Nathan Kopp wrote in message <35817EBF.B5331009@ltu.edu>...
>Johannes Hubert wrote:
>> But giving POV-Ray the ability to trace NURBS as primitives (probably
even
>> in CSGs???) would make it stand out among the competition even more than
it
>> already does. A great to-hope-for feature! Go for it!
>
>NURBS are nothing without a good modeler.  It would be fairly easy to
modify
>the current Bezier code to handle simple NURBS surfaces... or at least
>non-trimmed NURBS.  Trimmed NURBS are quite difficult, IMHO.  It all boils
down
>to tesselating the surface into an internal triangle representation.
>
>However, modelers can already do the tesselation easily.  I've been working
on
>a compact mesh syntax with Thomas Baier for 3DS-to-POV conversions that
would
>also work to greatly reduce the size of any triangle mesh POV file.


I agree that you would need a modeler. I wasn't thinking to program NURBS
without one (yuk!). I was more thinking along the lines, that the mesh-files
exported by modeleres like Rhino are often huge. Exporting a direct NURBS
description in some POV-Ray format where NURBS would be a primitive-type,
would cut down this size immensely.
Like you wrote: The modelers to the tesselation, and the result is often
huge. The idea is to keep the file-size small and let POV-Ray do the
tesselation.
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.

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