Cornea Shaders

A Photon-inspired Iris shaderpack built to run fast on mid/low-end GPUs (target: RX 6500 XT, 1080p, 100–120 fps on the Ultra profile).

Made entirely with AI (Claude Opus 5.5 and Sonnet 5.5), steered and tested by one person. The code was written fresh and no Photon file is included, but Photon's source was read as a reference while building it, so the two share ideas and some structure. Photon is by SixthSurge and is the look this pack chases; Cornea is not affiliated with it. Details and the full chat log are on the website (the website branch).

Install

Click the green code button on the top right, then select download as a .zip file, or just download from the website. Then drop Cornea Shaders.zip into your instance's shaderpacks folder and pick it in Iris (Video Settings → Shader Packs). Requires Iris 1.7+ (tested to compile for Iris 1.11 / MC 26.x).

Features

• Physically based sky (Rayleigh/Mie/ozone) baked into a tiny LUT every frame
• Volumetric cumulus clouds (half-res + temporal accumulation) and cirrus
• Cloud shadows
• Soft shadows (PCSS-lite: 4-tap blocker search that skips filtering when nothing is in the way), coloured shadows through stained glass
• Coloured block lights via a voxel floodfill computed on the GPU
• Godrays (half-res volumetric light through height fog)
• Underwater godrays + animated caustics on the sea floor
• Water: wave normals, refraction, absorption, screen-space + sky reflections, sun glint
• SSAO (half-res), foliage subsurface scattering, waving plants
• TAA, single-pass bloom, auto exposure, ACES tonemap, sharpening
• Profiles: Low / Medium (default) / High / Ultra

Pipeline (8 screen passes + shadow)

Pass	What	Resolution
shadow / shadowcomp	shadow map, voxelization, light floodfill	2048² / 96³
prepare	sky LUT + light colours	193×108
deferred	SSAO	½
deferred1 / 2	clouds + temporal accumulation	½
deferred3	lighting, sky, fog	full
composite	godrays	½
composite1	water, translucents, underwater fog	full
composite2	TAA	full
composite3	bloom atlas + exposure	½
final	tonemap, grade	full

Development

• tools/gen_wrappers.py regenerates shaders/world*/ program wrappers.
• tools/check.py [glslang.exe] compile-checks every program in 4 settings permutations with glslang.
• tools/make_noise.py regenerates shaders/image/noise.png.

Status

Compiles cleanly for all programs and setting presets. Not yet tested in-game, so expect brightness and colour tuning to be needed.

License

All Rights Reserved (ARR). Copyright (c) 2026 Pavan Nemani. This project is not open source; see LICENSE for what you may and may not do.