This pack is a modification of the PSX shaderpack (https://github.com/ckosmic/minecraft-psx), which is a shader pack which emulates PlayStation 1 style graphics in Minecraft. The shader is intended for use with the MCSX modpack, a PlayStation 1 style horror modpack, however the shader should be compatibile with ~1.17 to 1.20 Minecarft through either Optifine or Iris, though compatibility is not guaranteed outside of the modpack.
The source code for this shader is available through this link https://github.com/ninjamike1211/PSX_MCSX/tree/main.
The biggest change this pack implements is floodfill colored lighting, but it also features changes to cave fog, changes to sky and fog rendering, multiple fog pass for translucents, and various other improvements and tweaks for mod compatibility.