I'm trying to check the blocks of nearby chunks in the spawn predicate of a mob I'm making. Currently, the predicate looks something like this:

 public static boolean checkMyMobSpawnRules(EntityType<? extends MyMob> entityType, ServerLevelAccessor serverLevelAccessor, MobSpawnType mobSpawnType, BlockPos blockPos, Random random) {
   ServerLevel level = serverLevelAccessor.getLevel();
   LevelChunk chunkAtPos = level.getChunkAt(blockPos);
   List<Block> blocks = chunkAtPos.getBlockEntities().values().stream().map(entity -> entity.getBlockState().getBlock()).toList();
   // Do stuff with blocks
 }

When I debug this code, I I noticed that chunkAtPos.getBlockEntities() returns a List with size 0. Since my predicate involves checking nearby blocks, this causes my predicate to always return false. Is there a better way to get the blocks in a chunk?

It's in a subclass of Monster. I pass a reference to this method to SpawnPlacements.register, which gets called in an event subscriber like the following:

@Mod.EventBusSubscriber(modid = Main.MOD_ID, bus = Bus.MOD)
public class ModEvents {
    private ModEvents() {
    }

    @SubscribeEvent
    public static void commonSetup(FMLCommonSetupEvent event) {
        event.enqueueWork(() -> SpawnPlacements.register(ModEntities.MY_MOB.get(), SpawnPlacements.Type.ON_GROUND, Heightmap.Types.WORLD_SURFACE, MyMob::checkMyMobSpawnRules));
    }
}

 

I figure I may as well give the whole spawn predicate:

public static boolean checkMyMobSpawnRules(EntityType<? extends MyMob> entityType, ServerLevelAccessor serverLevelAccessor, MobSpawnType mobSpawnType, BlockPos blockPos, Random random) {
        ServerLevel level = serverLevelAccessor.getLevel();
        LevelChunk chunkAtPos = level.getChunkAt(blockPos);

	// check 5x5 grid of chunks for crops, centered at chunkAtPos
        boolean nearbyChunkHasCrop = Stream.of(
                Utils.getBlocksFromChunk(chunkAtPos),
                Utils.getBlocksFromChunk(level.getChunkAt(blockPos.east(16))),
                Utils.getBlocksFromChunk(level.getChunkAt(blockPos.west(16))),
                Utils.getBlocksFromChunk(level.getChunkAt(blockPos.north(16))),
                Utils.getBlocksFromChunk(level.getChunkAt(blockPos.south(16))),
                Utils.getBlocksFromChunk(level.getChunkAt(blockPos.east(16).north(16))),
                Utils.getBlocksFromChunk(level.getChunkAt(blockPos.east(16).south(16))),
                Utils.getBlocksFromChunk(level.getChunkAt(blockPos.west(16).north(16))),
                Utils.getBlocksFromChunk(level.getChunkAt(blockPos.west(16).south(16))),
                Utils.getBlocksFromChunk(level.getChunkAt(blockPos.north(32))),
                Utils.getBlocksFromChunk(level.getChunkAt(blockPos.north(32).east(16))),
                Utils.getBlocksFromChunk(level.getChunkAt(blockPos.north(32).east(32))),
                Utils.getBlocksFromChunk(level.getChunkAt(blockPos.north(32).west(16))),
                Utils.getBlocksFromChunk(level.getChunkAt(blockPos.north(32).west(32))),
                Utils.getBlocksFromChunk(level.getChunkAt(blockPos.south(32))),
                Utils.getBlocksFromChunk(level.getChunkAt(blockPos.south(32).east(16))),
                Utils.getBlocksFromChunk(level.getChunkAt(blockPos.south(32).east(32))),
                Utils.getBlocksFromChunk(level.getChunkAt(blockPos.south(32).west(16))),
                Utils.getBlocksFromChunk(level.getChunkAt(blockPos.south(32).west(32))),
                Utils.getBlocksFromChunk(level.getChunkAt(blockPos.east(32))),
                Utils.getBlocksFromChunk(level.getChunkAt(blockPos.east(32).north(16))),
                Utils.getBlocksFromChunk(level.getChunkAt(blockPos.east(32).south(16))),
                Utils.getBlocksFromChunk(level.getChunkAt(blockPos.west(32))),
                Utils.getBlocksFromChunk(level.getChunkAt(blockPos.west(32).north(16))),
                Utils.getBlocksFromChunk(level.getChunkAt(blockPos.west(32).south(16)))
        ).flatMap(stream -> stream).anyMatch(block -> block instanceof CropBlock);

        boolean notUndergroundOrIndoors = true;
        for (int y = blockPos.getY() + 1; y < 320; ++y) {
            BlockEntity blockEntity = chunkAtPos.getBlockEntity(new BlockPos(blockPos.getX(), y, blockPos.getZ()));
            if (blockEntity != null) {
                Block block = blockEntity.getBlockState().getBlock();
                if (!(block instanceof AirBlock || block instanceof LeavesBlock)) {
                    notUndergroundOrIndoors = false;
                    break;
                }
            }
        }

        return Monster.checkAnyLightMonsterSpawnRules(entityType, serverLevelAccessor, mobSpawnType, blockPos, random) && notUndergroundOrIndoors && nearbyChunkHasCrop;
    }

The Utils function that gets called is the following:

public static Stream<Block> getBlocksFromChunk(LevelChunk chunk) {
        return chunk.getBlockEntities().values().stream().map(entity -> entity.getBlockState().getBlock());
    }

 

Edited February 20, 20223 yr by yeetsche420

The subscriber maybe, but the when I was debugging the predicate I was hitting the breakpoint after world gen.

I figured it out. I'll post what I did in case anyone else is doing something similar to what I'm doing. My predicate code is the same with the exception that chunks are retrieved with serverLevelAccessor.getChunk instead of level.getChunkAt. My utility function for getting the blocks from a chunk is the following:

public static Stream<Block> getBlocksFromChunk(ChunkAccess chunk) {
    if (chunk instanceof LevelChunk levelChunk) {
      List<Block> blocks = new ArrayList<>();
      Arrays.stream(levelChunk.getSections()).forEach(section -> section.getStates().getAll(blockState -> blocks.add(blockState.getBlock())));
      return blocks.stream();
    }
    else {
      return Stream.empty();
    }
}