CGAL users discussion list

[Rasmus Bach Nielsen <>]

 You are of coures right. I was fiddling with the radius of the 
bounding sphere, instead of the radius of the sphere to mesh... Thank 
you for helping me see the obvious :-)

Regards
  Rasmus


On 21-10-2010 09:00, Sebastien Loriot (GeometryFactory) wrote:
> rusmus wrote:
> > Hello all,
> >
> >   I am new to CGAL, and I have a question regarding coordinates in
> > Mesh_complex_3_in_triangulation_3, using an implicit domain.
> >
> > Using the following code, I am able to mesh a sphere (I know that 
> > this goes
> > well, because the medit output looks right), iterate over the cells 
> > in the
> > mesh, and print the coordinates of the circumcenter of each cell. My 
> > problem
> > is with the interpretation of the coordinates. They are all between 0 
> > and 1,
>
> as explained in the documentation,
> http://www.cgal.org/Manual/latest/doc_html/cgal_manual/Mesh_3_ref/Class_Implicit_mesh_domain_3.html#Cross_link_anchor_1473 
>
> this is the function which indicates the signed distance from a point 
> to the surface. In you case you indicated that the sphere as radius 1.
> Don't forget to increase the square radius of the bounding sphere.
>
> S.
>
> > which would be OK if I could find some documentation that explained 
> > why, but
> > no such luck. I assume that they are somehow normalized, but how? and is
> > there a way of getting non-normalized coordinates?
> >
> >
> > #include <CGAL/Exact_predicates_inexact_constructions_kernel.h>
> >
> > #include <CGAL/Mesh_triangulation_3.h>
> >
> > #include <CGAL/Mesh_complex_3_in_triangulation_3.h>
> > #include <CGAL/Mesh_criteria_3.h>
> >
> > #include <CGAL/Implicit_mesh_domain_3.h>
> > #include <CGAL/make_mesh_3.h>
> >
> > typedef CGAL::Exact_predicates_inexact_constructions_kernel Kernel;
> > typedef Kernel::FT FT;
> >
> > typedef Kernel::Point_3 Point;
> > typedef Kernel::Vector_3 Vector;
> >
> > typedef FT (Function)(const Point&);
> > typedef CGAL::Implicit_mesh_domain_3<Function, Kernel> Domain;
> >
> > typedef CGAL::Mesh_triangulation_3<Domain>::type Triangulation;
> > typedef CGAL::Mesh_complex_3_in_triangulation_3<Triangulation> C3t3;
> >
> > typedef CGAL::Mesh_criteria_3<Triangulation> Criteria;
> >
> > using namespace CGAL::parameters;
> >
> > FT sphere_function(const Point& p)
> > {
> >     return CGAL::squared_distance(p, Point(CGAL::ORIGIN)) -1;
> > }
> >
> > Domain domain(sphere_function, Kernel::Sphere_3(CGAL::ORIGIN, 10.));
> >
> > Criteria criteria(facet_angle=30, facet_size=0.1, facet_distance=0.025,
> >                          cell_radius_edge=2, cell_size=0.1);
> >
> > C3t3 c3t3;
> >
> > int main(int argc, char* argv[])
> > {
> >     c3t3 = CGAL::make_mesh_3<C3t3>(domain, criteria);
> >
> >     for(C3t3::Cell_iterator it = c3t3.cells_begin();
> >     !it.is_end();
> >     it++)
> >     {
> >         C3t3::Cell_handle c = it;
> >
> >         Point p = c->circumcenter();
> >
> >         std::cout << p << std::endl;
> >     }
> >
> >
> > }
> >
> >
> >
> > I hope you can help me.
> >
> > Thank you in advance
> >   Rasmus Bach Nielsen