Data3D (+) Format

Byte Order

Data3D data is stored in Little Endian byte order.

Parsing Data3D

Name	Size (in bytes)	Description
Heightmap	512	The heightmap for the chunk. Subtract 64 to get the real Y coordinate. Stored as 16-bit integers. ZX order (Z increments first)

Loop next section 24 times until you have parsed all subchunks biome palettes.

Name	Size (in bits)	Description
Palette Version	1	Seems to always be 1
Bits Per Word	7	How many bits are used for each word. If 127 skip to reading the next palette version/bits per word (null section). If 0 skip to reading a single Biome ID.

If Version is 1

Name	Size (in bytes)	Description
Biome Indices	ceil(4096[1] ÷ Blocks Per Word[2]) × 4	Stored as Blocks Per Word indices, with each unsigned 32-bit integer containing multiple indices, each occupying Bits Per Word bits. The indices are packed and stored in YZX order (Y increments first).
Palette Size	4	The number of Biome palettes stored.

Now loop the next section Palette Size times until you have parsed all biome ids.

Name	Size (in byte)	Description
Biome ID	4	A biome Id. Stored as 32-bit unsigned integers.

Notes

1. In some languages you may need to write this as 4096.0 instead of just 4096 for the correct output.
2. Blocks Per Word = floor(32 ÷ Bits Per Word)