IrisCaves — Alex's Caves × Shaders

Alex's Caves looks incredible without shaders and kind of falls apart with them. Its cave biomes lose their colored fog and glow, the primordial boss stops painting the sky red, and half its projectiles turn invisible. IrisCaves fixes that — it teaches your shader pack about Alex's Caves so the two finally play nice.

No pack editing, no "download this special version." Drop the mod in, keep the shader pack you already use, and IrisCaves quietly writes a patched copy next to it.

What it does

• Biome atmosphere. The six Alex's Caves cave biomes get their real fog color back under shaders — the toxic green, the primordial gold, the abyssal blue, and so on. Candy Cavity and Primordial Caves keep their sunlit look, and Forlorn Hollows gets properly oppressive.
• Abyssal Chasm, sealed off. The sky, sun, moon, clouds and sun rays are hidden in Abyssal Chasm, so it finally reads like the crushing deep instead of a cave with a sunny hole in the ceiling. World lighting is left alone, so the biome stays lit by its own glow rather than going pitch black.
• Luxtructosaurus. When the primordial boss is active, the sky and fog turn the same ominous red it uses in vanilla, overriding the normal cave color. Fully tunable (color + strength).
• Deepsight. The Deepsight effect actually brightens dark areas again, so you can see with it on.
• Invisible things, visible again. Sea Staff bolts, the Dreadbow's shadow arrows, the thrown Extinction Spear, totem/dinosaur spirits, ferrouslime gel, the Bubbled effect — all of these vanish under shaders normally. IrisCaves makes them show up.

Everything above ships with in-game sliders on Complementary (under Shader options → Lighting Settings → Alex's Caves Biome Lighting) and on Photon (its own Alex's Caves button on the main options screen, in English and Russian).

How it works

On launch, IrisCaves finds a supported pack in your shaderpacks/ folder and writes a patched copy called <pack>_iriscaves. Your original pack is never touched. Pick the _iriscaves version in the shader menu and you're done. It's a normal pack — no dependency on shader-loader internals, so it keeps working across Iris/Oculus updates. When you update the pack, the patched copy is rebuilt automatically.

Supported shaders

Works best on the Complementary family — Complementary Reimagined or Unbound together with Euphoria Patches — and on Photon. Both get the full feature set plus the settings GUI.

It also supports BSL, Bliss, Solas and Super Duper Vanilla with the most portable effects (biome cave-fog tint + the red boss atmosphere). Other packs are left untouched rather than broken. The biome and boss detection runs on the Java side, so it's accurate regardless of pack.

Note: the brightness tweaks (Forlorn Hollows darkness, Candy/Primordial sunlit look), the Abyssal Chasm sky cutoff and the settings sliders are Complementary- and Photon-only — they rely on lighting internals the other packs don't share. MakeUp-UltraFast isn't supported at all: it has no single cave-fog color to hook, so the mod leaves it alone instead of half-breaking it.

Config

config/iriscaves-client.toml:

• autoPatch — master switch. Set it to false and the mod won't scan your shaderpacks folder or generate anything.
• patchBlacklist — packs to never touch. Case-insensitive, matched by substring, so "photon" covers photon_v1.3b. There's an example in the file showing the format.

Requirements

Minecraft 1.20.1 — Forge, Oculus (Iris for Forge), Alex's Caves (+ Citadel)

Minecraft 1.21.1 — NeoForge, Iris (+ Sodium/Embeddium), Alex's Caves (+ Citadel)

You need a shader runtime either way — this is a shader companion. Client-side only, and safe to add or remove at any time.

FAQ

Do I need a special shader pack? No. Use any supported pack you already have — the mod makes the patched copy for you.

It made a second pack in my list. That's the point — <pack>_iriscaves is the patched one. Select it.

I don't want it patching one of my packs. Add its name to patchBlacklist in the config, or flip autoPatch off to disable patching entirely.

Some effect looks off on BSL/Bliss/Solas/Super Duper Vanilla. Those get the lightweight integration; you can fine-tune the colors in lib/misc/alexCavesBiomes.glsl inside the generated pack.