CGAL users discussion list

[Laurent Saboret <>]

Hi Vidya,

I was able to reproduce your problem with the with the first example of the 
"Planar Parameterization of Triangulated Surface Meshes" package: 
Simple_parameterization.cpp

The error occurs of course on line line 55 that reads the OFF file:
stream >> mesh;
You can get diagnostic messages by replacing this line by:
CGAL::scan_OFF(stream, mesh, true /* verbose */);

The problem is that CGAL Polyhedron_3 class expects faces to be oriented 
counterclockwise as seen from the outside of the polyhedron. See 
http://www.cgal.org/Manual/3.3/doc_html/cgal_manual/Polyhedron/Chapter_main.html#Section_12.2

The proper OFF file is:
OFF
8 10 0
-1.0 1.0 1.0
1.0 1.0 1.0
1.0 1.0 -1.0
-1.0 1.0 -1.0
-1.0 -1.0 1.0
1.0 -1.0 1.0
1.0 -1.0 -1.0
-1.0 -1.0 -1.0
3 5 6 1
3 2 1 6
3 0 3 4
3 7 4 3
3 6 5 7
3 4 7 5
3 1 0 5
3 4 5 0
3 2 6 3
3 7 3 6

Best regards,
--
Laurent Saboret
INRIA Sophia-Antipolis



 a écrit :
> Hi everyone,
>
> I am a new user of CGAL and I am trying to make use of the "Planar 
> Parameterization of Triangulated Surface Meshes" sub-package for my work. I am 
> trying to parameterize a simple cube described by the following OFF file:
> OFF
> 8 10 0
> -1.0 1.0 1.0
> 1.0 1.0 1.0
> 1.0 1.0 -1.0
> -1.0 1.0 -1.0
> -1.0 -1.0 1.0
> 1.0 -1.0 1.0
> 1.0 -1.0 -1.0
> -1.0 -1.0 -1.0
> 3 5 6 1
> 3 2 1 6
> 3 0 3 4
> 3 7 4 3
> 3 6 5 7
> 3 4 7 5
> 3 1 5 0
> 3 4 0 5
> 3 2 6 3
> 3 7 3 6
>
> However I get an error message "Cannot read OFF file". I am not sure where I 
> am going wrong out here. Is it possible to parameterize a cube with one face open ?
>
> Thanks, Vidya