ColorLight — GPU Lighting Mode

ColorLight's colored light is applied on the graphics card: a Sodium shader looks up the light for every pixel instead of baking colour into chunk vertices. The light is smoother, and chunks are not rebuilt when it changes.

Light propagation is still computed on the CPU (the Lua methods grid and smooth). Only the application of light to pixels has been moved to the GPU.

How it works

Light volume on the GPU. The light lives in a sparse volume around the camera, stored in two texel buffers (GpuLightVolume):

• data: a header (camera, flags, tint settings) and a list of sections, each holding a slot number or -1;
• pool: slots of 4096 cells (16 KiB each); only a section that holds light gets a slot. A cell stores the light colour 0x00BBGGRR and a "solid block" bit.

Sections are addressed in a ring, so the window follows the camera without moving any data. The shader window is 31 sections horizontally and 15 vertically. A light change rewrites only a few KiB of video memory.

Shader. A copy of Sodium's terrain shader (colored_terrain.vsh/.fsh) with a shared include, colorlight_data.glsl. For every pixel it:

1. determines the face normal from screen-space derivatives;
2. reads the light colour and level from the volume (with smooth interpolation);
3. builds the final colour: vanilla lighting in which the part added by block light is recoloured to the source's colour.

Sky light is left untouched, so the tint washes out by day and is fully visible at night. Fully emissive faces (glowing models) stay vanilla.

Sodium integration. Three small mixins (mixin/sodium):

Fallback. The GPU mode turns on only if all three mixins applied (they are skipped for unverified Sodium versions). If anything goes wrong, the mod switches back to the vertex-colour mode on its own and re-meshes. The GPU mode is not used with Iris shader packs.

Settings

Tint vividness (tint_gamma, 0–200%):

If the colour lasts too far or not far enough by default, change the line float retention = clamp(1.0 - tintGamma, 0.0, 1.0); in colored_terrain.fsh. The steepness of the whole slider is set by the * 3.0 factor in the exponent line.