CGAL users discussion list

[Peter Hachenberger <>]

Hi Stephen,

Bart and I had some email chat about that. He basically removed all
those geometric assertion and it seems to work. 

Peter

On Thu, 2008-01-24 at 18:42 -0800, Stephen Wong wrote:
> Hi Bart,
> 
> Thanks for your help.  I have tried to implement a threshold numbertype 
> based on Gmpq, as you have done.  However, when execution of Boolean 
> operations, CGAL fails at non-assertions on some geometries.  Have you 
> experienced this as well?  The amount of success I have had with removing 
> "thin slabs" using this method is limited - most of the time, I get 
> failures in CGAL's Nef_polyhedron_3.
> 
> Regards,
> 
> Stephen
> 
> 
> -----Original Message-----
> From: 
> 
>  
> [mailto:]
>  On Behalf Of Bart Janssens
> Sent: January-21-08 11:04 PM
> To: 
> 
> Subject: Re: [cgal-discuss] Boolean Operations (Nef_3) creating thin (e-16) 
> slabs
> 
> On 1/21/08, Stephen Wong 
> <>
>  wrote:
> > Is there a way for Nef_polyhedron_3 to remove very thin slabs based on a
> > certain tolerance value?  Rounding the input values will not always solve
> > this problem.
> 
> In K-3D, we solved this by using a custom number type, that compares
> values up to a threshold. See
> http://k3d.svn.sourceforge.net/viewvc/k3d/trunk/modules/booleans/threshold_number.h
> for an example.
> When using this approach, you may run into some failed assertions, see
> http://www.k-3d.org/wiki/CGAL_Boolean_Operations for a patch to remove
> the ones I encountered.
> 
> regards,
> 
> --
> Bart Janssens
> --
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