CGAL users discussion list

["Laurent Rineau (GeometryFactory)" <>]

Le mercredi 20 octobre 2010 16:39:30, Rolf Wester a écrit :
> Hi,
> 
> I'm totally new to CGAL and as CGAL is quite a big library I'm a little bit
> lost in the CGAL universe.
> 
> I would like to triangulate a half sphere and get the vertices and cells. I
> modified the triangulating a sphere example:
> 
> FT sphere_function (Point_3 p) {
>    const FT x2=p.x()*p.x(), y2=p.y()*p.y(), z2=p.z()*p.z();
>    if(z2 < 0.0) return 0.0; // added this line
>    return x2+y2+z2-1;
> }

z2 cannot be <0, because it is the square of a number. What is more, you must 
return a stritcly positive number for the outside of your object. I suggest:

  if(p.z() < 0) return 1.;

And the mesh methods in CGAL-3.7 are only for smooth objects. The mesh will 
not be very acurate around the big circle x^2+y^2=0, z=0.

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