Protocol:zh-cn

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注意!

本文是关于MinecraftJava版最新稳定版的协议. (1.18.1, 协议757). 关于 Java 版的 Pre-releases, 详见Pre-release protocol. For the incomplete Bedrock Edition docs, see Bedrock Protocol. For the old Pocket Edition, see Pocket Edition Protocol Documentation.

本页介绍了对Minecraft协议的解析.

如果你遇到困难,看一下FAQ或者在IRC上询问irc.libera.chat上的#mcdevs(更多信息).

注意: 虽然你可以不受限制地使用本页面的内容来创建服务器、客户端、机器人等,但是如果你将本页的任何内容复制到其他地方发表,你仍然需要以#mcdevs署名.

各个版本之间的变化可在协议历史查看

Contents

定义

Minecraft服务器接受来自TCP客户端的连接, 并使用数据包与它们进行通信.数据包是通过TCP连接发送的一串字节.一个数据包的意义既取决于它的ID, 也取决于连接的当前状态.每个连接的初始状态是Handshaking, 并使用握手和完成登录这两个数据包进行状态切换.

数据类型

通过网络发送的所有数据（VarInt 和 VarLong 除外）都是小端序的, 即字节从最高有效字节发送到最低有效字节. 当今大多数计算机都是小端序的, 因此在用网络发送数据之前可能需要更改其字节序.

其他定义

项目 定义
玩家 当这个词是单数时中文没有单复数, 玩家是指连接到服务端的客户端
实体 实体是指任何物品、玩家、生物、矿车或船等. 有关完整列表, 请参阅 the Minecraft Wiki article .
实体 ID (EID) EID 或实体 ID 是一个用于识别特定实体的4字节序列. 实体的 EID 在整个服务器上是唯一的.
坐标 (XYZ) 在本文档中, 坐标轴名称与调试屏幕 (F3) 中显示的轴名称相同. Y轴指向上方, X轴指向东方, Z轴指向南方.
米 (Meter) 米是 Minecraft 的基本长度单位, 等于完整方块的边长. 术语块可用于表示米或立方米.
全局调色板 (Global palette) 将非负整数映射到方块状态的表/字典/调色板(palette). 方块状态ID是根据分配顺序线性创建的. 每个方块都分配了一个唯一的方块状态ID; 如果一个方块具有多个属性, 则分配的状态数是每个属性的值数的乘积. 当前属性和状态ID范围的列表可以在 burger 中找到.

此外，原版(Vanilla) 服务器现在包含了一个选项，可以通过运行 java -cp minecraft_server.jar net.minecraft.data.Main --reports来导出当前方块状态ID映射。有关更多信息，请参阅 Data Generators。

Notchian 由 Mojang 开发和发布的原版 Minecraft 的官方实现.

数据包格式

单个数据包不能超过2097151字节(the maximum that can be sent in a 3-byte VarInt). 对于压缩数据包, 这同时适用于压缩长度和未压缩长度.

无压缩

字段名 字段类型 备注
长度 (Length) VarInt 数据包ID + 数据的长度
数据包ID (Packet ID) VarInt
数据 (Data) Byte Array 取决于连接状态和数据包ID，请参阅以下部分.

压缩

一旦发送了 Set Compression 数据包 (具有非负阈值), 就会对以下所有数据包启用 zlib 压缩. 数据包的格式略有变化, 以包括未压缩数据包的大小.

是否被压缩 字段名 字段类型 备注
否 数据包长度 (Packet Length) VarInt 数据长度的长度 + 压缩过的 (数据包ID + 数据) 的长度
否 数据长度 (Data Length) VarInt 未压缩的 (Packet ID + Data) 的长度或 0
Yes 数据包ID (Packet ID) VarInt zlib 压缩的数据包ID (请参阅下面的各节)
数据 (Data) Byte Array zlib 压缩的数据 (请参阅下面的各节)

如果包含数据和数据包ID(作为VarInt)的缓冲区的大小小于 Set Compression 数据包中指定的阈值, 它将以未压缩形式发送. 这是通过将数据长度设置为0来完成的。(相当于在长度和数据包数据之间额外添加了一个0来发送非压缩格式).

如果它大于阈值，则遵循常规的压缩协议格式.

可以通过发送带有负阈值的 Set Compression 数据包，或根本不发送设置压缩数据包来禁用压缩.

Handshaking

客户端绑定

握手状态下没有客户端绑定数据包, 因为在客户端发送第一个数据包后协议会立即切换到不同的状态.

服务器绑定

握手 (Handshake)

这会导致服务器切换到目标状态.

