Difference between revisions of "Map Format"

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This page covers the map information as of 1.2.4.  See [[Alpha Map Format]] for Alpha information.
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=General Information=
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Maps are represented as a series of regions, within which are a number of columns, and chunks.  Each region is 32x1x32 columns, each column is 1x16x1 chunks, and each chunk is 16x16x16 blocks.  The overall block height of a column is 256.  Each chunk stores four (or five) things - block IDs (8-bit), block metadata (4-bit), block light (4-bit), and sky light (4-bit).  Block light is light cast by things like torches and glowstone, and is calculated with a 3D [http://en.wikipedia.org/wiki/Flood_fill Flood Fill] algorithm.  Sky light is the light cast by the sky, and is calculated by starting at the top and working your way down.  As you pass through semi-transparent blocks, you decrease the lighting value until you hit an opaque block.  The opaque block is the last block whose skylight has a nonzero value.  Lighting starts at 0xF (brightest) and works down to 0x0 (dimmest).  Map columns store biome information.  Each 1x256x1 cuboid of blocks has the same biome value, for a total of 256 possible biome values per chunk (16x16).
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=Protocol=
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For sending map packets to a client, some information is required.
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=Storage=

Revision as of 20:30, 27 March 2012

This page covers the map information as of 1.2.4. See Alpha Map Format for Alpha information.

General Information

Maps are represented as a series of regions, within which are a number of columns, and chunks. Each region is 32x1x32 columns, each column is 1x16x1 chunks, and each chunk is 16x16x16 blocks. The overall block height of a column is 256. Each chunk stores four (or five) things - block IDs (8-bit), block metadata (4-bit), block light (4-bit), and sky light (4-bit). Block light is light cast by things like torches and glowstone, and is calculated with a 3D Flood Fill algorithm. Sky light is the light cast by the sky, and is calculated by starting at the top and working your way down. As you pass through semi-transparent blocks, you decrease the lighting value until you hit an opaque block. The opaque block is the last block whose skylight has a nonzero value. Lighting starts at 0xF (brightest) and works down to 0x0 (dimmest). Map columns store biome information. Each 1x256x1 cuboid of blocks has the same biome value, for a total of 256 possible biome values per chunk (16x16).

Protocol

For sending map packets to a client, some information is required.

Storage