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GPU/Procedural Texture Generation (edit)
Revision as of 23:36, 20 August 2015
, 23:36, 20 August 2015Hey, look what I found... (thanks @ yuriks for translating!)
The 3DS GPU supports procedural generation of texture data using [[GPU_Textures|texture unit 3]]. Little is known about this feature, albeit a few public hints have been dropped. The contents of this page are solely based on reports on a [http://www.4gamer.net/games/017/G001762/20120822007/ presentation] given by DMP.
== Overview ==
Procedural texture generation has four stages:
* Noise Module
* Repeat Module
* Base Shape
* F(g) and Lookup Table
== Noise Module ==
This stage applies noise on the input coordinates. Little is known about this other than that there are three noise parameters:
* Turbulence (?)
* Frequency
* Phase
== Repeat Module ==
This stage performs basic texture coordinate wrapping on the noised coordinates. It supports symmetric and mirrored wrapping. They don't seem to be configurable beyond that.
== Base Shape ==
The U’’ and V’’ coordinates are used to generate a scalar value in the range [0;1] from the wrapped coordinates using one of six functions:
* ADDSQRT2: sqrt(U’’*U’’+V’’*V’’) (?)
* U’’: U’’ (discards V’’)
* V’’: V’’ (discards U’’)
* MIN: min(U’’,V’’)
* MAX: min(U’’,V’’)
* ADD: U’’+V’’
The output of this function is named "g".
== F(g) and Lookup Table ==
F is a selectable function which transforms g to another scalar value. There are two known options for F:
* the identity function
* a triangle function
The final texel color is determined by using the value of F(g) as an index into a configurable lookup table.
== Overview ==
Procedural texture generation has four stages:
* Noise Module
* Repeat Module
* Base Shape
* F(g) and Lookup Table
== Noise Module ==
This stage applies noise on the input coordinates. Little is known about this other than that there are three noise parameters:
* Turbulence (?)
* Frequency
* Phase
== Repeat Module ==
This stage performs basic texture coordinate wrapping on the noised coordinates. It supports symmetric and mirrored wrapping. They don't seem to be configurable beyond that.
== Base Shape ==
The U’’ and V’’ coordinates are used to generate a scalar value in the range [0;1] from the wrapped coordinates using one of six functions:
* ADDSQRT2: sqrt(U’’*U’’+V’’*V’’) (?)
* U’’: U’’ (discards V’’)
* V’’: V’’ (discards U’’)
* MIN: min(U’’,V’’)
* MAX: min(U’’,V’’)
* ADD: U’’+V’’
The output of this function is named "g".
== F(g) and Lookup Table ==
F is a selectable function which transforms g to another scalar value. There are two known options for F:
* the identity function
* a triangle function
The final texel color is determined by using the value of F(g) as an index into a configurable lookup table.