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- From: Thiago Milanetto Schlittler <>
- To:
- Subject: Re: [cgal-discuss] Wrong inexact intersection between 3D triangles
- Date: Mon, 5 Oct 2015 21:47:25 +0200
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> On 05 Oct 2015, at 21:31, Olivier Devillers
> <>
> wrote:
>
> Le 05/10/15 16:59, Thiago Milanetto Schlittler a écrit :
>> Hello!
>>
>> I'm having a really weird bug when trying to intersect two triangles
>> inside a 3D space while using the
>> `CGAL::Exact_predicates_inexact_constructions_kernel` kernel. Essentially,
>> I have two triangles that should not intersect. The function
>> `CGAL::do_intersect` returns always `false` when testing them, but the
>> function `CGAL::intersection` builds an intersection, depending on the
>> order of the vertices of the triangles.
>>
>> The bug disappears when I use the
>> `CGAL::Exact_predicates_exact_constructions_kernel` kernel, but I can't
>> afford to use it in the real case scenario.
> So, it does not look like a bug.
> If you use inexact constructions, constructions are inexact....
While this is true, the triangles are sufficiently far away from each other
to do not create an intersection due to an rounding number error associated
to the inexact constructions (or at least I think so, correct me if I’m wrong
…). I’ve attached a figure and a gmsh .geo file with both triangles. The
triangle A is formed by vertices 1, 2 and 3, B is formed by vertices 11, 12,
13, and the “intersection" found is formed by the segment 21 - 22 (which is
co-planar to the triangle A).
Thanks in advance,
Thiago Milanetto Schlittler
Attachment:
triangle_intersection.geo
Description: Binary data
- [cgal-discuss] Wrong inexact intersection between 3D triangles, Thiago Milanetto Schlittler, 10/05/2015
- Re: [cgal-discuss] Wrong inexact intersection between 3D triangles, Olivier Devillers, 10/05/2015
- Re: [cgal-discuss] Wrong inexact intersection between 3D triangles, Thiago Milanetto Schlittler, 10/05/2015
- Re: [cgal-discuss] Wrong inexact intersection between 3D triangles, Sebastien Loriot (GeometryFactory), 10/06/2015
- Re: [cgal-discuss] Wrong inexact intersection between 3D triangles, Thiago Milanetto Schlittler, 10/06/2015
- Re: [cgal-discuss] Wrong inexact intersection between 3D triangles, Sebastien Loriot (GeometryFactory), 10/06/2015
- Re: [cgal-discuss] Wrong inexact intersection between 3D triangles, Thiago Milanetto Schlittler, 10/05/2015
- Re: [cgal-discuss] Wrong inexact intersection between 3D triangles, Olivier Devillers, 10/05/2015
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