Pre-release protocol

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Revision as of 18:59, 27 February 2016 by Rom1504 (talk | contribs) (→‎Entity Look And Relative Move: update packet description due to byte -> short)
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This page documents the changes from the last stable Minecraft release (currently 1.8.9, protocol 47) to the current pre-release (currently 1.9-pre4, protocol 106). Note that this page contains bleeding-edge information that may not be completely or correctly documented.

One who wishes to commandeer the merging of this into Protocol when an update is made must be sure to respect any changes that may have occurred to the respective packets there.

Contents

Data types

Packets

ID Packet name Documentation
Handshaking serverbound
0x00 Handshake Current Pre
Play clientbound
0x0E 0x00 Spawn Object Current Pre
0x11 0x01 Spawn Experience Orb Current Pre
0x2C 0x02 Spawn Global Entity Current Pre
0x0F 0x03 Spawn Mob Current Pre
0x10 0x04 Spawn Painting Current (unchanged)
0x0C 0x05 Spawn Player Current Pre
0x0B 0x06 Animation Current (unchanged)
0x37 0x07 Statistics Current (unchanged)
0x25 0x08 Block Break Animation Current (unchanged)
0x35 0x09 Update Block Entity Current (unchanged)
0x24 0x0A Block Action Current (unchanged)
0x23 0x0B Block Change Current (unchanged)
0x0C Boss Bar Pre
0x41 0x0D Server Difficulty Current (unchanged)
0x3A 0x0E Tab-Complete Current (unchanged)
0x02 0x0F Chat Message Current (unchanged)
0x22 0x10 Multi Block Change Current (unchanged)
0x32 0x11 Confirm Transaction Current (unchanged)
0x2E 0x12 Close Window Current (unchanged)
0x2D 0x13 Open Window Current (unchanged)
0x30 0x14 Window Items Current (unchanged)
0x31 0x15 Window Property Current (unchanged)
0x2F 0x16 Set Slot Current (unchanged)
0x17 Set Cooldown Pre
0x3F 0x18 Plugin Message Current (unchanged)
0x2F 0x19 Named Sound Effect Current Pre
0x40 0x1A Disconnect Current (unchanged)
0x1A 0x1B Entity Status Current Pre
0x27 0x1C Explosion Current (unchanged)
0x1D Unload Chunk Pre
0x2B 0x1E Change Game State Current (unchanged)
0x00 0x1F Keep Alive Current (unchanged)
0x21 0x20 Chunk Data Current Pre
0x28 0x21 Effect Current (unchanged)
0x2A 0x22 Particle Current (unchanged)
0x01 0x23 Join Game Current (unchanged)
0x34 0x24 Map Current Pre
0x15 0x25 Entity Relative Move Current (unchanged)
0x17 0x26 Entity Look And Relative Move Current Pre
0x16 0x27 Entity Look Current Pre
0x14 0x28 Entity Current (unchanged)
0x29 Vehicle Move Pre
0x36 0x2A Open Sign Editor Current (unchanged)
0x39 0x2B Player Abilities Current (unchanged)
0x42 0x2C Combat Event Current Pre
0x38 0x2D Player List Item Current (unchanged)
0x08 0x2E Player Position And Look Current Pre
0x0A 0x2F Use Bed Current (unchanged)
0x13 0x30 Destroy Entities Current (unchanged)
0x1E 0x31 Remove Entity Effect Current (unchanged)
0x48 0x32 Resource Pack Send Current (unchanged)
0x07 0x33 Respawn Current (unchanged)
0x19 0x34 Entity Head Look Current (unchanged)
0x44 0x35 World Border Current (unchanged)
0x43 0x36 Camera Current (unchanged)
0x09 0x37 Held Item Change Current (unchanged)
0x3D 0x38 Display Scoreboard Current (unchanged)
0x1C 0x39 Entity Metadata Current (unchanged)
0x1B 0x3A Attach Entity Current (unchanged)
0x12 0x3B Entity Velocity Current (unchanged)
0x04 0x3C Entity Equipment Current Pre
0x1F 0x3D Set Experience Current (unchanged)
0x06 0x3E Update Health Current (unchanged)
0x3B 0x3F Scoreboard Objective Current (unchanged)
0x40 Set Passengers Pre
0x3E 0x41 Teams Current Pre
0x3C 0x42 Update Score Current (unchanged)
0x05 0x43 Spawn Position Current (unchanged)
0x03 0x44 Time Update Current (unchanged)
0x45 0x45 Title Current (unchanged)
0x33 0x46 Update Sign Current (unchanged)
0x47 Sound Effect Pre
0x47 0x48 Player List Header And Footer Current (unchanged)
0x0D 0x49 Collect Item Current (unchanged)
0x18 0x4A Entity Teleport Current Pre
0x20 0x4B Entity Properties Current Pre
0x1D 0x4C Entity Effect Current (unchanged)
0x26 Map Chunk Bulk Current
0x46 Set Compression Current
0x49 Update Entity NBT Current
Play serverbound
0x00 Teleport Confirm Pre
0x14 0x01 Tab-Complete Current Pre
0x01 0x02 Chat Message Current (unchanged)
0x16 0x03 Client Status Current Pre
0x15 0x04 Client Settings Current Pre
0x0F 0x05 Confirm Transaction Current (unchanged)
0x11 0x06 Enchant Item Current (unchanged)
0x0E 0x07 Click Window Current (unchanged)
0x0D 0x08 Close Window Current (unchanged)
0x17 0x09 Plugin Message Current (unchanged)
0x02 0x0A Use Entity Current Pre
0x00 0x0B Keep Alive Current (unchanged)
0x04 0x0C Player Position Current (unchanged)
0x06 0x0D Player Position And Look Current (unchanged)
0x05 0x0E Player Look Current (unchanged)
0x03 0x0F Player Current (unchanged)
0x10 Vehicle Move (serverbound) Pre
0x11 Steer Boat Pre
0x13 0x12 Player Abilities Current (unchanged)
0x07 0x13 Player Digging Current Pre
0x0B 0x14 Entity Action Current Pre
0x0C 0x15 Steer Vehicle Current (unchanged)
0x19 0x16 Resource Pack Status Current (unchanged)
0x09 0x17 Held Item Change Current (unchanged)
0x10 0x18 Creative Inventory Action Current (unchanged)
0x12 0x19 Update Sign Current Pre
0x0A 0x1A Animation Current Pre
0x18 0x1B Spectate Current (unchanged)
0x08 0x1C Player Block Placement Current Pre
0x1D Use Item Pre
Status clientbound
0x00 Response Current (unchanged)
0x01 Pong Current (unchanged)
Status serverbound
0x00 Request Current (unchanged)
0x01 Ping Current (unchanged)
Login clientbound
0x00 Disconnect Current (unchanged)
0x01 Encryption Request Current (unchanged)
0x02 Login Success Current (unchanged)
0x03 Set Compression Current (unchanged)
Login serverbound
0x00 Login Start Current (unchanged)
0x01 Encryption Response Current (unchanged)

