[ODE] Regarding CSG

[Peter]

For whoever asked this a couple of days ago, CSG is Constructive Solid
Geometry.  Theres really two operations in CSG, addition and subtraction,
adding objects together to create volume, or subtracting one object from
another to remove volume.  Addition is supported natively in ODE via
clumping multiple geoms together via the use of GeomTransforms, so you could
make the ODE docs example of a table with 4 legs by creating 5
geomTransforms, 5 boxes, and positioning them all on one body.

As far as CSG subtraction goes, well, it's not supported natively, but you
could probably create "negative" geoms that remove contacts that fall within
them, so say you wanted to use a sphere to cut a hole in a box - if the
contact falls within the sphere, cancel the contact.  No idea if it'd work
and you're probably better off with using meshes and doing mesh based csg
externally of ode.

Just wanted to chime in with the geom stuff though.