What FastPBR works with.
| Platform | Java Edition |
|---|---|
| Loaders | Iris |
| Minecraft versions | 1.18.2, 1.19.4, 1.20.1, 1.20.6, 1.21, 1.21.4 |
FastPBR is a lightweight shader pack for Minecraft Java built for the Iris pipeline. It leans on physically based atmospheric rendering to drive real-time skies, dynamic shadows, and volumetric fog, aiming for a visual jump past vanilla without the frame cost of a full path-traced pack. The project's confirmed builds top out at Minecraft 1.21.4, with no listed support yet for the current 26.x game versions.
Installing FastPBR with Iris
FastPBR needs Iris 1.6.0 or newer. RRe36 has said OptiFine is not supported and will not be added until it matches Iris' feature set, so confirm your loader before downloading.
- 1.Install Fabric, Quilt, or NeoForge with Iris for your target Minecraft version.
- 2.Download the FastPBR zip from its Modrinth page. Do not unzip it.
- 3.Open Video Settings, go to Shader Packs, and use Open Shader Pack Folder to reveal the shaderpacks directory.
- 4.Drop the zip into that folder, then select FastPBR from the in-game shader list.
PBR atmospherics without the path-traced cost
The PBR in the name refers to physically based rendering of the sky, sun, and atmosphere, not to material normal or specular maps. FastPBR will not add bump-mapped block textures the way a PBR-labeled resource pack would; RRe36 calls that mix-up a common misconception in the shaderpack community. What it does deliver is a mostly single-pass lighting model tuned to look good on hardware that would struggle with a heavier pack.
- Dynamic soft shadows
- Optional screen-space indirect lighting (HBIL)
- Temporal anti-aliasing and upscaling (TAAU)
- Procedural sky with volumetric clouds and fog
- Optional lens effects: depth of field, lens flares, vignette
- Distant Horizons compatibility since version 2.0
Performance and who it's for
Modrinth files FastPBR under its own low performance-impact tier, and RRe36 positions it as the fast alternative to heavier atmospheric packs like Rethinking Voxels. It still needs a graphics card with OpenGL 4.3 or newer. The creator lists Windows and Linux as supported platforms; macOS is not mentioned in the stated requirements.
Compatibility and known limits
FastPBR is client-side only, so there is nothing to install on a server. It picks up Distant Horizons support from version 2.0 onward, though the source does not document behavior alongside other visual mods.
- OptiFine is not supported and has no planned support
- Requires a GPU with OpenGL 4.3 or newer, on Windows or Linux
- Confirmed builds stop at Minecraft 1.21.4 as of the last Modrinth update, February 28, 2025
- Distant Horizons support starts at FastPBR v2.0
Watch FastPBR in Minecraft
FastPBR release showcase by RRe36
Questions about FastPBR.
5 questions
How do I install FastPBR?
Install Iris 1.6.0 or newer for your Minecraft version through Fabric, Quilt, or NeoForge, then download the FastPBR zip from Modrinth without unzipping it. Open Video Settings, go to Shader Packs, and use Open Shader Pack Folder to find your shaderpacks directory. Drop the zip in there and select FastPBR from the in-game shader list.
Does FastPBR work with OptiFine?
No. RRe36 has said OptiFine is not supported and will not be until it matches Iris' more advanced shader feature set. FastPBR only runs on the Iris shader loader, so confirm you have Iris installed rather than OptiFine before downloading.
Is FastPBR good for low-end PCs?
Modrinth lists FastPBR under its low performance-impact tier, and it is built to be a fast alternative to heavier path-traced shader packs. It still needs a GPU with OpenGL 4.3 or newer, so very old integrated graphics may still struggle even though the pack is lighter than most realistic shaders.
Which Minecraft version does FastPBR support?
FastPBR's confirmed builds cover Minecraft 1.18.2 through 1.21.4 on the Iris loader. The project was last updated on February 28, 2025, so there is no confirmed build for the current 26.x game versions. Check the Modrinth page before installing on a newer version.
Does FastPBR support Distant Horizons?
Yes, starting with FastPBR version 2.0. Earlier v1.x builds do not list Distant Horizons compatibility, so players running an older FastPBR version alongside Distant Horizons should update first.