New/modified data types

Chunk Section

Format is now:

Field Name Field Type Notes
Bits Per Block Unsigned Byte How many bits per block in Data Array. If 0, the Palette Length and Palette fields are omitted and the global palette (with 13 bits per block) is used.
Palette Length Optional VarInt Length of the following array
Palette Optional Array of VarInt Mapping of block state IDs in the global palette to indices of this array
Data Array Length VarInt Number of bytes in the following array, divided by 8 (given as such because Notchian implements Data Array as an Array of Long)
Data Array Byte Array List of 4096 indices pointing to state IDs in the Palette, followed by padding to round the length up to the next multiple of 8 bytes
Block Light Byte Array Half byte per block
Sky Light Optional Byte Array Only if in the Overworld; half byte per block

Data Array, Block Light, and Sky Light are given for each block with increasing x coordinates, within rows of increasing z coordinates, within layers of increasing y coordinates.

The global palette encodes a block as 13 bits. It uses the block ID for the first 9 bits, and the block damage value for the last 4 bits. For example, diorite (block ID 1 for minecraft:stone with damage 3) would be encoded as 000000001 0011.

Entity Metadata

Format is now an array of entries, each of which looks like the following:

Name Type Meaning
Index Unsigned Byte Unique index key determining the meaning of the following value, see the table below. If this is 0xff then the it is the end of the Entity Metadata array and no more is read.
Type Optional Byte Enum Only if Index is not 0xff; the type of the index, see the table below
Value Optional value of Type Only if Index is not 0xff: the value of the metadata field
Value of Type field Type of Value field Notes
0 Byte
1 VarInt
2 Float
3 String
4 Chat
5 Slot
6 Boolean
7 Vector3F (Array of Float) 3 elements
8 Position
9 OptPosition (Boolean + Optional Position) Position is present if the Boolean is set to true
10 Direction (VarInt) ???
11 OptUUID (Boolean + Optional UUID) UUID is present if the Boolean is set to true
12 BlockID (VarInt) id << 4 | data
Entity class Index Type Meaning
Entity 0 Byte Status bit mask, added 0x40 - glowing effect.
1 VarInt Air
2 String Custom Name
3 Boolean Is Custom Name Visible
4 Boolean Is Silent
AreaEffectCloud extends Entity 5 Float Radius
6 VarInt Color (only for mob spell particle)
7 Boolean Unknown (seems that true value ignore radius and show effect as single point, not area)
8 VarInt Particle ID
Arrow extends Entity 5 Byte Is Critical
TippedArrow extends Arrow 6 VarInt Color
Boat extends Entity 5 VarInt Time Since Last Hit
6 VarInt Forward Direction
7 Float Damage Taken
8 VarInt Type
EnderCrystal extends Entity 5 OptPosition Beam Target
6 Boolean Show Bottom
Fireball extends Entity no additional metadata
WitherSkull extends Fireball 5 Boolean Invulnerable
Fireworks extends Entity 5 Slot Firework Info
Hanging extends Entity no additional metadata
ItemFrame extends Hanging 5 Slot Item
6 VarInt Rotation
Item extends Entity 5 Slot Item
Living extends Entity 5 Byte Unknown (probably indicates which hand is currently used)
6 Float Health
7 VarInt Potion Effect Color
8 Boolean Is Potion Effect Ambient
9 VarInt Number of Arrows in Entity
ArmorStand extends Living
10 Byte Status bit mask
11 Vector3F Head rotation
12 Vector3F Body rotation
13 Vector3F Left arm rotation
14 Vector3F Right arm rotation
15 Vector3F Left leg rotation
16 Vector3F Right leg rotation
Insentient extends Living 10 Byte Status bit mask (NoAI, Left handed)
