CGAL users discussion list

["Laurent Rineau (CGAL/GeometryFactory)" <>]

Le vendredi 01 février 2013 13:47:01 Sidnei Basei a écrit :
> Hi all,
> 
> I'm trying to reconstruct a 3d model from x,y,z cloud points. I used CGAL
> Alpha Shape 3 with Delaunay triangulation to reconstruct it.
> 
> However, when I draw all triangles in OpenGL, I can see many holes (see
> attached image).
> 
> I tried with many alpha options and these holes are still visibles.

The issue is that the facets of the triangulation are not oriented. In 
OpenGL, 
you should draw using:
  glLightModeli(GL_LIGHT_MODEL_TWO_SIDE, GL_TRUE);

so that the lightning model of OpenGL draws both front and back faces of 
triangles, ignoring the orientation.

Or orient the facets towards the camera.

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