[Sidefx-houdini-list] GLSL Function library
sidefx at trinix.ca
Mon Dec 14 23:00:38 EST 2009
I've continued my test.
First problem was the way I called the texture. I've figured out I need
a parameter of type "File - Image" and not just "File" because that
Second problem is how to generate the texture permTexture from the C
code provided. My knowledge is too limited here but I've found on the
web the permTexture.png that works well apart from an edge artifact.
I will put that aside for a while but eventually I'd be interested in
using SideFx functions but I still wonder how I can call
perlin_turbulence for example.
> The files in gpgpu are heavily macro'ed to overcome a lot of hardware
> limitations, and also so that they can run in Nvidia's Cg (Sony Cell
> workstation) and OpenGL's GLSL. Most are texture lookups in pixel
> coords, not UVs. You can consider code there to be like pseudocode,
> rather than GLSL (the framework around it is also built on the fly, like
> uniforms and other functions).
> All the noise functions in that directory require a source texture with
> random values in it, otherwise it won't be terribly noisy.
> And yeah, most implementations of GLSL's noise() function that I've seen
> return a rather un-noisy constant 0.
> The link Ed posted is a good quality noise method, though it still
> requires a source texture to operate (though it specifies that texture
> for you). You might be able to embed one in a SHOP asset, and reference
> it from an invisible texture map parameter on the node.
> François Duchesneau wrote:
>> I've manage to compile it and it gives a result. However it doesn't look
>> really like the noise.
>> From what I understand it uses a permutation texture and a lookup
>> texture but they don't provide it. I think I can figure it out from the
>> array of pseudo-random number in the C code. For now I'll concentrate to
>> better understand GLSL altogether but I'm pretty confident it'll work.
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