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dimensionX

noise functions in GLSL

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Promit    13246
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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dimensionX    100
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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Solias    564
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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RichardS    298
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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zedzeek    528
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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_the_phantom_    11250
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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Promit    13246
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.

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zedzeek    528
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)

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