数据包ID 状态 绑定到 字段名 字段类型 备注
0x00 握手 服务器 协议版本 (Protocol Version) VarInt 参考protocol version numbers:zh-cn (在Minecraft 1.18.1为757).
服务器地址 (Server Address) String (255) 主机名或 IP, 例如被用于连接的 localhost 或 127.0.0.1 . Notchian 服务器不使用此信息. 需要注意的是, SRV 记录仅是简单的重定向, 例如 如果 _minecraft._tcp.example.com 指向 mc.example.org，则连接到 example.com 的用户除了连接到它之外, 还将提供 example.org 作为服务器地址.
服务器端口 (Server Port) Unsigned Short 默认是 25565. Notchian 服务器并不使用此字段.
下一个状态 (Next State) VarInt Enum 为1时 状态查询:zh-cn, 为2时 登录:zh-cn.

旧版服务器列表 Ping (Legacy Server List Ping)

Warning.png 此数据包使用非标准格式. 它从不以长度为前缀, 并且数据包 ID 是Unsigned Byte而不是 VarInt.

虽然在技术上不是当前协议的一部分, 但旧客户端可能会发送此数据包以初始化 Server List Ping:zh-cn, 现代服务器应该正确处理它.

数据包ID 状态 绑定到 字段名 字段类型 备注
0xFE 握手 服务器 负载 (Payload) Unsigned Byte 恒定为1 (0x01).

请参阅 Server List Ping:zh-cn#1.6 了解此数据包之后的协议的详细信息.

状态查询

Main article: Server List Ping:zh-cn

客户端绑定

状态响应 (Status Response)

数据包ID 状态 绑定到 字段名 字段类型 备注
0x00 状态查询 客户端
JSON 响应 (JSON Response) String (32767) 请参阅Server List Ping:zh-cn#Status_Response; 与所有字符串一样, JSON 响应前面会加上 VarInt 类型的前缀.

Ping 响应 (Ping Response) (status)

数据包ID 状态 绑定到 字段名 字段类型 备注
0x01 状态查询 客户端 负载 (Payload) Long 应与客户端发送的内容相同.

服务器绑定

状态请求 (Status Request)

在握手之后、任何ping之前, 只能立即请求一次状态. 否则服务器不会响应.

数据包ID 状态 绑定到 字段名 字段类型 备注
0x00 状态查询 服务器 无字段

Ping 请求(Ping Request) (status)

数据包ID 状态 绑定到 字段名 字段类型 备注
0x01 状态查询 服务器 负载 (Payload) Long 可以是任何数字. Notchian 客户端使用以毫秒为单位的系统时间戳.

登录

登录过程如下:

  1. C→S: 握手 State=2(登录)
  2. C→S: 开始登录
  3. S→C: 加密请求
  4. 客户端认证
  5. C→S: 加密响应
  6. 服务端认证(此时CS的连接均为加密)
  7. S→C: 设置压缩 (可选)
  8. S→C: 登录完成

如果需要压缩, 必须在登录完成前发送.请注意, 在设置压缩后发送的任何东西必须使用数据包压缩格式.

For unauthenticated ("cracked"/offline-mode) and integrated servers (either of the two conditions is enough for an unencrypted connection) there is no encryption. In that case Login Start is directly followed by Login Success. The Notchian server uses UUID v3 for offline player UUIDs, with the namespace “OfflinePlayer” and the value as the player’s username. For example, Notch’s offline UUID would be derived from the string “OfflinePlayer:Notch”. This is not a requirement however, the UUID may be anything.

See Protocol Encryption for details.

Clientbound

Disconnect (login)

Packet ID State Bound To Field Name Field Type Notes
0x00 Login Client Reason Chat

加密请求

Packet ID State Bound To Field Name Field Type Notes
0x01 Login Client Server ID String (20) Appears to be empty.
Public Key Length VarInt Length of Public Key
Public Key Byte Array The server's public key in bytes
Verify Token Length VarInt Length of Verify Token. Always 4 for Notchian servers.
Verify Token Byte Array A sequence of random bytes generated by the server.

See Protocol Encryption for details.

登录完成

Packet ID State Bound To Field Name Field Type Notes
0x02 Login Client UUID UUID
Username String (16)

This packet switches the connection state to play.

Warning.png The (notchian) server might take a bit to fully transition to the Play state, so it's recommended to wait before sending Play packets, either by setting a timeout, or waiting for Play packets from the server (usually Player Info).

The notchian client doesn't send any (non-keep alive) packets until the next tick/time update packet.

设置压缩

启用压缩.如果启用了, 所有的数据包将会采用数据包压缩格式. Negative or zero values will disable compression, meaning the packet format should remain in the uncompressed packet format. However, this packet is entirely optional, and if not sent, compression will also not be enabled (the notchian server does not send the packet when compression is disabled).

