CGAL users discussion list

["Laurent Rineau (CGAL/GeometryFactory)" <>]

Le Tuesday 25 March 2014 13:45:24 Benjamin Kehlet a écrit :
> Dear CGAL community
> 
> When attempting to generate tetrahedral meshes from polyhedral
> domains, I sometimes experience program crashes. However, a very minor
> change in the meshing may change this. So I wonder if there are any
> preconditions related to the meshing criteria that I am violating? Or
> if I am doing something else wrong.
[...]

Hi Benjamin,

You did nothing wrong. There was a bug in the code of Mesh_3. That ruined by 
whole Friday, and part of today, to find it. I have commited the attached 
patch, in CGAL Git repository. I will try to integrate it in CGAL-4.4 before 
it is released.

You can apply the patch on top of CGAL-4.4-beta1, with the following shell 
command, run inside the source tree of CGAL.

  patch -p2 < Mesh_3.patch

If you do not have the patch command, you can apply it manually. There is 
only 
two lines to change. I hope that will solve all you issues.

-- 
Laurent Rineau, PhD
R&D Engineer at GeometryFactory           http://www.geometryfactory.com/
Release Manager of the CGAL Project       http://www.cgal.org/
commit 6649036c8071316735bab8ae5730ad6bcd2f3741
Author: Laurent Rineau <>
Date:   Mon Mar 31 15:41:51 2014 +0200

    Fix a bug in Mesh_3
    
    Benjamin Kehlet reported on CGAL-discuss (Tue, 25 Mar 2014 13:45:24
    +0100) that Mesh_3 was not able to mesh the simple following OFF:
    
    OFF
    4 4 0
    
    0 0 0
    0 0 1
    0 1 0
    1 0 0
    3  3 1 2
    3  0 1 3
    3  0 3 2
    3  0 2 1
    
    The unit tetrahedron!!
    
    The bug was in the robust weighted circumcenter traits. The traits
    checks that the circumcenter of four points is at least in the circum
    sphere of the four points. But for weighted points, that is
    "power_test" that must be tested, instead of "side_of_oriented_sphere".

diff --git a/Mesh_3/include/CGAL/Mesh_3/Robust_weighted_circumcenter_filtered_traits_3.h b/Mesh_3/include/CGAL/Mesh_3/Robust_weighted_circumcenter_filtered_traits_3.h
index 8d8fdba..d5e7012 100644
--- a/Mesh_3/include/CGAL/Mesh_3/Robust_weighted_circumcenter_filtered_traits_3.h
+++ b/Mesh_3/include/CGAL/Mesh_3/Robust_weighted_circumcenter_filtered_traits_3.h
@@ -169,10 +169,9 @@ public:
   {
     CGAL_precondition(Rt().orientation_3_object()(p,q,r,s) == CGAL::POSITIVE);
     
-    // We use Side_of_oriented_sphere_3: it is static filtered and
+    // We use Power_test_3: it is static filtered and
     // we know that p,q,r,s are positive oriented
-    typename Rt::Side_of_oriented_sphere_3 side_of_oriented_sphere =
-      Rt().side_of_oriented_sphere_3_object();
+    typename Rt::Power_test_3 power_test = Rt().power_test_3_object();
 
     // Compute denominator to swith to exact if it is 0
     FT num_x, num_y, num_z, den;
@@ -188,7 +187,7 @@ public:
       Bare_point res(p.x() + num_x*inv, p.y() - num_y*inv, p.z() + num_z*inv);
       
       // Fast output
-      if ( side_of_oriented_sphere(p,q,r,s,res) == CGAL::ON_POSITIVE_SIDE )
+      if ( power_test(p,q,r,s,res) == CGAL::ON_POSITIVE_SIDE )
         return res;
     }