User:Chibill/Map Format

This page covers the world information as of 17w47a to the present. See Alpha Map Format for Alpha information. See .. for Information before the "Flattening". Though some information is also valid for before 17w47a.

General Information
Worlds 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 state array (Long Array), block light (4-bit),palette, 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). 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). Biome values are stored as bytes.

Storage
This section documents the Anvil format for servers.

Maps are stored as a specific directory structure with several NBT files within. For the sake of examples, the world we'll be working with is stored in a folder called "/world".

Directory Structure

 * /world/data: Stores extra world data (Villages,Mineshafts,Temples)
 * /world/DIM-1: Nether world
 * /world/DIM-1/region: Nether world regions
 * /world/DIM1: End world
 * /world/DIM1/region: End world regions
 * /world/players: Player data
 * /world/region: Overworld regions

level.dat
In the root directory is a level.dat file. The structure of that file is this:


 * NBTCompound(Data)
 * NBTCompound(DataPacks)
 * NBTList(Disabled)
 * NBTList(Enabled): Generally contains the string "vanilla"
 * NBTCompound(DimensionData)
 * NBTCompound(1)
 * NBTCompound(DragonFight)
 * NBTList(Gateways)
 * NBTByte(DragonKilled)
 * NBTByte(PreviouslyKilled)
 * NBTCompound(GameRules)
 * NBTString(announceAdvancemtns): One for each game rule with the value being the game rules value.
 * NBTCompound(Version)
 * NBTInt(Id): 1451 for 17w47a
 * NBTString(Name): Name of the version
 * NBTByte(Snapshot): If the version is a snapshot
 * NBTDouble(BoarderCenterX)
 * NBTDouble(BoarderCenterZ)
 * NBTDouble(BoarderDamagerPerBlock)
 * NBTDouble(BorderSafeZone)
 * NBTDouble(BoarderSize)
 * NBTDouble(BorderSizeLerpTarget)
 * NBTLong(BorderSizeLerpTime)
 * NBTDouble(BoarderWarningBlocks)
 * NBTDouble(BoarderWarningTime)
 * NBTInt(clearWeatherTime)
 * NBTInt(DataVersion)
 * NBTLong(DayTime)
 * NBTByte(Difficulty)
 * NBTByte(DifficultyLocked)
 * NBTInt(GameType)
 * NBTString(generatorName)
 * NBTString(generatorOptions)
 * NBTInt(generatorVersion)
 * NBTByte(hardcore)
 * NBTByte(initialized)
 * NBTLong(LastPlayed)
 * NBTString(LevelName)
 * NBTByte(MapFeatures): Set to 1 if structures are generated, such as villages
 * NBTByte(raining): Set to 1 if currently raining
 * NBTInt(rainTime): The ticks remaining until rain stops?
 * NBTLong(RandomSeed)
 * NBTLong(SizeOnDisk): Has been 0 since 1.2.5 (Weird? Whats the point of this?)
 * NBTInt(SpawnX)
 * NBTInt(SpawnY)
 * NBTInt(SpawnZ)
 * NBTByte(thundering): Set to 1 if currently thundering (only if there is potential for thunder, not if a thunderbolt is currently in progress)
 * NBTInt(thunderTime)
 * NBTInt(version)

[playeruuid].dat
Each player that has ever connected is given a [playeruuid].dat file.


