Jurgens Shader

A filmic, realistic shader pack for Iris (Minecraft 1.21.1, NeoForge and Fabric), tuned for an RTX 4070 at 1440p and for Distant Horizons.

What you get

• Physically based sky: atmosphere tables computed on the GPU, a detailed sun disc with limb darkening, granulation and sunspots at low sun, a soft solar aureole, golden hours and sunsets that keep their colour.
• Volumetric clouds: a 3D Perlin-Worley cloud field with light marching, soft rims, dark stormy decks in the rain and cloud shadows on the ground.
• A rich night sky: a detailed procedural moon (maria, craters, ray systems, earthshine, eight phases), thousands of stars with colour and scintillation, a Milky Way with dust lanes and nebulae, zodiacal light, occasional aurora in cold biomes, shooting stars, comets and satellites.
• Water: calm waves, realistic absorption and scattering (biome-aware colour), screen-space reflections, caustics, foam, refraction, statistically correct reflections of distant lakes, swimming wakes and ripples.
• Light and shadow: soft PCSS shadows up to 192 blocks, coloured shadows through stained glass, coloured block light (voxel flood fill), screen-space ambient occlusion with multi-bounce, contact shadows, volumetric light with per-step cloud shadows.
• Eye and camera: automatic exposure with local exposure (exposure fusion), bloom, lens flare, a calm enchantment sheen, optional depth of field and motion blur, nine tonemappers (Uchimura GT by default).
• Dimensions: the Nether with biome atmospheres, the End with a black sun, nebulae, comets and void beams.
• Six profiles from POTATO (integrated graphics) to CINEMATIC; HIGH is the default.

Requirements

• Minecraft 1.21.1 with Iris 1.8.x (tested with Iris 1.8.14 on NeoForge 21.1 and Sodium 0.8.13).
• A GPU with OpenGL 4.3 compute shaders for the full feature set; without them the pack falls back to simpler sky and clouds.
• Distant Horizons 3.3 is supported but optional.

Install

Drop the ZIP into .minecraft/shaderpacks, select it in the Iris shader menu. The pack starts with the HIGH profile; use the profile button for weaker or stronger hardware.

Performance

Measured in the test world at 2560x1440 on an RTX 4070 (HIGH): about 90 FPS at night with the monitor off, 65-70 FPS by day with the monitor on. Your numbers will differ with mods, view distance and base size; the profiles MEDIUM and LOW cost far less.

Known limits

• Dripping-water particles in dark caves show as small dark squares (vanilla particles).
• The frame-rate difference between the two measurement conditions above is not fully explained yet.

Credits

Code by Raffman with Claude (Anthropic, Claude Code). Parts of the tonemapping are based on published work by MJP / Stephen Hill (ACES fit), Hajime Uchimura (GT tonemapper), Timothy Lottes, Troy Sobotka (AgX) and others; see THIRD_PARTY_NOTICES.txt in the ZIP. Clouds after Schneider & Vos (Horizon Zero Dawn, 2015), distant water after Bruneton, Neyret & Holzschuch (2010), local exposure after Wronski (2022) - all implementations our own.