Iris Shaders

Iris supports shaders — effects that change the game's appearance: shadows, reflections on water, fog, colors depending on the time of day. It's what only OptiFine could do before: today Iris is the most widely used way to beautify your game.

Shaders are a client-side matter. Iris is installed by the player on their own computer and the server doesn't know about it; as an operator, you don't have to do anything with it. Players download the mod itself and a shader pack, which is placed in the game folder.

Iris on Fabric requires Sodium — without it, it won't start. Shaders are demanding, and without optimized rendering the game would be unplayable. Sodium takes care of the basics, Iris adds the effects.

Iris doesn't support everything OptiFine can do. Most shader packs today work with Iris without issues, but there are older ones that need special OptiFine features and don't work correctly. It's worth recommending current packs to players.

The practical consequence for a server: shaders only change how the player sees the game — they have no effect on server performance. Conversely, a player with a weaker computer won't turn on shaders even if they install them. When they ask why it doesn't work for them, the answer is almost always computer performance, not server settings.

1. Iris is a client-side mod — it belongs on the player's computer, not on the server.
2. Install Fabric Loader for your Minecraft version (on NeoForge, Iris has its own path, follow the instructions on the mod page).
3. Install Sodium — Iris requires it on Fabric. Without it, the mod won't start.
4. Download Iris from modrinth.com/mod/iris in the version for your game version and loader.
5. Put the .jar into the mods folder (on Windows %appdata%\.minecraft\mods).
6. Launch the game through a profile with Fabric and verify that the shader section (Shader Packs) is visible in the settings.
7. Download a shader pack (shader pack) — look for one that lists Iris support.
8. In the shader settings, open the shaders folder and put the extracted pack into it.
9. Select the pack in the list and confirm. The game will re-render — it takes a while for the shaders to compile.
10. Measure performance: there is usually a big difference between shaders off and on. On a weaker computer, choose a lighter pack or lower settings.
11. Weaker computer: start with a simpler pack (without shadows and reflections) so the game stays playable.

Shaders are the player's concern — the server doesn't need to deal with them. When a player asks why they aren't working for them, it's almost always their computer or an incompatible pack.
Iris on Fabric needs Sodium. Without it, it won't start, and the error message tends to be less specific than one would expect.
Not all shader packs are for Iris. Recommend current packs with stated Iris support to players, not old ones from the OptiFine era.
Shaders significantly reduce performance. On a weaker computer, a simpler pack is better than higher effect resolution.
The mod version and the pack version must match the game version. After updating the game, both need to be replaced.
If a player breaks their game with shaders, they should first disable them in the settings — that way they'll find out whether they are really causing the problem.