Ambient extends Insentient no additional metadata
Bat extends Ambient 11 Byte Is Hanging
Creature extends Insentient no additional metadata
Ageable extends Creature 11 Boolean Is Baby
Animal extends Ageable no additional metadata
Horse extends Animal 12 Byte Status bit mask
13 VarInt Type
14 VarInt Variant
15 OptUUID Owner's UUID
16 VarInt Armor
Pig extends Animal 12 Boolean Has Saddle
Rabbit extends Animal 12 VarInt Type
Sheep extends Animal 12 Byte Status bit mask
TameableAnimal extends Animal 12 Byte Status bit mask (sitting, tamed)
13 OptUUID Owner's UUID
Ocelot extends TameableAnimal 14 VarInt Type
Wolf extends TameableAnimal 14 Float Damage Taken (used for tail rotation)
15 Boolean Is Begging
16 VarInt Collar Color
Villager extends Ageable 12 VarInt Unknown
Golem extends Creature no additional metadata
IronGolem extends Golem 11 Byte Is Player Created
Shulker extends Golem 11 Direction Facing Direction
12 OptPosition Attachment Position
13 Byte Shield Height
Monster extends Creature no additional metadata
Blaze extends Monster 11 Byte Is On Fire
Creeper extends Monster 11 VarInt State (-1 = Idle, 1 = Fuse)
12 Boolean Is Powered
13 Boolean Is Ignited
Guardian extends Monster 11 Byte Status bit mask (elderly, retracting spikes)
12 VarInt Target EID
Skeleton extends Monster 11 VarInt Type
12 Boolean Unknown (something hand related)
Spider extends Monster 11 Byte Is Climbing
Witch extends Monster 11 Boolean Is Aggresive
Wither extends Monster 11 VarInt First Head's Target
12 VarInt Second Head's Target
13 VarInt Third Head's Target
14 VarInt Invulnerable Time
Zombie extends Monster 11 Boolean Is Baby
12 VarInt Is Villager (profession)
13 Boolean Is Converting
14 Boolean Are Hands Rised Up
Enderman extends Monster 11 Block ID Carried Block
12 Boolean Is Screaming
EnderDragon extends Insentient 11 VarInt Dragon Phase
Flying extends Insentient no additional metadata
Ghast extends Flying 11 Boolean Is Attacking
Slime extends Insentient 11 VarInt Size
Minecart extends Entity 5 VarInt Shaking Power
6 VarInt Shaking Direction
7 Float Shaking Multiplier
8 VarInt Block ID and Meta
9 VarInt Block Y Position
10 Boolean Show Block
MinecartCommandBlock extends Minecart 11 String Command
12 Chat Last Output
MinecartFurnace extends Minecart 11 Boolean Is Powered
TNTPrimed extends Entity 5 VarInt Fuse Time

Entity classes also recursively use fields from classes they extend.

Handshaking

Clientbound

No changes so far.

Serverbound

Handshake

This causes the server to switch into the target state.

Packet ID State Bound To Field Name Field Type Notes
0x00 Handshaking Server Protocol Version VarInt See protocol version numbers (currently 47 106)
Server Address String hostname or IP, e.g. localhost or 127.0.0.1 (does this support IPv6?)
Server Port Unsigned Short default is 25565
Next State VarInt Enum 1 for status, 2 for login

Play

Clientbound

Spawn Object

Sent by the server when a vehicle or other object is created.

Packet ID State Bound To Field Name Field Type Notes
0x0E 0x00 Play Client Entity ID VarInt EID of the object
Object UUID UUID
Type Byte The type of object (see Entities#Objects)
X Int Double
Y Int Double
Z Int Double
Pitch Angle
Yaw Angle
Data Int Meaning dependent on the value of the Type field, see Object Data for details.
Velocity X Optional Short Short Only sent if the Data field is nonzero. Same units as Entity Velocity.
Velocity Y Optional Short Short Only sent if the Data field is nonzero. Same units as Entity Velocity.
Velocity Z Optional Short Short Only sent if the Data field is nonzero. Same units as Entity Velocity.

