CGAL users discussion list

["Sebastien Loriot (GeometryFactory)" <>]

This algorithm requires constructions so you need to use an Kernel with
exact constructions (http://www.cgal.org/FAQ.html#inexact_NT).

Replacing Exact_predicates_inexact_constructions_kernel by
Exact_predicates_exact_constructions_kernel makes your example
running fine on my machine.

Sebastien.

François-Xavier Coudert wrote:
> Sorry for the first email, which was incomplete. I didn't even quote the 
> error message! The code described below compiles OK, but when run it gives:
>
> CGAL error: assertion violation!
> Expression : 
> File       : /opt/CGAL-3.9/include/CGAL/Skin_surface_base_3.h
> Line       : 483
> Explanation: intersection: no intersection.
>
>
> Can someone help me track down that issue?
>
> Thanks in advance,
> FX
>
>
>
>
>
>
> Le 29 nov. 2011 à 13:05, FX a écrit :
>
> > Dear CGAL team and users,
> >
> > I have encountered an assertion violation in CGAL's meshing the union of a 
> > set of balls. I have reduced my much larger original code to a minimal 
> > testcase that always fails on my system. The following testcase tries to mesh 
> > the union of 4 balls:
> >
> > > #include <CGAL/Exact_predicates_inexact_constructions_kernel.h>
> > > #include <CGAL/Skin_surface_3.h>
> > > #include <CGAL/Union_of_balls_3.h>
> > > #include <CGAL/Polyhedron_3.h>
> > > #include <CGAL/mesh_skin_surface_3.h>
> > > #include <CGAL/subdivide_skin_surface_mesh_3.h>
> > > #include <CGAL/IO/Polyhedron_iostream.h>
> > >
> > > int main (void)
> > > {
> > > typedef CGAL::Exact_predicates_inexact_constructions_kernel K;
> > > typedef CGAL::Skin_surface_traits_3<K> Traits;
> > > typedef CGAL::Union_of_balls_3<Traits> Skin_surface_3;
> > > typedef Skin_surface_3::FT FT;
> > > typedef Skin_surface_3::Weighted_point Weighted_point;
> > > typedef Weighted_point::Point Bare_point;
> > > typedef CGAL::Polyhedron_3<K, 
> > > CGAL::Skin_surface_polyhedral_items_3<Skin_surface_3> > Polyhedron;
> > >
> > > std::list<Weighted_point> list;
> > > list.push_front(Weighted_point(Bare_point(0.30700,  6.45800,  6.45800), 1)); 
> > > list.push_front(Weighted_point(Bare_point(0.07400,  5.03900,  5.03900), 1)); 
> > > list.push_front(Weighted_point(Bare_point(0.30700, 19.37400, 19.37400), 1)); 
> > > list.push_front(Weighted_point(Bare_point(0.07400, 20.79300, 20.79300), 1)); 
> > >
> > > Polyhedron p;
> > > Skin_surface_3 skin_surface(list.begin(), list.end());
> > > CGAL::mesh_skin_surface_3(skin_surface, p);
> > > CGAL::subdivide_skin_surface_mesh_3(skin_surface, p, 1);
> > >
> > > std::cout << "Mesh has " << p.size_of_facets() << " facets" << std::endl;
> > >
> > > return 0;
> > > }
> > I compile it against CGAL-3.9 on a x86_64 Mac OS 10.7 system, with Apple's 
> > default G++ 4.2.1 compiler. Boost is 1.46.1, GMP is 5.0.2, MPFR is 3.1.0 (+ 
> > available patches). The compilation command-line is:
> >
> > > g++ bug.cpp -I/opt/CGAL-3.9/include -I/opt/boost-1.46.1/include -L/opt/CGAL-3.9/lib 
> > > -lCGAL -L/opt/boost-1.46.1/lib -lboost_thread -lmpfr -lgmp -frounding-math && 
> > > ./a.out
> >
> > I hope you can help me understand what's going wrong, and whether I used the 
> > CGAL functions right (I tried to stick to the examples as much as possible).
> >
> > Thanks in advance,
> > FX Coudert
> >
> >
> >
> > PS: the CGAL doc says that GMP and MPFR are recommended, implying that 
> > building without them is possible. However, when I tried to do so, the build 
> > system complains that CGAL_Core depends on GMP, and compilation will not 
> > succeed. Did I miss something?