World

World view

A WorldView is one dimension. Use the view that a callback (event, action, tick) receives only during that call.

Area	Methods
Basics	dimension(), isClientSide(), gameTime(), players()
Blocks	blockAt(pos), setBlock(pos, block), stateAt(pos), setProperty(pos, property, value), blockEntityAt(pos), emittedLight(pos)
Entities	spawnEntity(type, x, y, z), entitiesNear(x, y, z, radius)
Effects	playSound(pos, sound, volume, pitch), spawnParticles(particle, x, y, z, count, spread)
Game rules	gameRule(key), setGameRule(key, value)
Storage	storage(id), storage(id, options)
Scheduling	schedule(ticks, task)
Chunks and biomes	setChunkForced(x, z, forced), isChunkLoaded(x, z), biomeAt(pos), naturalSpawns(pos, category)
Dimensions	otherDimension(id)
Tags	tags(), isBlockIn(pos, tag) (Tags)

world.setBlock(pos, ResourceId.minecraft("stone"));
world.spawnEntity(ResourceId.minecraft("pig"), x, y, z);
Optional<WorldView> pocket = world.otherDimension(ResourceId.of("my_mod", "pocket"));

Create a BlockPos with BlockPos.of(x, y, z) and move it with offset, above, and below.

World storage

mod.events().register(WorldEvents.READY, world -> {
    StoredData stats = world.storage(ResourceId.of("my_mod", "stats"));   // per dimension, saved with the world
    stats.data().putInt("loads", stats.data().getInt("loads", 0) + 1);
    stats.markChanged();
});

• Each dimension has its own storage, and it is saved with the world.
• Call markChanged() after you change it.
• Versions, migrations, and client sync options are in Stored data and versions and Networking and sync.

DataTree

StoredData.data(), block entity data, and entity data are all a DataTree.

Method	Meaning
getInt/putInt, getLong/putLong, getDouble/putDouble, getBoolean/putBoolean, getString/putString	Read a value (you give a default) and write a value. put… can be chained
getBytes/putBytes	Byte array
child(key), findChild(key)	Subtree (creates it if missing / returns an Optional)
has, remove, keys, clear, copy	Key management

Scheduling tasks

world.schedule(20, () -> world.setBlock(pos, ResourceId.minecraft("stone")));   // after 20 ticks, on the server thread
world.schedule(20, () -> world.playSound(pos, ResourceId.minecraft("block.note_block.bell"), 1, 1));

• Scheduled tasks disappear when the server stops. They are not saved.
• If a scheduled task throws an exception, Poly Mod Loader logs POLY-SCHEDULE-001 and keeps running the next tasks.

Force-loading chunks

world.setChunkForced(chunkX, chunkZ, true);    // same as /forceload, saved with the world
world.isChunkLoaded(chunkX, chunkZ);
world.biomeAt(pos);
mod.events().register(WorldEvents.CHUNK_LOADED, (w, chunkX, chunkZ) -> { /* … */ });   // CHUNK_UNLOADED exists too

World events

On the server, each dimension goes through LOADED → READY → SAVING (on every save) → UNLOADED per server start. LOADED, SAVING, and UNLOADED share one listener type, WorldListener (world -> …).

mod.events().register(WorldEvents.LOADED, world -> { /* every dimension exists, before the first tick */ });
mod.events().register(WorldEvents.SAVING, world -> { /* changes made now are saved with the world */ });
mod.events().register(WorldEvents.UNLOADED, world -> { /* the last moment to read it while stopping */ });

• SAVING fires before autosaves, /save-all, and the save while stopping, before chunks and level data are written.
• Changes made in UNLOADED are not saved any more.

Timings, CHUNK_LOADED, CHUNK_UNLOADED, and the other events are listed in Events.