[vtkusers] Is it possible to have a "bounding sphere" for an actor

[Elvis Dowson]

Hi,
       I'm just going through the vtkBoundingBox class, to see if I  
can create a vtkBoundingSphere class based on this class.

I'm not clear as to what the min point and max point method parameters  
do for most of the methods in the vtkBoundingBox class.

If I were to adapt it for creating a bounding sphere, what would the  
correct replacements be, for these parameters, or should I still  
continue to use them?

Best regards,

Elvis Dowson