[ODE] Subtractive Geometry

[GARY VANSICKLE]

> Dave Ratti wrote:
> > I'm still learning ODE, but have a quick question: I'd like to use
> > dCreateBox to create a box, and then some how put a hole through it: ie
> > put a cylinder through it and have the union of the two bodies be empty
> > space. Like the test_boxstack example, but instead of adding each
> > geometry, I'd like to subtract. Is this possible?
> 
> No, not currently.  There may be some wonderful hacks to
> this effect, but actually I don't think so.
> 
> --Adam

This brings to mind a question I've had for a while: do inertia tensors
subtract?  I figured out a way to add them long ago in a galaxy far far
away, but my patience ran out before I figured out how to subtract them.