UltraLow Shader

UltraLow Shader

A lightweight shader for Minecraft (Iris/OptiFine), built to add atmosphere without sacrificing performance. Great for modest hardware, or for anyone who wants a clean look without pushing their GPU.

Overworld
Sky color shifts with the time of day, darker and desaturated during rain
Twinkling stars at night
Soft light halo when looking toward the sun
Realistic directional lighting: blocks are lit by the sun during the day, by the moon at night, with a smooth transition at dusk/dawn
Directional lighting naturally fades out where there’s no skylight (caves, indoors) — no cast shadows, a clean look with no artifacts
Reflections on polished, smooth, metallic and glossy blocks: polished stone, quartz, obsidian, iron, gold, diamond, emerald, copper, glass, amethyst, redstone, sulfur, cinnabar…
Sun and moon reflections on reflective surfaces
Slightly glossy ground during rain
Water is more transparent, darker and desaturated at night for a more believable look
Underwater fog darkened at night
Chunk-border fog blends into the real sky color, with no visible edge
Bloom (glow) around torches, lanterns and other emissive blocks, active only at night
Lava rendered true to the original
Nether
Animated heat haze that builds up the further you look
Thick fog replaced with a simple render-distance fade for better visibility
Bloom always active on emissive blocks
Lava rendered true to the original
End

The End’s sky has been completely rebuilt:

A two-layer nebula slowly drifting in opposite directions, with dark dust and glowing wisps
Green and purple aurora curtains rippling near the horizon
Four layers of colored stars, denser along a Milky Way–like band
A deep, uniform sky below the horizon, free of artifacts
Chunk-border fog blends straight into that sky, matching the direction you’re looking
End blocks get a violet glow and atmosphere that match the sky’s color
Lighting stays stable and isn’t disrupted by the End’s random “End Flashes”
Radioactive End mode (experimental, toggleable)

A full alternate take on the End: a black-and-green sky with toxic stars, and real layered clouds — from clear air up high down to a dense, animated layer near the void, with a smooth gradient in between. Blocks take on a matching toxic green tint.

Customization

Every option can be tweaked from the shader menu, no file editing required:

Bloom: toggle, strength, radius
Nether vapor: toggle
Sun halo: toggle, strength
End nebula quality: light or detailed
End chunk fog blending into the sky: toggle
Radioactive End mode (experimental section)
Why “UltraLow”?

Every effect was designed to stay cheap to compute: no high-resolution shadow map, no ray marching, nearest-neighbor texture filtering to keep the pixel-art look intact. The costlier effects (bloom, vapor, halo) only run when it matters — at night, in the distance, when looking at the sun — and every one of them can be turned off individually for an even lighter footprint.