> And then again (and here my math-incompetence shines through :-) - why
> tesselate at all? Couldn't POV-Ray use the direct mathematical functions for
> intersection tests?
> As I understand it, spheres for example are not tesselated internally, but
> instead intersected directly. Would something like this be possible for
> NURBS too?
> 
> Johannes.

Possibly. Not knowing much about NURBS mathematically, I couldn't say
for sure, but doing this tends to be computationally prohibitive - you
can tesselate enough that you can't tell the difference and still be a
hell of alot faster than direct intersection tests, in many cases. This
is presumably why POV uses a tesselated form for the current bezier
patches.

Michael Smith

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