CGAL users discussion list

[Me Myself <>]

Hi Everyone,

It seems that when one renders the regular triangulations output by
refine_mesh, they are either:

1. Not oriented properly
2. Or are not a decomposition of the convex hull of the input
3. Or perhaps I'm missing something after reading this post, since the
original poster had exactly the same problem, but I cant figure out
how it was solved.

Which one is it? The following post saw this orientation problem, and
I see it as well. When I do a refine_mesh and write the output file
into either a mesh format or vtk, both do not render properly (some
tetrahedra have color problems).

Thanks,


On Sat, Jul 14, 2012 at 6:59 AM, Zohar 
<>
 wrote:
>
> Hi,
>
> Instead of posting a few threads I thought to group my questions into one
> thread.
> My first two questions please:
>
>         C3t3 c3t3;
>         tet_generation(srcPoly, c3t3); // Uses 3D mesh generation where 
> srcPoly is
> a polyhedron
>
>         // Triangulation 3
>         typedef C3t3::Triangulation Tr3;
>         typedef Tr3::Vertex_handle Vertex_handle;
>         Tr3& tr = c3t3.triangulation();
>
>         // Add points
>         ...
>         for ( int i = 0 ; i < nV ; i++ )
>                 tr.insert(GT::Point_3(V(0,i), V(1,i), V(2,i)));
>
>         // draw tr facets
>         vector<GT::Point_3> points;
>         vector<int> tris;
>         int vInd = 0;
>         for ( Tr3::Finite_cells_iterator cit = tr.finite_cells_begin()
>                 ; cit != tr.finite_cells_end() ; cit++ ) {
>                 for ( int ti = 0 ; ti < 4 ; ti++ ) {
>                         for ( int i = 0 ; i < 3 ; i++ ) {
>                                 
> points.push_back(cit->vertex((ti+i)%4)->point());
>                                 tris.push_back(vInd);
>                                 vInd++;
>                         }
>                 }
>         }
>         MObject omesh = cgal2mesh(points, tris); // draws the facets
>
>
> 1. I just arbitrarily iterated the facets of a cell. How do I iterated them
> such that they would have proper orientation (ccw)?
>
> 2. I'm working with the triangulation of the mesh generation. I understand
> it's Regular_triangulation_3. When I add the new points, I get intersections
> by very long faces, while I expected to get a clean delaunay triangulation.
> Does the regular triangulation behaves differently (or perhaps I misused the
> c3t3)? If it is, is there an easy way to convert it to delaunay?
> The mesh generation generates a fine triangulation, and adding the points by
> themselves also generates a fine triangulation. It is as if the two are
> colliding.
>
> Thanks
>
>
>
>
>
>
>
> --
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> Sent from the cgal-discuss mailing list archive at Nabble.com.
>
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