In article <38C06E3A.9D90DCC4@pacbell.net>, lin### [at] povrayorg wrote:
>> if not, how hard would it be to add it?
>
>Techically it is possible. The question you need to ask is how useful
>would it be.

Sorry Ken, IMO that sounds like saying "why put in airbags when we already 
have seatbelts."

> NURBS are vary handy in modelling programs for defining
>and manipulating complex surfaces. Since POV-Ray is not a modelling
>program there will be no way for you to directly change a NURBS surface
>and it's usefulness becomes dubious.

I wouldn't use POV to change the surface just to render it.

> Triangles can and do accurately
>represent the surfaces that NURBS do. Most any capable program that
>can model NURBS surfaces can also exported to a format that can be
>converted to a triangle based mesh.

The program I use does convert the surface to triangles(and exports to POV 
with smooth triangles!) But, in the conversion there is always lost accuracy. 
When I render a converted mesh on the edges there is always straight lines 
connecting the vertices. This is my problem with it, I don't want to see the 
straight lines. Yeah, I could probably crank up the triangle count to minimize 
the error but, NURBS are perfectly accurate and I'd much rather get to 
construction data into POV so it can calculate the surface. Not to mention the 
extreme parse time you have to endure with thousands of triangles.

I checked out a program last night called Lightening3d. It exports NURBS to 
POV by converting to bezier patches. Sounds cool. Maybe this is the way that I 
could go?

Dave.
mic### [at] sympaticoca

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