CGAL 5.6 - 3D Isosurfacing
Isosurfacing_3/marching_cubes_mesh_offset.cpp
#include <CGAL/AABB_face_graph_triangle_primitive.h>
#include <CGAL/AABB_traits.h>
#include <CGAL/AABB_tree.h>
#include <CGAL/Cartesian_grid_3.h>
#include <CGAL/Cartesian_grid_domain.h>
#include <CGAL/Marching_cubes_3.h>
#include <CGAL/Side_of_triangle_mesh.h>
#include <CGAL/Simple_cartesian.h>
#include <CGAL/Surface_mesh.h>
#include <CGAL/boost/graph/IO/OFF.h>
#include <iostream>
typedef typename Kernel::FT FT;
typedef typename Kernel::Point_3 Point;
typedef typename Kernel::Vector_3 Vector;
typedef CGAL::Surface_mesh<Point> Mesh;
typedef CGAL::AABB_face_graph_triangle_primitive<Mesh> Primitive;
typedef CGAL::AABB_traits<Kernel, Primitive> Traits;
typedef CGAL::AABB_tree<Traits> Tree;
typedef std::vector<Point> Point_range;
typedef std::vector<std::vector<std::size_t>> Polygon_range;
// computes the distance of a point p from the mesh with the use of a AABB_tree
inline Kernel::FT distance_to_mesh(const Tree& tree, const Point& p) {
const Point& x = tree.closest_point(p);
return std::sqrt((p - x).squared_length());
}
int main() {
const std::string input_name = "../../../data/bunny.off";
const int n_voxels = 20;
const FT offset_value = -0.03;
// load the original mesh
Mesh mesh_input;
if (!CGAL::IO::read_OFF(input_name, mesh_input)) {
std::cerr << "Could not read mesh" << std::endl;
exit(-1);
}
// compute the new bounding box
CGAL::Bbox_3 aabb_grid = CGAL::Polygon_mesh_processing::bbox(mesh_input);
Vector aabb_increase_vec = Vector(offset_value + 0.01, offset_value + 0.01, offset_value + 0.01);
aabb_grid += (Point(aabb_grid.xmax(), aabb_grid.ymax(), aabb_grid.zmax()) + aabb_increase_vec).bbox();
aabb_grid += (Point(aabb_grid.xmin(), aabb_grid.ymin(), aabb_grid.zmin()) - aabb_increase_vec).bbox();
// construct AABB tree
Tree tree(mesh_input.faces_begin(), mesh_input.faces_end(), mesh_input);
CGAL::Side_of_triangle_mesh<Mesh, CGAL::GetGeomTraits<Mesh>::type> sotm(mesh_input);
// create the grid
Grid grid(n_voxels, n_voxels, n_voxels, aabb_grid);
for (std::size_t z = 0; z < grid.zdim(); z++) {
for (std::size_t y = 0; y < grid.ydim(); y++) {
for (std::size_t x = 0; x < grid.xdim(); x++) {
const FT pos_x = x * grid.get_spacing()[0] + grid.get_bbox().xmin();
const FT pos_y = y * grid.get_spacing()[1] + grid.get_bbox().ymin();
const FT pos_z = z * grid.get_spacing()[2] + grid.get_bbox().zmin();
const Point p(pos_x, pos_y, pos_z);
// compute the distance
grid.value(x, y, z) = distance_to_mesh(tree, p);
// flip the sign, so the distance is negative inside the mesh
const bool is_inside = (sotm(p) == CGAL::ON_BOUNDED_SIDE);
if (is_inside) {
grid.value(x, y, z) *= -1;
}
}
}
}
// create a domain from the grid
// prepare collections for the result
Point_range points;
Polygon_range polygons;
// execute marching cubes with an isovalue equal to the offset
CGAL::Isosurfacing::make_triangle_mesh_using_marching_cubes(domain, offset_value, points, polygons);
// save the result in the OFF format
CGAL::IO::write_OFF("result.off", points, polygons);
}