Spawn Experience Orb

Spawns one or more experience orbs.

Packet ID State Bound To Field Name Field Type Notes
0x11 0x01 Play Client Entity ID VarInt Entity's ID
X Int Double
Y Int Double
Z Int Double
Count Short The amount of experience this orb will reward once collected

Spawn Global Entity

With this packet, the server notifies the client of thunderbolts striking within a 512 block radius around the player. The coordinates specify where exactly the thunderbolt strikes.

Packet ID State Bound To Field Name Field Type Notes
0x2C 0x02 Play Client Entity ID VarInt The EID of the thunderbolt
Type Byte The global entity type, currently always 1 for thunderbolt
X Int Double
Y Int Double
Z Int Double


Spawn Mob

Sent by the server when a mob entity is spawned.

Packet ID State Bound To Field Name Field Type Notes
0x0F 0x03 Play Client Entity ID VarInt
Entity UUID UUID
Type Unsigned Byte The type of mob. See Entities#Mobs
X Int Double
Y Int Double
Z Int Double
Yaw Angle
Pitch Angle
Head Pitch Angle
Velocity X Short Same units as Entity Velocity
Velocity Y Short Same units as Entity Velocity
Velocity Z Short Same units as Entity Velocity
Metadata Entity Metadata

Spawn Player

This packet is sent by the server when a player comes into visible range, not when a player joins.

This packet must be sent after the Player List Item (Play, 0x38, clientbound) packet that adds the player data for the client to use when spawning a player. If the Player List Item for the player spawned by this packet is not present when this packet arrives, Notchian clients will not spawn the player entity. The Player List Item packet includes skin/cape data.

Servers can, however, safely spawn player entities for players not in visible range. The client appears to handle it correctly.

When in online-mode the UUIDs must be valid and have valid skin blobs, in offline-mode UUID v3 is used.

For NPCs UUID v2 should be used. Note: 

<+Grum> i will never confirm this as a feature you know that :)

In an example UUID, xxxxxxxx-xxxx-Yxxx-xxxx-xxxxxxxxxxxx, the UUID version is specified by Y. So, for UUID v3, Y will always be 3, and for UUID v2, Y will always be 2.

Packet ID State Bound To Field Name Field Type Notes
0x0C 0x05 Play Client Entity ID VarInt Player's EID
Player UUID UUID
X Int Double
Y Int Double
Z Int Double
Yaw Angle
Pitch Angle
Current Item Short The item the player is currently holding. Note that this should be 0 for “no item”, unlike -1 used in other packets.
Metadata Entity Metadata

Boss Bar

Packet ID State Bound To Field Name Field Type Notes
0x49 0x0C Play Client UUID UUID Unique ID for this bar
Action VarInt Enum Determines the layout of the remaining packet
Action Field Name
0: add Title Chat
Health Float From 0 to 1. Values greater than 1 do not crash the client, and start rendering part of a second health bar at around 1.5.
Color VarInt Enum Color ID (see below)
Division VarInt Enum Type of division (see below)
Flags Unsigned Byte Bit mask: 0x1 should darken sky, 0x2: is dragon bar (used to play end music)
1: remove no fields no fields Removes this boss bar
2: update health Health Float as above
3: update title Title Chat
4: update style Color VarInt Enum Color ID (see below)
Dividers VarInt Enum as above
5: update flags Flags Unsigned Byte as above
ID Color
0 Pink
1 Blue
2 Red
3 Green
4 Yellow
5 Purple
6 White
ID Type of division
0 No division
1 6 notches
2 10 notches
3 12 notches
4 20 notches

Set Cooldown

Applies a cooldown period to an item type.

Packet ID State Bound To Field Name Field Type Notes
0x17 Play Client Item ID VarInt ID of the item to apply a cooldown to.
Cooldown Ticks VarInt Number of ticks to apply a cooldown for.

Named Sound Effect

Packet ID State Bound To Field Name Field Type Notes
0x2F 0x19 Play Client Sound Name String All known sound effect names can be seen here
Sound Category VarInt Enum The category that this sound will be played from (current categories)
Effect Position X Int Effect X multiplied by 8
Effect Position Y Int Effect Y multiplied by 8
Effect Position Z Int Effect Z multiplied by 8
Volume Float 1 is 100%, can be more
Pitch Unsigned Byte 63 is 100%, can be more

Entity Status

Packet ID State Bound To Field Name Field Type Notes
0x1A 0x1B Play Client Entity ID Int
Entity Status Byte Enum See below
Entity Status Meaning
1 Sent when resetting a mob spawn minecart's timer — appears to be unused by the client
2 Living Entity hurt
3 Living Entity dead
4 Iron Golem throwing up arms
6 Wolf/Ocelot/Horse taming — Spawn “heart” particles
7 Wolf/Ocelot/Horse tamed — Spawn “smoke” particles
8 Wolf shaking water — Trigger the shaking animation
9 (of self) Eating accepted by server
10 Sheep eating grass
10 Play TNT ignite sound
11 Iron Golem handing over a rose
12 Villager mating — Spawn “heart” particles
13 Spawn particles indicating that a villager is angry and seeking revenge
14 Spawn happy particles near a villager
15 Witch animation — Spawn “magic” particles
16 Play zombie converting into a villager sound
17 Firework exploding
18 Animal in love (ready to mate) — Spawn “heart” particles
19 Reset squid rotation
20 Spawn explosion particle — works for some living entities
21 Play guardian sound — works for every entity
22 Enables reduced debug for players
23 Disables reduced debug for players
24–28 Sets op permission level 0–4 for players

Unload Chunk

Tells the client to unload a chunk.

