Packwright

Build data packs and resource packs at runtime with Fabric.

Packwright lets Fabric mods generate pack resources using plain Java builders instead of maintaining large collections of JSON files.

It supports assets and data including:

• Block and item models
• Blockstates
• Language files
• Loot tables
• Recipes
• Advancements
• Tags
• Predicates
• Item modifiers
• Enchantments
• Dialogs
• Entity variants
• World generation, including biomes, dimensions, features, carvers, material rules, structures, and noise settings

A content mod can generate nearly all of its resources directly from Java, leaving only its regular mod metadata and any resources it chooses to bundle normally.

Packwright is a heavily rewritten fork of ARRP — Advanced Runtime Resource Packs — originally created by HalfOf2/Devan-Kerman. It retains ARRP’s core concept, while replacing the builder API, codecs, registries, and world-generation support for modern Minecraft versions.

Adding Packwright

dependencies {
    modImplementation("net.vampirestudios:packwright:1.0.0+build.1-<minecraft-version>")
}

This dependency declaration works with both the Groovy and Kotlin Gradle DSLs.

Quick start

RuntimeResourcePack pack = RuntimeResourcePack.create("mymod:pack");

pack.addLootTable(
        Identifier.of("mymod", "blocks/ruby_ore"),
        LootTable.block()
                .pool(Pool.of()
                        .rolls(1)
                        .entry(Entry.item("mymod:ruby"))
                        .condition(Condition.survivesExplosion()))
);

PackwrightCallback.BEFORE_VANILLA.register(resources -> resources.add(pack));

Generated packs can also be dumped to disk as standard, ready-to-use data packs or resource packs.

See the dump() methods and the examples under src/test/java/test/. Complete custom-dimension examples are available in EmberWastesWorldgen and SkyIslandsWorldgen, alongside examples for other resource types.

Configuration

Packwright creates config/packwright.properties on first launch.

Every setting can also be overridden for an individual run using:

-Dpackwright.<key>=<value>

Key	Default	Description
threads	Half of the available processor cores	Worker threads used for resource generation
dump_on_close	false	Dump a pack’s contents when it is closed
dump_directory	packwright.debug	Directory used for generated pack dumps
debug_performance	false	Log lock-wait and performance information
pretty_json	true	Pretty-print generated JSON

FAQ

Is Packwright compatible with regular resource packs?

Yes. Packwright injects generated packs through Minecraft’s normal pack system.

Generated packs are placed directly above Minecraft’s built-in resources, allowing them to override vanilla assets. Resource packs supplied by other mods or selected by the player can still override Packwright-generated assets when they have a higher priority.

How do I migrate from ARRP?

Start by making the following replacements:

• net.vampirestudios.arrp or net.devtech.arrp → net.vampirestudios.packwright
• RRPCallback → PackwrightCallback
• rrp:pregen entrypoint → packwright:pregen

Existing rrp.properties and arrp.properties configuration files are migrated automatically.

Because Packwright substantially rewrites ARRP’s builder APIs, some generated-resource code may require additional changes. See the changelog and migration documentation for the complete list.