CGAL 5.6 - 3D Isosurfacing
Isosurfacing_3/marching_cubes_mesh_offset.cpp
#include <CGAL/AABB_face_graph_triangle_primitive.h>
#include <CGAL/AABB_traits.h>
#include <CGAL/AABB_tree.h>
#include <CGAL/Cartesian_grid_3.h>
#include <CGAL/Cartesian_grid_domain.h>
#include <CGAL/Marching_cubes_3.h>
#include <CGAL/Side_of_triangle_mesh.h>
#include <CGAL/Simple_cartesian.h>
#include <CGAL/Surface_mesh.h>
#include <CGAL/boost/graph/IO/OFF.h>
#include <iostream>
typedef typename Kernel::FT FT;
typedef typename Kernel::Point_3 Point;
typedef typename Kernel::Vector_3 Vector;
typedef CGAL::Surface_mesh<Point> Mesh;
typedef CGAL::AABB_face_graph_triangle_primitive<Mesh> Primitive;
typedef CGAL::AABB_traits<Kernel, Primitive> Traits;
typedef CGAL::AABB_tree<Traits> Tree;
typedef std::vector<Point> Point_range;
typedef std::vector<std::vector<std::size_t>> Polygon_range;
// computes the distance of a point p from the mesh with the use of a AABB_tree
inline Kernel::FT distance_to_mesh(const Tree& tree, const Point& p) {
const Point& x = tree.closest_point(p);
return std::sqrt((p - x).squared_length());
}
int main() {
const std::string input_name = "../../../data/bunny.off";
const int n_voxels = 20;
const FT offset_value = -0.03;
// load the original mesh
Mesh mesh_input;
if (!CGAL::IO::read_OFF(input_name, mesh_input)) {
std::cerr << "Could not read mesh" << std::endl;
exit(-1);
}
// compute the new bounding box
CGAL::Bbox_3 aabb_grid = CGAL::Polygon_mesh_processing::bbox(mesh_input);
Vector aabb_increase_vec = Vector(offset_value + 0.01, offset_value + 0.01, offset_value + 0.01);
aabb_grid += (Point(aabb_grid.xmax(), aabb_grid.ymax(), aabb_grid.zmax()) + aabb_increase_vec).bbox();
aabb_grid += (Point(aabb_grid.xmin(), aabb_grid.ymin(), aabb_grid.zmin()) - aabb_increase_vec).bbox();
// construct AABB tree
Tree tree(mesh_input.faces_begin(), mesh_input.faces_end(), mesh_input);
CGAL::Side_of_triangle_mesh<Mesh, CGAL::GetGeomTraits<Mesh>::type> sotm(mesh_input);
// create the grid
Grid grid(n_voxels, n_voxels, n_voxels, aabb_grid);
for (std::size_t z = 0; z < grid.zdim(); z++) {
for (std::size_t y = 0; y < grid.ydim(); y++) {
for (std::size_t x = 0; x < grid.xdim(); x++) {
const FT pos_x = x * grid.get_spacing()[0] + grid.get_bbox().xmin();
const FT pos_y = y * grid.get_spacing()[1] + grid.get_bbox().ymin();
const FT pos_z = z * grid.get_spacing()[2] + grid.get_bbox().zmin();
const Point p(pos_x, pos_y, pos_z);
// compute the distance
grid.value(x, y, z) = distance_to_mesh(tree, p);
// flip the sign, so the distance is negative inside the mesh
const bool is_inside = (sotm(p) == CGAL::ON_BOUNDED_SIDE);
if (is_inside) {
grid.value(x, y, z) *= -1;
}
}
}
}
// create a domain from the grid
// prepare collections for the result
Point_range points;
Polygon_range polygons;
// execute marching cubes with an isovalue equal to the offset
CGAL::Isosurfacing::make_triangle_mesh_using_marching_cubes(domain, offset_value, points, polygons);
// save the result in the OFF format
CGAL::IO::write_OFF("result.off", points, polygons);
}