libraries of 3D graphics primitives

[Raymond Yee]

	Does anyone know of a library of routines for drawing three
dimensional objects (spheres, cylinders, cylindrical loops, toruses
etc) in the public domain?  In other words, does anyone have 
a set of efficient, ready-to-plug-in routines, and general-purpose
routines that they would like to share? I've always wondered why the
graphics library (GL) does not supply such routines.  Are they too
user-specific to be of general use?

     Thanks in advance.

Raymond Yee
(raymond at cavebear.berkeley.edu)