CGAL users discussion list

[Raphael Grimm <>]

Hi,

I wanted to compare different methods to turn implicit surfaces into a mesh.

In the attached code I compared CGAL::make_mesh_3 with 
CGAL::make_surface_mesh.
I can deactivate the code using either of these functions using the 
defines at the top of the file.

If  I activate only one of these functions, the executable generates the 
meshes.
So far all is good.

If I activate both functions to do the conversion, the executable segfaults:

void impl_mesh_via_all(double) 4
void impl_mesh_via_make_surface_mesh(double) 4
    impl
    convert
    save
void impl_mesh_via_make_mesh_3(double) 4
    impl
    convert
Segmentation fault (core dumped)


I do not understand this, since both functions work if I only use one in 
the executable.
Can anyone tell me what the reason for this is?

Best Regards,
Raphael

--
Karlsruhe Institute of Technology (KIT)
Institute for Anthropomatics and Robotics (IAR)
High Performance Humanoid Technologies (H2T)

Raphael Grimm (M.Sc.)
Research Scientist

Adenauerring 2
Building 50.20, Room 334
76131 Karlsruhe, Germany

Phone: +49 721 608-47133
Fax: +49 721 608-48270
Email: 

Web: http://h2t.anthropomatik.kit.edu/

KIT - The Research University in the Helmholtz Association

#define build_make_mesh_3
#define build_make_surface_mesh

#include <fstream>
#include <boost/current_function.hpp>

#ifdef build_make_mesh_3
#include <CGAL/Mesh_complex_3_in_triangulation_3.h>
#include <CGAL/Mesh_triangulation_3.h>
#include <CGAL/Mesh_criteria_3.h>
#include <CGAL/Implicit_mesh_domain_3.h>
#include <CGAL/make_mesh_3.h>
#include <CGAL/IO/facets_in_complex_3_to_triangle_mesh.h>
#endif

#ifdef build_make_surface_mesh
#include <CGAL/Surface_mesh_default_triangulation_3.h>
#include <CGAL/Complex_2_in_triangulation_3.h>
#include <CGAL/make_surface_mesh.h>
#include <CGAL/Implicit_surface_3.h>
#include <CGAL/IO/facets_in_complex_2_to_triangle_mesh.h>
#endif

#include <CGAL/Exact_predicates_inexact_constructions_kernel.h>

#include <CGAL/Polyhedron_3.h>
using Poly = CGAL::Polyhedron_3<CGAL::Epick>;
using ResultT = Poly;

using Sphere_3  = typename CGAL::Epick::Sphere_3;
using Point_3   = typename CGAL::Epick::Point_3 ;

using Function = double (*)(const Point_3&);
double sphere_function (const Point_3& p)
{
    return CGAL::squared_distance(p, Point_3(CGAL::ORIGIN))-1;
}

// //////////////////////////////////////////////////////////////////////////// //
// //////////////////////////////// make_mesh_3 /////////////////////////////// //
// //////////////////////////////////////////////////////////////////////////// //
#ifdef build_make_mesh_3

void impl_mesh_via_make_mesh_3(double r)
{
    std::cout << BOOST_CURRENT_FUNCTION << " " << r << std::endl;
    using impl_mesh = CGAL::Implicit_mesh_domain_3<Function, CGAL::Epick>;
    using Traits = CGAL::Mesh_triangulation_3<impl_mesh,CGAL::Default, CGAL::Sequential_tag>::type;
    using C3t3 = CGAL::Mesh_complex_3_in_triangulation_3<Traits>;
    std::cout << "    impl" << std::endl;
    impl_mesh impl(sphere_function, Sphere_3(CGAL::ORIGIN, r));
    std::cout << "    convert" << std::endl;
    CGAL::Mesh_criteria_3<Traits> criteria(
        CGAL::parameters::facet_angle            = 30,
        CGAL::parameters::facet_size             = 0.1,
        CGAL::parameters::facet_distance         = 0.025,
        CGAL::parameters::cell_radius_edge_ratio = 2,
        CGAL::parameters::cell_size              = 0.1
    );
    C3t3 c3t3 = CGAL::make_mesh_3<C3t3>(impl, criteria);
    std::cout << "    save" << std::endl;
    ResultT result;
    CGAL::facets_in_complex_3_to_triangle_mesh(c3t3, result);
    const std::string file = "sphere_impl_mesh_via_make_mesh_3_r_" + std::to_string(r) + ".off";
    std::ofstream{file} << result;
}
#endif
// //////////////////////////////////////////////////////////////////////////// //
// ///////////////////////////// make_surface_mesh //////////////////////////// //
// //////////////////////////////////////////////////////////////////////////// //
#ifdef build_make_surface_mesh
void impl_mesh_via_make_surface_mesh(double r)
{
    std::cout << BOOST_CURRENT_FUNCTION << " " << r << std::endl;
    using Traits    = typename CGAL::Surface_mesher::Surface_mesh_default_triangulation_3_generator<CGAL::Epick>::Type;
    using C2t3      = CGAL::Complex_2_in_triangulation_3<Traits>;
    using impl_surf = CGAL::Implicit_surface_3<typename Traits::Geom_traits, Function>;
    std::cout << "    impl" << std::endl;
    impl_surf impl(sphere_function, CGAL::Epick::Sphere_3(CGAL::ORIGIN, r));
    std::cout << "    convert" << std::endl;
    Traits tr;
    C2t3 c2t3 (tr);
    CGAL::Surface_mesh_default_criteria_3<Traits> criteria(30, 0.1, 0.1);
    CGAL::make_surface_mesh(c2t3, impl, criteria, CGAL::Non_manifold_tag());
    std::cout << "    save" << std::endl;
    ResultT result;
    CGAL::facets_in_complex_2_to_triangle_mesh(c2t3, result);
    const std::string file = "sphere_impl_mesh_via_make_surface_mesh_r_" + std::to_string(r) + ".off";
    std::ofstream{file} << result;
}
#endif
// //////////////////////////////////////////////////////////////////////////// //
// /////////////////////////////////// exec /////////////////////////////////// //
// //////////////////////////////////////////////////////////////////////////// //
void impl_mesh_via_all(double r)
{
    std::cout << BOOST_CURRENT_FUNCTION << " " << r << std::endl;
#ifdef build_make_surface_mesh
    impl_mesh_via_make_surface_mesh(r);
#endif
#ifdef build_make_mesh_3
    impl_mesh_via_make_mesh_3(r);
#endif
}

int main()
{
    impl_mesh_via_all(4);
    impl_mesh_via_all(8);
    impl_mesh_via_all(16);
    impl_mesh_via_all(32);
    impl_mesh_via_all(64);
    impl_mesh_via_all(128);
    impl_mesh_via_all(256);
    impl_mesh_via_all(512);
    impl_mesh_via_all(1024);
    impl_mesh_via_all(2048);
    return 0;
}

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