On Wed, Jan 27, 2010 at 9:35 AM, Tom Browder <[email protected]> wrote:
> Thanks for the input, Cliff.
>
> I'm really interested in the idea Sean mentioned some time ago that
> the nurbs primitive will aid the conversion process from CSG to BREP.
> Is or will there be a way to convert other CSG primitives to nurbs as
> an intermediate step?
A fair bit of the foundational logic of expressing CSG shapes in BREP
form is present - what we still need to do is
a) apply rotation and translation logic to the BREP expressions of CSG
shapes to "put them in place", so to speak
b) generate a "evaluated nurb" that is the result of boolean operations on
the BREP versions of the CSG primitives - that gives us an evaluated
NURBS version of a CSG model. (this is hard)
c) lots of robustness testing with all sorts of CSG
b) in particular will take some dedicated, focused time - there are some
thorny mathematical issues to work out when intersecting NURBS
surfaces. Without it, NURBS versions of CSG primitives are just slower
instances of the CSG primitives as far as raytracing is concerned. Once
we CAN do b), we can essentially convert CSG models to NURBS models,
and then techniques for doing things with NURBS will apply.
Cliff
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