 * NBTCompound
 * NBTCompound(abilities)
 * NBTByte(flying): 1 if flying
 * NBTFloat(flySpeed): Generally 0.05
 * NBTByte(instaBuild)
 * NBTByte(invulnerable)
 * NBTByte(mayBuild)
 * NBTByte(mayFly)
 * NBTFloat(walkSpeed): Generally 0.1
 * NBTCompound(recipeBook)
 * NBTList(recipes)
 * NBTList(toBeDisplayed)
 * NBTByte(isFilteringCraftable)
 * NBTByte(isGuiOpen)
 * NBTCompound(Attributes)
 * NBTCompound: One entry for each Attribute the player has.
 * NBTDouble(Base)
 * NBTString(Name)
 * NBTList(EnderItems)
 * NBTCompound(Inventory)
 * NBTCompound
 * NBTCompound(tag)
 * NBTInt(Damage)
 * NBTByte(Count)
 * NBTByte(Slot)
 * NBTString(id)
 * NBTList(Motion)
 * NBTDouble
 * NBTDouble
 * NBTDouble
 * NBTList(Pos)
 * NBTDouble
 * NBTDouble
 * NBTDouble
 * NBTList(Rotation)
 * NBTFloat
 * NBTFloat
 * NBTFloat(AbsorptionAmount)
 * NBTShort(Air)
 * NBTInt(DataVersion)
 * NBTShort(DeathTime)
 * NBTInt(Dimension)
 * NBTFloat(FallDistance)
 * NBTByte(FallFlying)
 * NBTShort(Fire): Ticks until the player is no longer on fire, or zero
 * NBTFloat(foodExhaustionLevel)
 * NBTInt(foodLevel)
 * NBTFloat(foodSaturationLevel)
 * NBTInt(foodTickTimer)
 * NBTShort(Health)
 * NBTInt(HurtByTimestamp)
 * NBTShort(HurtTime)
 * NBTByte(Invnerable)
 * NBTByte(OnGround)
 * NBTInt(playerGameType)
 * NBTInt(PortalCooldown)
 * NBTInt(Score)
 * NBTByte(seenCredits)
 * NBTInt(SelectedItemSlot)
 * NBTByte(Sleeping)
 * NBTShort(SleepTimer)
 * NBTLong(UUIDLeast)
 * NBTLong(UUIDMost)
 * NBTInt(XpLevel)
 * NBTFloat(XpP)
 * NBTFloat(XpSeed)
 * NBTInt(XpTotal)

[region].mca
Each region file is named "r.x.z.mca", where x and z are the coordinates. These coordinates are relative to each region. Given column coordinates, divide them by 32 to get the region coordinates.


 * NBTCompound
 * NBTCompound(Chunk [x,z]): x and z are region column coordinates, not relative to the overall world. The compound name is a misnomer, it actually represents column.
 * NBTCompound(Level)
 * NBTByte(TerrainPopulated): 1 if this column has been generated
 * NBTInt(xPos): In global, world-relative chunk coordinates
 * NBTInt(zPos): In global, world-relative chunk coordinates
 * NBTLong(LastUpdate): The last time a block changed in this column
 * NBTByte(LightPopulated)
 * NBTByte(TerrainPopulated)
 * NBTLong(InhabitedTime)
 * NBTByteArray(Biomes): Always 256 Entries
 * NBTList(Entities)
 * NBTCompound
 * NBTByte(OnGround)
 * NBTShort(Air)
 * NBTShort(AttackTime)
 * NBTShort(DeathTime)
 * NBTShort(Fire)
 * NBTShort(Health)
 * NBTShort(HurtTime)
 * NBTFloat(FallDistance)
 * NBTString(id): Example: "Skeleton"
 * NBTList(Motion)
 * NBTDouble
 * NBTDouble
 * NBTDouble
 * NBTList(Pos)
 * NBTDouble
 * NBTDouble
 * NBTDouble
 * NBTList(Rotation)
 * NBTFloat
 * NBTFloat
 * NBTList(Sections): Chunks
 * NBTCompound
 * NBTByte(Y): 0-16
 * NBTByteArray(BlockLight)
 * NBTLongArray(BlockStates)
 * NBTList(Palette): Holds the palette for the blocks stored in the NBTLongArray. They are stored much in the same way as in the Chunk Data Packet. See Chunk_Format
 * NBTCompound
 * NBTString(Name)
 * NBTCompound
 * NBTString(Name)
 * NBTCompound(Properties)
 * NBTString : Key is the name of the property being saved
 * NBTByteArray(SkyLight)
 * NBTList(TileEntities)
 * NBTIntArray(HeightMap): 256 entries