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noise functions in GLSL

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What is the word on GLSL noise1/2/3 functions on NVIDIA hardware (7800GTX, 81.85) ? Seems, these functions always return 0.0. Did anyone see the same result ?

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

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

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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 ?

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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.

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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.

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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)

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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'

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