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Mappings

Default mappings​

  • Fabric (pre-26.x): Official Mojang mappings via Loom's officialMojangMappings()
  • Fabric (26.x+): No mappings needed. Minecraft is unobfuscated. Prism sets fabric.loom.disableObfuscation=true automatically.
  • NeoForge / Forge: Official mappings via ModDevGradle

Yarn mappings​

Fabric projects can use Yarn mappings instead of Mojang mappings:

fabric {
    loaderVersion = "0.18.6"
    yarn("1.21.1+build.3")
}

When yarn() is set, Prism uses net.fabricmc:yarn:{version}:v2 instead of officialMojangMappings(). Yarn is only available for obfuscated versions (pre-26.x).

Unobfuscated versions (26.x+)​

Starting from Minecraft 26.1 (1.21.11), the game ships with unobfuscated source. This means:

  • No intermediary mappings are used
  • No remapping is applied to mod JARs
  • Loom's officialMojangMappings() is not called (would throw an error)
  • Fabric dependencies use implementation instead of modImplementation (no remapping needed)
  • Access wideners still work (they widen access levels and mutability, not related to obfuscation)
  • Mixin refmaps use static remapping

Prism handles all of this automatically based on the Minecraft version. You do not need to configure anything differently for 26.x.

Parchment​

Parchment adds parameter names and Javadoc to Mojang mappings. Only applicable to obfuscated versions (pre-26.x).

version("1.21.1") {
    parchmentMinecraftVersion = "1.21.1"
    parchmentMappingsVersion = "2024.07.28"

    fabric {
        loaderVersion = "0.18.6"
    }
    neoforge {
        loaderVersion = "21.1.222"
    }
}

Both parchmentMinecraftVersion and parchmentMappingsVersion must be set. If only one is provided, Parchment is skipped with a warning.

Common project compilation​

The common subproject compiles against vanilla Minecraft. Prism resolves the correct artifact automatically:

Minecraft versionArtifactSource
1.20.2+NeoForm (net.neoforged:neoform)NeoForge Maven
1.20.1 and olderMCP (de.oceanlabs.mcp:mcp_config)NeoForge Maven

For older versions where NeoForm does not exist, Prism falls back to MCP and uses MDG Legacy in vanilla mode.

The resolved version is cached in ~/.gradle/caches/prism/ for 24 hours.

To override:

version("1.20.1") {
    neoFormVersion = "1.20.1-20230612.114412"
    // ...
}