CGAL 6.2 - 3D Isosurfacing

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Isosurfacing_3/contouring_mesh_offset.cpp
#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/Finite_difference_gradient_3.h>
#include <CGAL/Isosurfacing_3/marching_cubes_3.h>
#include <CGAL/Isosurfacing_3/Marching_cubes_domain_3.h>
#include <CGAL/AABB_face_graph_triangle_primitive.h>
#include <CGAL/AABB_traits_3.h>
#include <CGAL/AABB_tree.h>
#include <CGAL/Bbox_3.h>
#include <CGAL/Polygon_mesh_processing/bbox.h>
#include <CGAL/Side_of_triangle_mesh.h>
#include <CGAL/boost/graph/IO/polygon_mesh_io.h>
#include <CGAL/IO/polygon_soup_io.h>
#include <iostream>
#include <string>
#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 Mesh = CGAL::Surface_mesh<Point>;
using Grid = CGAL::Isosurfacing::Cartesian_grid_3<Kernel>;
using Values = CGAL::Isosurfacing::Value_function_3<Grid>;
using Gradients = CGAL::Isosurfacing::Finite_difference_gradient_3<Kernel>;
using Point_range = std::vector<Point>;
using Polygon_range = std::vector<std::vector<std::size_t> >;
struct Offset_oracle
{
using Primitive = CGAL::AABB_face_graph_triangle_primitive<Mesh>;
using Traits = CGAL::AABB_traits_3<Kernel, Primitive>;
using Tree = CGAL::AABB_tree<Traits>;
private:
const bool is_closed;
const Tree tree;
CGAL::Side_of_triangle_mesh<Mesh, Kernel> sotm;
public:
Offset_oracle(const Mesh& mesh)
: is_closed(CGAL::is_closed(mesh)), tree(mesh.faces_begin(), mesh.faces_end(), mesh), sotm(mesh)
{ }
FT distance(const Point& p) const
{
const Point cp = tree.closest_point(p);
FT d = sqrt((p - cp).squared_length());
if(is_closed && sotm(p) == (CGAL::ON_BOUNDED_SIDE))
d *= -1.0;
return d;
}
};
void run_marching_cubes(const Grid& grid,
const FT offset_value,
const Offset_oracle& offset_oracle)
{
using Domain = CGAL::Isosurfacing::Marching_cubes_domain_3<Grid, Values>;
std::cout << "\n ---- " << std::endl;
std::cout << "Running Marching Cubes with offset value = " << offset_value << std::endl;
// fill up values
auto mesh_distance = [&offset_oracle](const Point& p) { return offset_oracle.distance(p); };
Values values { mesh_distance, grid };
Domain domain { grid, values };
Point_range points;
Polygon_range triangles;
// run marching cubes
std::cout << "Running Marching Cubes with isovalue = " << offset_value << std::endl;
CGAL::Isosurfacing::marching_cubes<CGAL::Parallel_if_available_tag>(domain, offset_value, points, triangles);
std::cout << "Output #vertices (MC): " << points.size() << std::endl;
std::cout << "Output #triangles (MC): " << triangles.size() << std::endl;
CGAL::IO::write_polygon_soup("marching_cubes_offsets.off", points, triangles);
}
void run_dual_contouring(const Grid& grid,
const FT offset_value,
const Offset_oracle& offset_oracle)
{
using Domain = CGAL::Isosurfacing::Dual_contouring_domain_3<Grid, Values, Gradients>;
std::cout << "\n ---- " << std::endl;
std::cout << "Running Dual Contouring with offset value = " << offset_value << std::endl;
// fill up values and gradients
auto mesh_distance = [&offset_oracle](const Point& p) { return offset_oracle.distance(p); };
const FT step = CGAL::approximate_sqrt(grid.spacing().squared_length()) * 0.01;
Values values { mesh_distance, grid };
Gradients gradients { values, step };
Domain domain { grid, values, gradients };
// output containers
Point_range points;
Polygon_range triangles;
// run dual contouring
std::cout << "Running Dual Contouring with isovalue = " << offset_value << std::endl;
CGAL::Isosurfacing::dual_contouring<CGAL::Parallel_if_available_tag>(
domain, offset_value, points, triangles,
CGAL::parameters::do_not_triangulate_faces(true));