Packet ID State Bound To Field Name Field Type Notes
0x1D Play Client Chunk X Int Chunk X coordinate
Chunk Z Int Chunk Z coordinate

Chunk Data

Chunk pillars are not unloaded by the client automatically. To unload chunk pillars, send this packet with Ground-Up Continuous=true and no 16^3 chunks (eg. Primary Bit Mask=0) send an Unload Chunk packet with the chunk's X and Z coordinates. The server only sends skylight information for chunk pillars in the Overworld, it's up to the client to know in which dimenison the player is currently located. You can also infer this information from the primary bitmask and the amount of uncompressed bytes sent.

Packet ID State Bound To Field Name Field Type Notes
0x21 0x20 Play Client Chunk X Int Chunk X coordinate
Chunk Z Int Chunk Z coordinate
Ground-Up Continuous Boolean This is true if the packet represents all chunk sections in this vertical chunk column, where the Primary Bit Mask specifies exactly which chunk sections are included, and which are air.
Primary Bit Mask Unsigned Short VarInt Bitmask with bits set to 1 for every 16×16×16 chunk section whose data follows in the compressed data. The least significant bit represents the chunk section at the bottom of the chunk column (from y=0 to y=15).
Size VarInt Size of Data in bytes, plus size of Biomes in bytes if present
Data Array of Chunk Section The length of the array is equal to the number of bits set in Primary Bit Mask.
Biomes Optional Byte Array Only if Ground-Up Continuous: biome array, byte per XZ coordinate, 256 bytes total.

Map

Updates a rectangular area on a map item.

Packet ID State Bound To Field Name Field Type Notes
0x34 0x24 Play Client Item Damage VarInt The damage value (map ID) of the map being modified
Scale Byte From 0 for a fully zoomed-in map (1 block per pixel) to 4 for a fully zoomed-out map (16 blocks per pixel)
Tracking Position Boolean Specifies whether the icons are shown
Icon Count VarInt Number of elements in the following array
Icon Direction And Type Array Byte 0xF0 = Direction, 0x0F = Type
X Byte
Z Byte
Columns Byte Number of columns updated
Rows Optional Byte Only if Columns is more than 0; number of rows updated
X Optional Byte Only if Columns is more than 0; x offset of the westernmost column
Z Optional Byte Only if Columns is more than 0; z offset of the northernmost row
Length Optional VarInt Only if Columns is more than 0; length of the following array
Data Optional Array of Byte Enum Only if Columns is more than 0; see Map item format

Entity Relative Move

This packet is sent by the server when an entity moves less then 1024 blocks; if an entity moves more than 1024 blocks Entity Teleport should be sent instead.

This packet allows at most 1024 blocks movement in any direction, because short range is from -32768 to -32767.

Packet ID State Bound To Field Name Field Type Notes
0x15 0x25 Play Client Entity ID VarInt
Delta X Byte Short Change in X position as a Fixed-Point number
Delta Y Byte Short Change in Y position as a Fixed-Point number
Delta Z Byte Short Change in Z position as a Fixed-Point number
On Ground Boolean

Entity Look And Relative Move

This packet is sent by the server when an entity rotates and moves. Since a short range is limited from -32768 to 32767, and movement is offset of fixed-point numbers, this packet allows at most 1024 blocks movement in any direction. (-32768/32 == -1024)

Packet ID State Bound To Field Name Field Type Notes
0x17 0x26 Play Client Entity ID VarInt
Delta X Byte Short Change in X position as a Fixed-Point number
Delta Y Byte Short Change in Y position as a Fixed-Point number
Delta Z Byte Short Change in Z position as a Fixed-Point number
Yaw Angle New angle, not a delta
Pitch Angle New angle, not a delta
On Ground Boolean

Vehicle Move

Note that all fields use absolute positioning and do not allow for relative positioning.

Packet ID State Bound To Field Name Field Type Notes
0x29 Play Client X Double Absolute position (X coordinate)
Y Double Absolute position (Y coordinate)
Z Double Absolute position (Z coordinate)
Yaw Float Absolute rotation on the vertical Axis, in degrees
Pitch Float Absolute rotation on the horizontal Axis, in degrees

Combat Event

Packet ID State Bound To Field Name Field Type Notes
0x42 0x2C Play Client Event VarInt Enum Determines the layout of the remaining packet
Event Field Name
0: enter combat no fields no fields
1: end combat Duration VarInt
Entity ID Int
2: entity dead Player ID VarInt
Entity ID Int
Message String Chat

Player Position And Look

Updates the player's position on the server.