Packet ID State Bound To Field Name Field Type Notes
0x03 Login Client Threshold VarInt Maximum size of a packet before it is compressed.

Login Plugin Request

Used to implement a custom handshaking flow together with Login Plugin Response.

Unlike plugin messages in "play" mode, these messages follow a lock-step request/response scheme, where the client is expected to respond to a request indicating whether it understood. The notchian client always responds that it hasn't understood, and sends an empty payload.

Packet ID State Bound To Field Name Field Type Notes
0x04 Login Client Message ID VarInt Generated by the server - should be unique to the connection.
Channel Identifier Name of the plugin channel used to send the data.
Data Byte Array Any data, depending on the channel. The length of this array must be inferred from the packet length.

Serverbound

Login Start

Packet ID State Bound To Field Name Field Type Notes
0x00 Login Server Name String (16) Player's Username.

加密响应

Packet ID State Bound To Field Name Field Type Notes
0x01 Login Server Shared Secret Length VarInt Length of Shared Secret.
Shared Secret Byte Array Shared Secret value, encrypted with the server's public key.
Verify Token Length VarInt Length of Verify Token.
Verify Token Byte Array Verify Token value, encrypted with the same public key as the shared secret.

See Protocol Encryption for details.

Login Plugin Response

Packet ID State Bound To Field Name Field Type Notes
0x02 Login Server Message ID VarInt Should match ID from server.
Successful Boolean true if the client understands the request, false otherwise. When false, no payload follows.
Data Optional Byte Array Any data, depending on the channel. The length of this array must be inferred from the packet length.

Play

Clientbound

实体生成

Sent by the server when a vehicle or other non-living entity is created.

Packet ID State Bound To Field Name Field Type Notes
0x00 Play Client Entity ID VarInt Entity ID.
Object UUID UUID
Type VarInt The type of entity (same as in Spawn Living Entity).
X Double
Y Double
Z Double
Pitch Angle To get the real pitch, you must divide this by (256.0F / 360.0F)
Yaw Angle To get the real yaw, you must divide this by (256.0F / 360.0F)
Data Int Meaning dependent on the value of the Type field, see Object Data for details.
Velocity X Short Same units as Entity Velocity. Always sent, but only used when Data is greater than 0 (except for some entities which always ignore it; see Object Data for details).
Velocity Y Short
Velocity Z Short

Spawn Experience Orb

Spawns one or more experience orbs.

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

Spawn Living Entity

Sent by the server when a living entity is spawned.

Packet ID State Bound To Field Name Field Type Notes
0x02 Play Client Entity ID VarInt
Entity UUID UUID
Type VarInt The type of mob. See Entity_metadata#Mobs.
X Double
Y Double
Z 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.

Spawn Painting

This packet shows location, name, and type of painting.

Packet ID State Bound To Field Name Field Type Notes
0x03 Play Client Entity ID VarInt
Entity UUID UUID
Motive VarInt Painting's ID, see below.
Location Position Center coordinates (see below).
Direction Byte Enum Direction the painting faces (North = 2, South = 0, West = 1, East = 3).

Calculating the center of an image: given a (width × height) grid of cells, with (0, 0) being the top left corner, the center is (max(0, width / 2 - 1), height / 2). E.g. (1, 0) for a 2×1 painting, or (1, 2) for a 4×4 painting.

List of paintings by coordinates in paintings_kristoffer_zetterstrand.png (where x and y are in pixels from the top left and width and height are in pixels or 16ths of a block):

Name ID x y width height
minecraft:kebab 0 0 0 16 16
minecraft:aztec 1 16 0 16 16
minecraft:alban 2 32 0 16 16
minecraft:aztec2 3 48 0 16 16
minecraft:bomb 4 64 0 16 16
minecraft:plant 5 80 0 16 16
minecraft:wasteland 6 96 0 16 16
minecraft:pool 7 0 32 32 16
minecraft:courbet 8 32 32 32 16
minecraft:sea 9 64 32 32 16
minecraft:sunset 10 96 32 32 16
minecraft:creebet 11 128 32 32 16
minecraft:wanderer 12 0 64 16 32
minecraft:graham 13 16 64 16 32
minecraft:match 14 0 128 32 32
minecraft:bust 15 32 128 32 32
minecraft:stage 16 64 128 32 32
minecraft:void 17 96 128 32 32
skull_and_roses 18 128 128 32 32
minecraft:wither 19 160 128 32 32
minecraft:fighters 20 0 96 64 32
minecraft:pointer 21 0 192 64 64
minecraft:pigscene 22 64 192 64 64
minecraft:burning_skull 23 128 192 64 64
minecraft:skeleton 24 192 64 64 48
minecraft:donkey_kong 25 192 112 64 48

The Minecraft Wiki article on paintings also provides a list of painting names to the actual images.

