CGAL users discussion list

[Samuel Hornus <>]

Hi,

I am using Min_sphere_of_spheres_d to compute bounding spheres at each
node of a hierarchy of points (a binary tree) :

   typedef CGAL::Cartesian_d<double>           K;
   typedef CGAL::Min_sphere_of_spheres_d_traits_d<K,double,3> Traits;
   typedef CGAL::Min_sphere_of_spheres_d<Traits> Min_sphere;

To speed-up the computation, I would like to reuse the
(already computed) Min_sphere from the left child of a node as a
starting point in which to include the points of the right child,
so as to obtain the bounding sphere of the node more quickly than from
scratch.

However, I get assertion failure in Min_sphere_of_spheres_d.h, line 253
(trunk), because vector 'l' is already non empty.

  template<class Traits>
  inline void Min_sphere_of_spheres_d<Traits>::update() {
    // set up the vector l containing pointers to the balls in S:
HERE -->    CGAL_MINIBALL_ASSERT(l.size() == 0);
    for (typename std::vector<Sphere>::const_iterator it = S.begin();
         it != S.end(); ++it)
      l.push_back(&(*it));
    
    // compute the miniball:
    update(Algorithm());
    is_up_to_date = true;
  }

Is it truly intentional in the sense that the computation is not
restartable ? Or is it a over-zealous assertion ?
The documentation doesn't seem to say anything about this, so I assumed
I can insert points. Query the radius, then continue to insert more
points... is this wrond ?

Thank you !

-- 
Samuel Hornus
http://www.loria.fr/~shornus/