If the distance between the last known position of the player on the server and the new position set by this packet is greater than 100 meters, the client will be kicked for “You moved too quickly :( (Hacking?)”.

Also if the fixed-point number of X or Z is set greater than 3.2E7D the client will be kicked for “Illegal position”.

Yaw is measured in degrees, and does not follow classical trigonometry rules. The unit circle of yaw on the XZ-plane starts at (0, 1) and turns counterclockwise, with 90 at (-1, 0), 180 at (0, -1) and 270 at (1, 0). Additionally, yaw is not clamped to between 0 and 360 degrees; any number is valid, including negative numbers and numbers greater than 360.

Pitch is measured in degrees, where 0 is looking straight ahead, -90 is looking straight up, and 90 is looking straight down.

The yaw in degrees of a player standing at point (x0, z0) and looking towards point (x, z) can be calculated with: 

l = x-x0
w = z-z0
c = sqrt( l*l + w*w )
alpha1 = -arcsin(l/c)/PI*180
alpha2 =  arccos(w/c)/PI*180
if alpha2 > 90 then
    yaw = 180 - alpha1
else
    yaw = alpha1

You can get a unit vector from a given yaw/pitch via: 

x = -cos(pitch) * sin(yaw)
y = -sin(pitch)
z =  cos(pitch) * cos(yaw)
Packet ID State Bound To Field Name Field Type Notes
0x08 0x2E Play Client X Double Absolute or relative position, depending on Flags
Y Double Absolute or relative position, depending on Flags
Z Double Absolute or relative position, depending on Flags
Yaw Float Absolute or relative rotation on the X Axis, in degrees
Pitch Float Absolute or relative rotation on the Y Axis, in degrees
Flags Byte Bit field, see below
Teleport ID VarInt Client should confirm this packet with Teleport Confirm containing the same Teleport ID

About the Flags field: 

<Dinnerbone> It's a bitfield, X/Y/Z/Y_ROT/X_ROT. If X is set, the x value is relative and not absolute.
Field Bit
X 0x01
Y 0x02
Z 0x04
Y_ROT 0x08
X_ROT 0x10

Entity Equipment

Packet ID State Bound To Field Name Field Type Notes
0x04 0x3C Play Client Entity ID VarInt Entity's EID
Slot Short VarInt Enum Equipment slot. 0: main hand, 1: off hand, 1–4 2–5: armor slot (2: boots, 3: leggings, 4: chestplate, 5: helmet)
Item Slot

Set Passengers

Packet ID State Bound To Field Name Field Type Notes
0x40 Play Client Entity ID VarInt Vehicle's EID
Passengers Array of VarInt EIDs of entity's passengers

Teams

Creates and updates teams.

Packet ID State Bound To Field Name Field Type Notes
0x3E 0x41 Play Client Team Name String A unique name for the team. (Shared with scoreboard).
Mode Byte Enum 0: create team, 1: remove team, 2: update team info; 3: add players to team; 4: remove players from team
Team Display Name Optional String Only if Mode is 0 or 2.
Team Prefix Optional String Only if Mode is 0 or 2. Displayed before the players' name that are part of this team.
Team Suffix Optional String Only if Mode is 0 or 2. Displayed after the players' name that are part of this team.
Friendly Fire Optional Byte Only if Mode is 0 or 2. 0 for off, 1 for on, 3 for seeing friendly invisibles.
Name Tag Visibility Optional String Only if Mode is 0 or 2. always, hideForOtherTeams, hideForOwnTeam, never.
Collision Rule Optional String Only if Mode is 0 or 2. always, hideForOtherTeams (sic), hideForOwnTeam (sic), never
Color Optional Byte Only if Mode is 0 or 2. Same as Chat colors.
Player Count Optional VarInt Only if Mode is 0 or 3 or 4. Number of players in the array.
Players Optional Array of String Only if Mode is 0 or 3 or 4. Players to be added/remove from the team. Max 40 characters so may be uuid's later.

Sound Effect

Packet ID State Bound To Field Name Field Type Notes
0x47 Play Client Sound ID VarInt ID of hardcoded sound event (events)
Sound Category VarInt Enum The category that this sound will be played from (current categories)
Effect Position X Int Effect X multiplied by 8
Effect Position Y Int Effect Y multiplied by 8
Effect Position Z Int Effect Z multiplied by 8
Volume Float 1.0 is 100%, capped between 0.0 and 1.0 by vanilla client
Pitch Unsigned Byte Float multiplied by 63.5, capped between 0.5 and 2.0 by vanilla client

Entity Teleport

This packet is sent by the server when an entity moves more than 4 blocks.

