surface interpolation?

[Rui Maciel]

Does OpenGL offer a way to, given a set of control points, to automatically
generate interpolated surfaces that pass through the control points? I've managed
to discover the glMap2() and glEval2() functions but, according to my test code, it
appears that the surfaces generated through this method don't cross the
intermediate control points.

So, does OpenGL offer a way to do this or do I need to hand-code it?

Thanks in advance,
Rui Maciel

[Wolfgang Draxinger]

Rui Maciel wrote:

> Does OpenGL offer a way to, given a set of control points, to
> automatically generate interpolated surfaces that pass through the control
> points? I've managed to discover the glMap2() and glEval2() functions but,
> according to my test code, it appears that the surfaces generated through
> this method don't cross the intermediate control points.

Those are the bezier evaluators, so there are points where are intercepted,
and points controlling the tangent direction.

Be aware that OpenGL evaluators have been implemented as part of the drivers
for most contemporary GPUs, so there's probably no gain using it instead of
implementing it in the own code.

> So, does OpenGL offer a way to do this or do I need to hand-code it?

Do it yourself. In the end it's easier and more flexible. Any textbook on
numerics should have an exhaustive chapter on interpolation and how to do it
efficiently.

This is better discussed on c.g.algorithms though, redirecting there.

Wolfgang
--
OpenGL tip #42:
How to exactly map texture texels to screen pixels:
<http://preview.tinyurl.com/cgndc8>

[**Group User**]

Dear Sir, I have a question in comp.lang.php and really need your help

Interpolation is expensive Sir,
OpenGL is actually not a perfect solution to graphics Sir,
Those that work better would definitely cost money Sir

I used to have some interviews about grphics Sir, and I was not in a
least perturb in making any attempt to resolve it Sir
1. I likely asked for a very high salary Sir
2. I don;t have a good tongue Sir
3. I am confident to self-claim that I do have a broader and bigger
brain
Thanks to everyone who used to be my professors (although I was forced
to obey rigorous rules), but I sometimes think of my past as a
glorious victory over painful ignorance. What if I was smart from the
start ? Will I be able to learn anything beautiful ?

Last but never least Thanks to Gods/Godesses, I am alive! Sir