout << "Cell dimensions: " << grid.spacing()[0] << " " << grid.spacing()[1] << " " << grid.spacing()[2] << std::endl;
std::cout << "Cell #: " << grid.xdim() << ", " << grid.ydim() << ", " << grid.zdim() << std::endl;
// fill up values & gradients
Values values { devil_value, grid };
Gradients gradients { devil_gradient, grid };
// Below is equivalent to:
// Domain domain { grid, values, gradients };
Domain domain = CGAL::Isosurfacing::create_dual_contouring_domain_3(grid, values, gradients);
Point_range points;
Polygon_range triangles;
// run dual contouring isosurfacing
std::cout << "Running Dual Contouring with isovalue = " << isovalue << std::endl;
CGAL::Isosurfacing::dual_contouring<CGAL::Parallel_if_available_tag>(domain, isovalue, points, triangles,
CGAL::parameters::do_not_triangulate_faces(true)
.constrain_to_cell(false));
std::cout << "Soup #vertices: " << points.size() << std::endl;
std::cout << "Soup #triangles: " << triangles.size() << std::endl;
if(!CGAL::Polygon_mesh_processing::is_polygon_soup_a_polygon_mesh(triangles)) {
std::cerr << "Warning: the soup is not a 2-manifold surface, non-manifoldness?..." << std::endl;
return EXIT_FAILURE;
}
std::cout << "Create the mesh..." << std::endl;
Mesh mesh;
CGAL::Polygon_mesh_processing::polygon_soup_to_polygon_mesh(points, triangles, mesh);
CGAL::IO::write_polygon_mesh("dual_contouring.off", mesh, CGAL::parameters::stream_precision(17));
std::cout << "Done" << std::endl;
return EXIT_SUCCESS;
}
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