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 Info packet that adds the player data for the client to use when spawning a player. If the Player Info for the player spawned by this packet is not present when this packet arrives, Notchian clients will not spawn the player entity. The Player Info 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.

Packet ID State Bound To Field Name Field Type Notes
0x04 Play Client Entity ID VarInt Player's EID.
Player UUID UUID See below for notes on offline mode and NPCs.
X Double
Y Double
Z Double
Yaw Angle
Pitch Angle

When in online mode, the UUIDs must be valid and have valid skin blobs.

In offline mode, UUID v3 is used with the String OfflinePlayer:<player name>, encoded in UTF-8 (and case-sensitive). The Notchain server uses UUID.nameUUIDFromBytes, implemented by OpenJDK here.

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.

Sculk Vibration Signal

Packet ID State Bound To Field Name Field Type Notes
0x05 Play Client Source Position Position Source position for the vibration.
Destination Identifier Identifier Identifier of the destination codec type.
Destination Varies Vanilla default destinations are a block position encoded as a Position for "block" or an entity id encoded as a VarInt for "entity".
Arrival Ticks VarInt Ticks for the signal to arrive at the destination.

This packet shows a permanent particle.

Entity Animation (clientbound)

Sent whenever an entity should change animation.

Packet ID State Bound To Field Name Field Type Notes
0x06 Play Client Entity ID VarInt Player ID.
Animation Unsigned Byte Animation ID (see below).

Animation can be one of the following values:

ID Animation
0 Swing main arm
1 Take damage
2 Leave bed
3 Swing offhand
4 Critical effect
5 Magic critical effect

Statistics

Sent as a response to Client Status 0x04 (id 1). Will only send the changed values if previously requested.

Packet ID State Bound To Field Name Field Type Notes
0x07 Play Client Count VarInt Number of elements in the following array.
Statistic Category ID Array VarInt See below.
Statistic ID VarInt See below.
Value VarInt The amount to set it to.

Categories (these are namespaced, but with : replaced with .):

Name ID Registry
minecraft.mined 0 Blocks
minecraft.crafted 1 Items
minecraft.used 2 Items
minecraft.broken 3 Items
minecraft.picked_up 4 Items
minecraft.dropped 5 Items
minecraft.killed 6 Entities
minecraft.killed_by 7 Entities
minecraft.custom 8 Custom

Blocks, Items, and Entities use block (not block state), item, and entity ids.

Custom has the following (unit only matters for clients):

Name ID Unit
minecraft.leave_game 0 None
minecraft.play_one_minute 1 Time
minecraft.time_since_death 2 Time
minecraft.time_since_rest 3 Time
minecraft.sneak_time 4 Time
minecraft.walk_one_cm 5 Distance
minecraft.crouch_one_cm 6 Distance
minecraft.sprint_one_cm 7 Distance
minecraft.walk_on_water_one_cm 8 Distance
minecraft.fall_one_cm 9 Distance
minecraft.climb_one_cm 10 Distance
minecraft.fly_one_cm 11 Distance
minecraft.walk_under_water_one_cm 12 Distance
minecraft.minecart_one_cm 13 Distance
minecraft.boat_one_cm 14 Distance
minecraft.pig_one_cm 15 Distance
minecraft.horse_one_cm 16 Distance
minecraft.aviate_one_cm 17 Distance
minecraft.swim_one_cm 18 Distance
minecraft.strider_one_cm 19 Distance
minecraft.jump 20 None
minecraft.drop 21 None
minecraft.damage_dealt 22 Damage
minecraft.damage_dealt_absorbed 23 Damage
minecraft.damage_dealt_resisted 24 Damage
minecraft.damage_taken 25 Damage
minecraft.damage_blocked_by_shield 26 Damage
minecraft.damage_absorbed 27 Damage
minecraft.damage_resisted 28 Damage
minecraft.deaths 29 None
minecraft.mob_kills 30 None
minecraft.animals_bred 31 None
minecraft.player_kills 32 None
minecraft.fish_caught 33 None
minecraft.talked_to_villager 34 None
minecraft.traded_with_villager 35 None
minecraft.eat_cake_slice 36 None
minecraft.fill_cauldron 37 None
minecraft.use_cauldron 38 None
minecraft.clean_armor 39 None
minecraft.clean_banner 40 None
minecraft.clean_shulker_box 41 None
minecraft.interact_with_brewingstand 42 None
minecraft.interact_with_beacon 43 None
minecraft.inspect_dropper 44 None
minecraft.inspect_hopper 45 None
minecraft.inspect_dispenser 46 None
minecraft.play_noteblock 47 None
minecraft.tune_noteblock 48 None
minecraft.pot_flower 49 None
minecraft.trigger_trapped_chest 50 None
minecraft.open_enderchest 51 None
minecraft.enchant_item 52 None
minecraft.play_record 53 None
minecraft.interact_with_furnace 54 None
minecraft.interact_with_crafting_table 55 None
minecraft.open_chest 56 None
minecraft.sleep_in_bed 57 None
minecraft.open_shulker_box 58 None
minecraft.open_barrel 59 None
minecraft.interact_with_blast_furnace 60 None
minecraft.interact_with_smoker 61 None
minecraft.interact_with_lectern 62 None
minecraft.interact_with_campfire 63 None
minecraft.interact_with_cartography_table 64 None
minecraft.interact_with_loom 65 None
minecraft.interact_with_stonecutter 66 None
minecraft.bell_ring 67 None
minecraft.raid_trigger 68 None
minecraft.raid_win 69 None
minecraft.interact_with_anvil 70 None
minecraft.interact_with_grindstone 71 None
minecraft.target_hit 72 None
minecraft.interact_with_smithing_table 73 None

