CGAL users discussion list

["Sebastien Loriot (GeometryFactory)" <>]

listboss wrote:
> Thanks for your help Sebastien,
>
> > 1) in this line
> > 0.0 10.0.0 0.0
> > 10.0.0 is not a correct value
>
> This happened when I pasted the code to email. The file on my machine
> is alright.
>
> > 2)orientation of faces is not consistent.
>
> In CGAL, how do you make orientation of Polyhedron_3 consistent
> (assuming it is orientable) ?
I guess you need for any pair of facets sharing an edge that
the common edge is oriented in opposite way in each facet.
ex: I consider 4 points, with points 1 and 2 shared.
a correct orientation is:
0 1 2
3 2 1

You can also use this convention:
*for a close surface: facet seen from outside the object are 
counterclockwise oriented
*for an open surface: choose one "side" and facets counterclockwise.

Note that the Polyhedron demo of CGAL provide a plugin that try to 
reorient a triangle soup.
The plugin inside-outside inverse all orientation of facets.

S.

> > For the second problem reported, if you enable assert check in CGAL,
> > you would have get this error message:
>
> What is the test that I should be sending to CGAL_assertion() ?
I was not clear, the assertion is already in the CGAL code.
You probably compile CGAL in release mode where all
assertions are disable. If CGAL was compile in debug mode you would
have assertion enable.
See here:
http://www.cgal.org/Manual/latest/doc_html/installation_manual/Chapter_installation_manual.html#Subsection_4.7
how to build the lib in debug and release modes. Then setting correctly
CGAL_DIR will do the job.



> Thanks again