Lighting

A chunk renders black unless it carries light data. Chunks read from an Anvil world have it cached in their region files, but generated chunks have none. The LightingChunk supplier computes sky and block light for them:

InstanceContainer instance = instanceManager.createInstanceContainer();
instance.setChunkSupplier(LightingChunk::new);

Light is computed the first time a chunk is sent to a client, then again after block changes, batched behind a 100ms delay set by minestom.send-light-after-block-placement-delay.

Precomputing lighting

Lighting chunks up front can speed up the first player join:

List<CompletableFuture<Chunk>> chunks = new ArrayList<>();
ChunkRange.chunksInRange(0, 0, 32, (x, z) -> chunks.add(instance.loadChunk(x, z)));

CompletableFuture.allOf(chunks.toArray(CompletableFuture[]::new))
        .thenRun(() -> LightingChunk.relight(instance, instance.getChunks()));

relight can be called from any thread, and is also how you fix lighting after a batch or any other bulk edit.

Full bright

A dimension type with ambientLight set to 1.0F renders every block fully lit, no light computation needed:

RegistryKey<DimensionType> lobbyDimension = MinecraftServer.getDimensionTypeRegistry()
        .register("minestom:lobby", DimensionType.builder()
                .ambientLight(1.0F)
                .build());

InstanceContainer lobby = instanceManager.createInstanceContainer(lobbyDimension);

WARNING

ambientLight blends between normal lighting at 0.0F and fully lit at 1.0F. Anything higher, such as the 2.0F in older snippets, breaks rendering.