Wasn't it Jeremiah Isaacs who wrote:
>Where is the center of the sphere after the transformations in <x,y,z>>coordinates?
Since it's spherically symmetrical, you can always ask POV where its
centre is.
#declare MySphere =
sphere {0,1
translate z*10
rotate SomeVector
}
#declare Centre = (max_extent(MySphere) + min_extent(MySphere))/2;
--
Mike Williams
Gentleman of Leisure