CGAL users discussion list

["Sebastien Loriot (GeometryFactory)" <>]

mahdavi wrote:
> hi all
> I use alpha complex ,my program is used regular triangulation  for  weighted
> points and I  want to  grow points  by constant alpha(a). please anybody say
> me that in weighted alpha  complex must be used alpha or square alpha ,
> //////////////////////////////////////////////////////////////////////
> Which is instruction correct?
> 1:Alpha_shape_3  as(P1.begin(), P1.end(), a, Alpha_shape_3::GENERAL);
> 2:Alpha_shape_3  as(P1.begin(), P1.end(), a^2 ,Alpha_shape_3::GENERAL);
> thanks.
In the case of weighted points, building the alpha-complex is equivalent 
to building the 0-complex of the weighted points with weights increased 
by alpha (w_i + alpha). If you want a weighted point to represent a 
circle (or a sphere), the corresponding weight is its squared radius.

S.