CGAL users discussion list

["Laurent Rineau (GeometryFactory)" <>]

On Tuesday 09 March 2010 12:59:31 Simon Perkins wrote:
> Dear All
> 
> I'm generating some random Delaunay Triangulations and I ran into a
> Precondition Violation in the Mesh_2 Package. I'm using the CGAL 3.5.1 and
> the Exact_predicates_inexact_constructions kernel.
> 
> I create a Delaunay Triangulation by creating 4 constraints corresponding
> to the sides of a square and then use refine_Delaunay_mesh_2 to generate a
> random Delaunay Triangulation within that square. I then save that
> Triangulation using a custom file format.
> 
> I read in the Triangulation from the file and specify the triangles as
> constraints on a new Triangulation. I then attempt to use
> refine_Delaunay_mesh_2 to further refine this new Triangulation.This is
> when I get the following precondition violation
> 
> terminate called after throwing an instance of 'CGAL::Assertion_exception'
>   what():  CGAL ERROR: assertion violation!
> Expr: orientation(fh->vertex(0)->point(), fh->vertex(1)->point(),
> fh->vertex(2)->point()) != COLLINEAR
> File: /home/simon/usr/local/include/CGAL/Mesh_2/Refine_faces.h
> Line: 275
> Aborted

Hi Simon,

It might be that you do not use a kernel with exact (filtered) predicates. 
You 
may also have encountered a bug that exists in Mesh_2 since a long time, and 
which I fixed last week. The patch will be published in CGAL-3.6 final 
release, at the end of this week. Verify your kernel use, and if it is 
correct, be patient until Thursday or Friday.

-- 
Laurent Rineau, PhD
R&D Engineer at GeometryFactory           http://www.geometryfactory.com/
Release Manager of the CGAL Project       http://www.cgal.org/