Slime World Format

Definition

“Blob” file format
2 bytes - magic = 0xB10B
1 byte (ubyte) - version, current = 0x03
2 bytes (short) - xPos of chunk lowest x & lowest z
2 bytes (short) - zPos
2 bytes (ushort) - width
2 bytes (ushort) - depth
[depends] - chunk bitmask
  -> each chunk is 1 bit: 0 if all air (missing), 1 if present
  -> chunks are ordered zx, meaning 
  -> the last byte has unused bits on the right
  -> size is ceil((width*depth) / 8) bytes

4 bytes (int) - compressed chunks size
4 bytes (int) - uncompressed chunks size
  <array of chunks> (size determined from bitmask)
  compressed using zstd

4 bytes (int) - compressed tile entities size
4 bytes (int) - uncompressed tile entities size
  <array of tile entity nbt compounds>
  same format as mc, 
  inside an nbt list named “tiles”, in global compound, no gzip anywhere
  compressed using zstd

1 byte (boolean) - has entities
[if has entities]
  4 bytes (int) compressed entities size
  4 bytes (int) uncompressed entities size
    <array of entity nbt compounds>
    Same format as mc EXCEPT optional “CustomId”
    in side an nbt list named “entities”, in global compound
    Compressed using zstd

4 bytes (int) - compressed “extra” size
4 bytes (int) - uncompressed “extra” size
[depends] - compound tag compressed using zstd

Custom chunk format
256 ints - heightmap
256 bytes - biomes
2 bytes - sections bitmask (bottom to top)
  2048 bytes - block light
  4096 bytes - blocks
  2048 bytes - data
  2048 bytes - skylight
  2 bytes (ushort) - HypixelBlocks3 size (0 if absent)
  [depends] - HypixelBlocks3
  For each section