noise functions in GLSL

Not implemented, will never be.

They're only implemented on the 3DLabs Wildcat Realizm, as I understand it.

[Edited by - Promit on November 11, 2005 1:43:15 PM]

If these are not implemented, atleast the compiler should produce an error saying functions not supported or something. What's the point in compiling without complaining and returning 0.0 ?

Compatibility?

It's in their release notes too:

http://download.nvidia.com/developer/Papers/2005/OpenGL_2.0/NVIDIA_OpenGL_2.0_Support.pdf

It would be nice if there was a standard way in GLSL to claim support for different subsets of functionality.

If the hardware doesn't support noise functions, the driver SHOULD fall back to a software renderer, and produce the correct results.

Unfortunately, Nvidia usually prefers performance over compatability, even if the well-performing result is simply wrong. I do not know what ATI's windows drivers do. Mac OS X 10.4.3 will fall back, and will render shaders with noise() corrrectly.

Quote:

Original post by Promit They're only implemented on the 3dfx Wildcat Realizm, as I understand it.

That'll be a 3DLabs Wildcat Realizm [wink]

IMO noise is something that shouldnt be supported in glsl
search the www.opengl.org glsl forum someone has written a noise lookup via a texture (runs reasonably fast)

Given that core clock speed is increasing faster than memory bandwidth using instructions to calculate noise is a better solution than performing a texture lookup.

Anyways, if you need a noise function then look up 'simplex noise'

Quote:

Original post by phantom Quote: Original post by Promit They're only implemented on the 3dfx Wildcat Realizm, as I understand it. That'll be a 3DLabs Wildcat Realizm [wink]

Um...yeah. My mistake.

I want to generate a noise texture on the GPU, so I can't do a texture look.

Quote:

Original post by phantom Given that core clock speed is increasing faster than memory bandwidth using instructions to calculate noise is a better solution than performing a texture lookup. Anyways, if you need a noise function then look up 'simplex noise'

true noise undoubtably will be quicker on the gpu but the problem is its (quite a lot) of added complexitity (in card + drivers) for something that ultimatly is only gonna be useful in a few senerios (similar to instancing)