Add preprocessor for ShaderLab compiler - Githubissues

galacean / engine

A typescript interactive engine, support 2D, 3D, animation, physics, built on WebGL and glTF.

https://galacean.antgroup.com/

MIT License

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Add preprocessor for ShaderLab compiler #2059

Open Sway007 opened 3 months ago

Sway007 commented 3 months ago

The precessor should be capable of the following task:

[ ] support #include and #define macro expansion
take the function-like macro expansion into account:
```
#define saturate( a ) clamp( a, 0.0, 1.0 )
```
edge cases and issues processing should be coherent with the glsl 100 specification
[ ] can interpret the expression of branch macro, e,g. #if, ifdef, ifndef, else, elif, endif
```
#if defined(XXX) && YYY > 1.0 || ZZZ == 2
 ......
#elif ...
......
#endif
```
[ ] extract macros which have impact on the generated code (for engine use)

not necessarily implemented in preprocessor, maybe can be done with another more light way