Packet ID State Bound To Field Name Field Type Notes
0x18 0x4A Play Client Entity ID VarInt
X Int Double
Y Int Double
Z Int Double
Yaw Angle New angle, not a delta
Pitch Angle New angle, not a delta
On Ground Boolean

Entity Properties

Packet ID State Bound To Field Name Field Type Notes
0x20 0x4B Play Client Entity ID VarInt
Number Of Properties Int Number of elements in the following array
Property Key Array String See below
Value Double See below
Number Of Modifiers VarInt Number of elements in the following array
Modifiers Array of Modifier Data See Attribute#Modifiers. Modifier Data defined below.

Known Key values (see also Attribute#Modifiers):

Key Default Min Max Label
generic.maxHealth 20.0 0.0 Double.MaxValue 1024.0 Max Health
generic.followRange 32.0 0.0 2048.0 Follow Range
generic.knockbackResistance 0.0 0.0 1.0 Knockback Resistance
generic.movementSpeed 0.699999988079071 0.0 Double.MaxValue 1024.0 Movement Speed
generic.attackDamage 2.0 0.0 Double.MaxValue 2048.0 Attack Damage
generic.attackSpeed 4.0 0.0 1024.0 Attack Speed
horse.jumpStrength 0.7 0.0 2.0 Jump Strength
zombie.spawnReinforcements 0.0 0.0 1.0 Spawn Reinforcements Chance

Modifier Data structure:

Field Name Field Type Notes
UUID UUID
Amount Double
Operation Byte

Map Chunk Bulk

Replaced by multiple Chunk Data packets.

Update Entity NBT

Wasn't used for anything.

Serverbound

Teleport Confirm

Sent by client as confirmation of Player Position And Look packet.

Packet ID State Bound To Field Name Field Type Notes
0x00 Play Server Teleport ID VarInt

Tab-Complete

Sent when the user presses tab while writing text.

Packet ID State Bound To Field Name Field Type Notes
0x14 0x01 Play Server Text String All text behind the cursor (e.g. to the left of the cursor in left-to-right languages like English)
Assume Command Boolean If true, the server will parse Text as a command even if it doesn't start with a /. Used in the command block GUI.
Has Position Boolean
Looked At Block Optional Position The position of the block being looked at. Only sent if Has Position is true.

Client Status

Sent when the client is ready to complete login and when the client is ready to respawn after death.

Packet ID State Bound To Field Name Field Type Notes
0x16 0x03 Play Server Action ID VarInt Enum See below

Action ID values:

Action ID Action
0 Perform respawn
1 Request stats
2 Taking Inventory achievement Open Inventory

Client Settings

Sent when the player connects, or when settings are changed.

Packet ID State Bound To Field Name Field Type Notes
0x15 0x04 Play Server Locale String e.g. en_GB
View Distance Byte Client-side render distance, in chunks
Chat Mode Byte VarInt Enum 0: enabled, 1: commands only, 2: hidden
Chat Colors Boolean “Colors” multiplayer setting
Displayed Skin Parts Unsigned Byte Skin parts, see note below
Main Hand VarInt Enum 0: Left, 1: Right

Displayed Skin Parts flags:

  • Bit 0 (0x01): Cape enabled
  • Bit 1 (0x02): Jacket enabled
  • Bit 2 (0x04): Left Sleeve enabled
  • Bit 3 (0x08): Right Sleeve enabled
  • Bit 4 (0x10): Left Pants Leg enabled
  • Bit 5 (0x20): Right Pants Leg enabled
  • Bit 6 (0x40): Hat enabled

The most significant bit (bit 7, 0x80) appears to be unused.

Use Entity

This packet is sent from the client to the server when the client attacks or right-clicks another entity (a player, minecart, etc).

A Notchian server only accepts this packet if the entity being attacked/used is visible without obstruction and within a 4-unit radius of the player's position.

Note that middle-click in creative mode is interpreted by the client and sent as a Creative Inventory Action packet instead.

Packet ID State Bound To Field Name Field Type Notes
0x02 0x0A Play Server Target VarInt
Type VarInt Enum 0: interact, 1: attack, 2: interact at
Target X Optional Float Only if Type is interact at
Target Y Optional Float Only if Type is interact at
Target Z Optional Float Only if Type is interact at
Hand Optional VarInt Enum Only if Type is interact or interact at; 0: main hand, 1: off hand

Vehicle Move (serverbound)

Sent when a player moves in a vehicle. Fields are the same as in Player Position And Look. Note that all fields use absolute positioning and do not allow for relative positioning.

Packet ID State Bound To Field Name Field Type Notes
0x10 Play Server X Double Absolute position (X coordinate)
Y Double Absolute position (Y coordinate)
Z Double Absolute position (Z coordinate)
Yaw Float Absolute rotation on the vertical Axis, in degrees
Pitch Float Absolute rotation on the horizontal Axis, in degrees

Steer Boat

Packet ID State Bound To Field Name Field Type Notes
0x11 Play Server Boolean Unknown
Boolean Unknown 2

Player Digging

Sent when the player mines a block. A Notchian server only accepts digging packets with coordinates within a 6-unit radius of the player's position.

