> All that would be needed is a nurbs tesselater into the pipeline, i haven't looked
at
> the povray code but wouldn't this be how the bicubic patches are handled or is it
> directly rendering the bicubic surface (not tesselating it).

There is a bicubic type 2 option in the superpatch that pseudo-direct renders.  It's
faster than the other methods and uses just a little more memory than type 0.  My
understanding is that NURBS can be reduced to bicubic b-spline patches by inserting
knots to make them uniform.  I looked into doing this myself but the liturature I've
seen on nurbses is way too complex.  Perhaps the problem is trivial if one has the
right resources.

-Mike

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Cliff Bowman wrote:
> Would "Non-Uniform Rational B-Spline Thingys" have been much of an
> improvement?

Heh heh. How about just "Non-Uniform Thingys". Then we could all have
a lovely discussion about the benefits of modelling with NUTs. Or is
that: We nuts could all have a lovely discussion about the benefits
of modelling...

<gd&r>
Charles
-- 
http://www.enter.net/~cfusner
"...Then darkness took me, and I strayed out of thought and time,
 and I wandered far on roads that I will not tell..." 
                              -The Two Towers, JRR Tolkien

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TonyB wrote:
>  
> Sorry, I just want to clear up one thing. NURBS is not plural for NURB.
> NURBS is the acronym for Non-Uniform Rational B-Spline. The correct
> pluralization is NURBSs, no matter how ulgy it sounds.
> 

<;-)>
The plural of NURBS is NURBSes.  The distinction between singular and
plural is thereby audible, and it follows the established convention
followed in such words as "buses" and "gases".
</;-)>

Actually, the convention seems to be to expand NURBS to "Non-Uniform
Rational B-Splines", in which case NURBS is (are?) already plural.  In
Piegel & Tiller it's used as a plural.

-- 
Mark Gordon
mtg### [at] povrayorg

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On Fri, 27 Aug 1999 18:31:47 -0400, Charles <cfu### [at] enternet> wrote:

>Cliff Bowman wrote:
>> Would "Non-Uniform Rational B-Spline Thingys" have been much of an
>> improvement?
>
>Heh heh. How about just "Non-Uniform Thingys". Then we could all have
>a lovely discussion about the benefits of modelling with NUTs. Or is
>that: We nuts could all have a lovely discussion about the benefits
>of modelling...
>
You are Charles Danials and I claim my ten pounds.

In-joke for a completely different group, where he's a character. A
real one.

Anyway - what IS a "Rational B-Spline"? Will it debate the pros and
cons of various techniques to model a specific item, or is in fact not
able to converse rationally?

"Oh no, you don't wanna do that. Sure you can do it with a torus if
you tweak this and that, add a few blobs and cut way that bit over
there - but I'd recommend using B-Splines, I really would".


Cheers,

Cliff Bowman
Why not pay my 3D Dr Who site a visit at http://www.who3d.cwc.net/

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> Anyway - what IS a "Rational B-Spline"? Will it debate the pros and
> cons of various techniques to model a specific item, or is in fact not
> able to converse rationally?

I think it has something to do with weights.  Each point has a weight that
controls the shape of the spline.  If the weights of all the points is
increased the line will not change.*

-Mike

*Disclaimer - some or all of this may very well be completely wrong.

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Cliff Bowman wrote in message <37cac361.90304208@news.povray.org>...
>On Fri, 27 Aug 1999 18:31:47 -0400, Charles <cfu### [at] enternet> wrote:
>
>>Cliff Bowman wrote:
>>> Would "Non-Uniform Rational B-Spline Thingys" have been much of an
>>> improvement?
>Anyway - what IS a "Rational B-Spline"? Will it debate the pros and
>cons of various techniques to model a specific item, or is in fact not
>able to converse rationally?


Personally, I prefer my B-Splines to be irrational.

Mark

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Nieminen Juha wrote:
>  What are the advantages of NURBS (or should I say NURBSes?) over bicubic
>pathces?
>
>--
>main(i,_){for(_?--i,main(i+2,"FhhQHFIJD|FQTITFN]zRFHhhTBFHhhTBFysdB"[i]
>):5;i&&_>1;printf("%s",_-70?_&1?"[]":" ":(_=0,"\n")),_/=2);} /*- Warp -*/
>

I am not sure where this should be posted because this thread has taken a
number of turns.

NURBS have an advantage of being used in a number of good programs.
(Rhino3D)

If NURBS are to be added to POVRay I thank thay should be rendered directly
like the other primitives. Bicubic patches seem odd in that they are not
rendered directly.  They have a problem of showing gapes and holes because
of this. POVRay is strong because it uses objects based on math. NURBS can
be rendered directly and would produce very detailed results.


I am not sure how this will be taken but some objects like NURBS could be
external objects included like images and rendered. This could also be used
with other formats like 3DS and LWO.

#declareEXTOBJ MYLWO =  "My object.lwo";

#MYLWO{translate x*10}

For NURBS this could be done useing the openNURBS provided by Rhino3D

Sub-Parts could be accessed like properties in object oriented programming
or like the color components of a pigment used in a function.

#MY3DM.wheel.texture = MY_POV_TEXTURE;

Not sure how that would work but the idea should be simple.

As for which is better between SubDivision and NURBS I really think they
each have their uses. Sometimes it is hard to model with subdivision
somthing that NURBS does easy. It goes the other way also.

Am I way out for POVRay here?

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in news:web.3ffc330de3854bcb4e1f4eb10@news.povray.org m1j wrote:

> Am I way out for POVRay here?
> 

Kind off ..... you replied to a post that is some 3,5 years old :)


Ingo

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"ingo" <ing### [at] tagpovrayorg> wrote in message
news:Xns### [at] netplexaussieorg...

>
> Kind off ..... you replied to a post that is some 3,5 years old :)

Heh - that "Nieminen Juha wrote:" threw me for a minute....

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On 7 Jan 2004 12:21:53 -0500 ingo wrote:

>Kind off ..... you replied to a post that is some 3,5 years old :)

  Wow, I retrieved Warp's original (referenced) post and the thread
moved to the top of my displayed messages in this group ;)

-- 
Alan
ako### [at] povrayorg
a k o n g <at> p o v r a y <dot> o r g

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