std::cout << "Output #vertices (DC): " << points.size() << std::endl;
std::cout << "Output #triangles (DC): " << triangles.size() << std::endl;
CGAL::IO::write_polygon_soup("dual_contouring_mesh_offset.off", points, triangles);
}
int main(int argc, char** argv)
{
const std::string filename = (argc > 1) ? argv[1] : CGAL::data_file_path("meshes/cross.off");
const FT offset_value = (argc > 2) ? std::stod(argv[2]) : 0.2;
if(offset_value < 0)
{
std::cerr << "Offset value must be positive" << std::endl;
return EXIT_FAILURE;
}
Mesh mesh;
if(!CGAL::IO::read_polygon_mesh(filename, mesh) || is_empty(mesh))
{
std::cerr << "Could not read input mesh" << std::endl;
return EXIT_FAILURE;
}
if(CGAL::is_closed(mesh))
std::cout << "Input mesh is closed - using signed distance offset" << std::endl;
else
std::cout << "Input mesh is not closed - using unsigned distance offset" << std::endl;
// construct loose bounding box from input mesh
CGAL::Bbox_3 bbox = CGAL::Polygon_mesh_processing::bbox(mesh);
const FT diag_length = sqrt(CGAL::square(bbox.xmax() - bbox.xmin()) +
CGAL::square(bbox.ymax() - bbox.ymin()) +
CGAL::square(bbox.zmax() - bbox.zmin()));
const FT loose_offset = offset_value + 0.1 * diag_length;
Vector aabb_increase_vec = Vector(loose_offset, loose_offset, loose_offset);
bbox += (Point(bbox.xmax(), bbox.ymax(), bbox.zmax()) + aabb_increase_vec).bbox();
bbox += (Point(bbox.xmin(), bbox.ymin(), bbox.zmin()) - aabb_increase_vec).bbox();
const int nv = 15;
Grid grid { bbox, CGAL::make_array<std::size_t>(nv, nv, nv) };
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;
Offset_oracle offset_oracle(mesh);
run_marching_cubes(grid, offset_value, offset_oracle);
run_dual_contouring(grid, offset_value, offset_oracle);
return EXIT_SUCCESS;
}
CGAL::AABB_face_graph_triangle_primitive
CGAL::AABB_traits_3
CGAL::AABB_tree
CGAL::Bbox_3
CGAL::Bbox_3::ymin
double ymin() const
CGAL::Bbox_3::xmax
double xmax() const
CGAL::Bbox_3::zmin
double zmin() const
CGAL::Bbox_3::zmax
double zmax() const
CGAL::Bbox_3::ymax
double ymax() const
CGAL::Bbox_3::xmin
double xmin() const
CGAL::Isosurfacing::Cartesian_grid_3
The class Cartesian_grid_3 represents a 3D Cartesian grid, that is the partition of an iso-cuboid int...
Definition: Cartesian_grid_3.h:148
CGAL::Isosurfacing::Dual_contouring_domain_3
A domain that can be used as input in the Dual Contouring algorithm.
Definition: Dual_contouring_domain_3.h:52
CGAL::Isosurfacing::Finite_difference_gradient_3
Class template for a gradient that is calculated using finite differences.
Definition: Finite_difference_gradient_3.h:39
CGAL::Isosurfacing::Marching_cubes_domain_3
A domain that can be used with the Marching Cubes algorithm.
Definition: Marching_cubes_domain_3.h:50
CGAL::Isosurfacing::Value_function_3
The class Value_function_3 represents a field of scalars computed using a user-provided unary functio...
Definition: Value_function_3.h:40
CGAL::Side_of_triangle_mesh
Kernel::Point_3
Kernel::Vector_3
CGAL::IO::write_polygon_soup
bool write_polygon_soup(const std::string &fname, const PointRange &points, const PolygonRange &polygons, const NamedParameters &np=parameters::default_values())
CGAL::Polygon_mesh_processing::bbox
CGAL::Bbox_3 bbox(const PolygonMesh &pmesh, const NamedParameters &np=parameters::default_values())
CGAL::square
NT square(const NT &x)
CGAL::sqrt
NT sqrt(const NT &x)
CGAL::is_empty
bool is_empty(const FaceGraph &g)
CGAL::is_closed
bool is_closed(const FaceGraph &g)
CGAL::IO::read_polygon_mesh
bool read_polygon_mesh(const std::string &fname, Graph &g, const NamedParameters &np=parameters::default_values())
CGAL::ON_BOUNDED_SIDE
ON_BOUNDED_SIDE
Kernel
CGAL::Simple_cartesian