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Re: [cgal-discuss] 2D mesh generation doesn't mesh my constrained triangulation


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  • From: Andreas Fabri <>
  • To:
  • Subject: Re: [cgal-discuss] 2D mesh generation doesn't mesh my constrained triangulation
  • Date: Wed, 23 Sep 2009 13:50:13 +0200

Amir Vaxman wrote:
Thank you, I figured it out finally after debugging, worth mentioning in the
docs (or did I miss it?)

Hi Amir,

I think you missed it. Let me quote:

43.2 Meshes

43.2.1 Definitions

A mesh is a partition of a given region into simplices whose shapes and sizes
satisfy several criteria.

The domain is the region that the user wants to mesh. It has to be a bounded
region of the plane.


Source:
http://www.cgal.org/Manual/beta/doc_html/cgal_manual/Mesh_2/Chapter_main.html


andreas



-----Original Message-----
From: Laurent Rineau (GeometryFactory)
[mailto:] Sent: Wednesday, September 23, 2009 1:23 PM
To:

Subject: Re: [cgal-discuss] 2D mesh generation doesn't mesh my constrained
triangulation

Le lundi 21 septembre 2009 20:02:55, Amir Vaxman a écrit :
I enter a constraint triangulation by vertices, and then operate the mesh
generator, but I see no change. A little debugging indicated that there
were no bad faces. I tried it on several outputs which apparently had bad
faces, so it must be something in my definition. My definitions are:

In your constrained triangulation, do the constrained edges form a closed path? The 2D Mesh Generation algorithm needs a meshing domain. By default,
any face that cannot be reached from the infinite faces, without traversing a constrained edge, is inside the domain.

See the figures here:
http://www.cgal.org/Manual/last/doc_html/cgal_manual/Mesh_2/Chapter_main.htm
l#Domain

If the polygons on those figures were not closed, then the meshing domain (painted in green) would be empty. If your constrained edges do not form a closed domain, then you need to insert a bounding box (four constrained
edges) in the constrained triangulation.





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