[grt-talk] Preliminary CSG in CVS

[Nikodemus Siivola]

OK, got CSG working: hacked the old non-unit-box to work with it as well,
but that's just temporary.

All object types must implement:

 * intersect-first => positive grt float

 * intersect-all => sorted vector of positive grt-floats, may be empty

 * normal

Solids must also implement:

 * inside: negative when point inside, zero at surface, positive outside
   (name will change: maybe halfspace better?)

Difference and intersection have been implemented, but the interface will
be improved (now only two arguments to each), and bounding will be added.
Union, merge, and invert also coming up. Currently the same pigment applies
to the whole CSG, but this will change: individual parts will get their own
surface properties.

Cheers,

  -- Nikodemus