Packet ID State Bound To Field Name Field Type Notes
0x07 0x13 Play Server Status Byte Enum The action the player is taking against the block (see below)
Location Position Block position
Face Byte Enum The face being hit (see below)

Status can be one of seven values:

Value Meaning Notes
0 Started digging
1 Cancelled digging Sent when the player lets go of the Mine Block key (default: left click)
2 Finished digging Sent when the client thinks it is finished
3 Drop item stack Triggered by using the Drop Item key (default: Q) with the modifier to drop the entire selected stack (default: depends on OS). Location is always set to 0/0/0, Face is always set to -Y.
4 Drop item Triggered by using the Drop Item key (default: Q). Location is always set to 0/0/0, Face is always set to -Y.
5 Shoot arrow / finish eating Location is always set to 0/0/0, Face is always set to Special.
6 Swap item in hand Used to swap or assign an item to the second hand. Location is always set to 0/0/0, Face is always set to -Y.

The Face field can be one of the following values, representing the face being hit (or the Special value used for “shoot arrow / finish eating”):

Value Offset Face
0 -Y Bottom
1 +Y Top
2 -Z North
3 +Z South
4 -X West
5 +X East
255 — Special

Entity Action

Sent at least when crouching, leaving a bed, or sprinting. To send action animation to client use 0x28. The client will send this with Action ID = 3 when “Leave Bed” is clicked.

Packet ID State Bound To Field Name Field Type Notes
0x0B 0x14 Play Server Entity ID VarInt Player ID
Action ID VarInt Enum The ID of the action, see below
Jump Boost VarInt Horse jump boost. Ranged from 0 to 100.

Action ID can be one of the following values:

ID Action
0 Crouch
1 Uncrouch
2 Leave bed
3 Start sprinting
4 Stop sprinting
5 Start Jump with horse
6 Stop Jump with horse
7 Open ridden horse inventory
8 Start Elytra Flying

“Open inventory” is now sent via the Client Status packet.

Update Sign

This message is sent from the client to the server when the “Done” button is pushed after placing a sign.

Packet ID State Bound To Field Name Field Type Notes
0x12 0x19 Play Server Location Position Block Coordinates
Line 1 Chat String First line of text in the sign
Line 2 Chat String Second line of text in the sign
Line 3 Chat String Third line of text in the sign
Line 4 Chat String Fourth line of text in the sign

Animation

Sent when the player's arm swings.

Packet ID State Bound To Field Name Field Type Notes
0x0A 0x1A Play Server Hand VarInt Enum Hand used for the animation

Player Block Placement

Packet ID State Bound To Field Name Field Type Notes
0x08 0x1C Play Server Location Position Block position
Face Byte VarInt Enum The face on which the block is placed (as documented at Player Digging)
Held Item Slot
Hand VarInt Enum The hand from which the block is placed; 0: main hand, 1: off hand
Cursor Position X Unsigned Byte The position of the crosshair on the block, from 0 to 15 increasing from west to east
Cursor Position Y Unsigned Byte The position of the crosshair on the block, from 0 to 15 increasing from bottom to top
Cursor Position Z Unsigned Byte The position of the crosshair on the block, from 0 to 15 increasing from north to south

In normal operation (i.e. placing a block), this packet is sent once, with the values set normally.

The Cursor Position X/Y/Z fields (also known as in-block coordinates) are calculated using raytracing. The unit corresponds to one pixel in the default resource pack. For example, let's say a slab is being placed against the south face of a full block. The Cursor Position X will be higher if the player was pointing near the right (east) edge of the face, lower if pointing near the left. The Cursor Position Y will be used to determine whether it will appear as a bottom slab (values 0–7) or as a top slab (values 8–15). The Cursor Position Z should be 15 since the player was looking at the southernmost part of the block.

This packet has a special case where X, Y, Z, and Direction are all -1. (Note that Y is unsigned so set to 255.) This special packet indicates that the currently held item for the player should have its state updated such as eating food, pulling back bows, using buckets, etc.

Special note on using buckets: When using buckets, the Notchian client might send two packets: first a normal and then a special case. The first normal packet is sent when you're looking at a block (e.g. the water you want to scoop up). This normal packet does not appear to do anything with a Notchian server. The second, special case packet appears to perform the action — based on current position/orientation and with a distance check — it appears that buckets can only be used within a radius of 6 units.

Use Item

Sent when pressing the Use Item key (default: right click) with an item in hand.

Packet ID State Bound To Field Name Field Type Notes
0x1D Play Server Hand VarInt Enum Hand used for the animation

Status

Clientbound

No changes so far.

Serverbound

No changes so far.

Login

Clientbound

No changes so far.

Serverbound

No changes so far.

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