Firmament

A cleaner shader core and a faster sky, with the same look.

Changed

• Under the hood: shared shader code is reorganized, with named materials and one implementation of each lighting helper. Every other pass costs the same as in 0.2.0.

Performance

• Sky: the atmosphere pass computes the sun and moon once per frame instead of once per pixel and is about 1.3× faster by day and night.
• Fog and light shafts: 1.06–1.17× faster above and below water.
• Night sky: stars and clouds over open sky about 1.06× faster; ambient occlusion reconstruction about 1.03×.
• The figures are isolated GPU pass timings measured against 0.2.0 on an RTX 4060 Laptop GPU at 2560 × 1440 with the High preset, not frame rates. In-game FPS depends on the scene, render distance and hardware.

Compatibility

• The same 29 Minecraft Java versions as 0.2.0: 1.18.2; 1.19, 1.19.1, 1.19.2 and 1.19.4; 1.20–1.20.6; 1.21–1.21.11; 26.1, 26.1.1, 26.1.2, 26.2 and 26.3.
• Use the Iris and Sodium builds matching your Minecraft version; 26.2 and 26.3 target the OpenGL renderer. Recorded gameplay evidence remains 1.21.1 / NeoForge 21.1.228 / Iris 1.8.12 / Sodium 0.6.13 with 0.1.0-alpha.2.

Known issues

• After reloading chunks with F3+A, shadows of blocks outside your view appear once you look at them: Iris only builds chunks the camera sees.

Notes

• Rendering, presets and options are unchanged from 0.2.0; automated OpenGL comparisons match it within the project's equivalence limits.
• Keep the ZIP intact, place it in shaderpacks, select Firmament in Iris, start with High and adjust the preset for your setup.