[1.19.2] [Solved] How to apply a custom shader to all blocks in a specific chunk?

[SoLegendary]

I've been playing around with how chunk rendering works, and found how to conditionally render specific chunks with this code:

https://pastebin.com/5UzA0s1F

This code prevents the rendering of all chunks outside of a 30 block radius around a specific mob type. However, my end goal is to just apply a shader to show those chunks are out of range, rather than just not render them at all - something simple like painting them all black or changing it to monochrome. I believe I'd have to write a fragment shader (.fsh) for this which I've done before but only in isolation, playing around with this editor here: https://patriciogonzalezvivo.github.io/glslEditor/. I am assuming here that the shader I write can get an input of the original colour of each pixel which I can then modify.

Does Forge provide this compatibility and if so, how can I go about registering and applying the shader in code once it's been written?

Also, I don't think I'm going worry about rendering entities or block entities in these "dark" chunks so hopefully that simplifies this.

EDIT: nevermind, I found a solution that doesn't require shaders - since I just want to darken the chunks and not apply any complex effects, I realised I can just mixin ModelBlockRenderer and change the lightmap values.

Edited January 8, 2023 by SoLegendary