"One of the many problems with shader code is that HLSL doesn’t support arrays in a meaningful way. Pointer math (and thus array indexing) just isn’t a thing on the GPU, so writing to a non-constant index of an array is impossible. To work around this, there are several places in the code with patterns like this:"

This is weird, AFAIK pixel shaders have had arrays since DX10 and the OpenGL equivalent through Buffers (and also Unordered Access Views for reading/writing pixel data) https://docs.microsoft.com/en-us/windows/win32/direct3dhlsl/...

Are VRChat shaders stuck to Direct3D9/ps_3_0 level functionality?