How is this done?!

[Rodéric]

A procedural texture don't need existing data to be generated.
Fragment shaders just combine textures, they don't generate textures.
(well at least up to 2.0)

Perlin noise is an example of texture generation.

 

[Remi]

We must have different cultural backgrounds about computing... Haven't the two main HW vendors shown a few demos of procedural texturing done in fragment programs? That's generating a texture, it's simply a "just-in-time" generation - bye bye to the bitmap, just compute the texture's pixel at the last moment, that is when computing the pixel's output color. I would call that "procedural texturing"...

 

[darkblu]

A procedural texture don't need existing data to be generated.
Fragment shaders just combine textures, they don't generate textures.
(well at least up to 2.0)

Perlin noise is an example of texture generation.

i believe people use the term procedural rather liberally. IIRC, the original meaning of 'procedural texture' is of a 'virtual' texture source (in the terms of the rasteriser) - a procedural texture is one for which there does not exist a (bitmap) source object, but texel data is generate at the time of texel fetch. with time and popularisation, though, the term procedural has deviated from the original meaning up to the point where for procedural is taken virtually everything which is not originally loaded from the resources/image of the application. i.e. a texture which does come from an ordinary texture source but which was not loaded from resources/images but has been pre-computed some time in advance to its use is usually considere procedural just as well.