Units:

  • None: just a normal number (formatted with 0 decimal places)
  • Damage: value is 10 times the normal amount
  • Distance: a distance in centimeters (hundredths of blocks)
  • Time: a time span in ticks

Acknowledge Player Digging

Packet ID State Bound To Field Name Field Type Notes
0x08 Play Client Location Position Position where the digging was happening.
Block VarInt Block state ID of the block that should be at that position now.
Status VarInt enum Same as Player Digging. Only Started digging (0), Cancelled digging (1), and Finished digging (2) are used.
Successful Boolean True if the digging succeeded; false if the client should undo any changes it made locally.

Block Break Animation

0–9 are the displayable destroy stages and each other number means that there is no animation on this coordinate.

Block break animations can still be applied on air; the animation will remain visible although there is no block being broken. However, if this is applied to a transparent block, odd graphical effects may happen, including water losing its transparency. (An effect similar to this can be seen in normal gameplay when breaking ice blocks)

If you need to display several break animations at the same time you have to give each of them a unique Entity ID. The entity ID does not need to correspond to an actual entity on the client. It is valid to use a randomly generated number.

Packet ID State Bound To Field Name Field Type Notes
0x09 Play Client Entity ID VarInt Entity ID of the entity breaking the block.
Location Position Block Position.
Destroy Stage Byte 0–9 to set it, any other value to remove it.

Block Entity Data

Sets the block entity associated with the block at the given location.

Packet ID State Bound To Field Name Field Type Notes
0x0A Play Client Location Position
Type VarInt The type of the block entity
NBT Data NBT Tag Data to set. May be a TAG_END (0), in which case the block entity at the given location is removed (though this is not required since the client will remove the block entity automatically on chunk unload or block removal).

Action field:

  • 1: Set data of a mob spawner (everything except for SpawnPotentials: current delay, min/max delay, mob to be spawned, spawn count, spawn range, etc.)
  • 2: Set command block text (command and last execution status)
  • 3: Set the level, primary, and secondary powers of a beacon
  • 4: Set rotation and skin of mob head
  • 5: Declare a conduit
  • 6: Set base color and patterns on a banner
  • 7: Set the data for a Structure tile entity
  • 8: Set the destination for a end gateway
  • 9: Set the text on a sign
  • 10: Unused
  • 11: Declare a bed
  • 12: Set data of a jigsaw block
  • 13: Set items in a campfire
  • 14: Beehive information

Block Action

This packet is used for a number of actions and animations performed by blocks, usually non-persistent.

See Block Actions for a list of values.

Warning.png This packet uses a block ID, not a block state.

Packet ID State Bound To Field Name Field Type Notes
0x0B Play Client Location Position Block coordinates.
Action ID (Byte 1) Unsigned Byte Varies depending on block — see Block Actions.
Action Param (Byte 2) Unsigned Byte Varies depending on block — see Block Actions.
Block Type VarInt The block type ID for the block. This must match the block at the given coordinates.

Block Change

Fired whenever a block is changed within the render distance.

Warning.png Changing a block in a chunk that is not loaded is not a stable action. The Notchian client currently uses a shared empty chunk which is modified for all block changes in unloaded chunks; while in 1.9 this chunk never renders in older versions the changed block will appear in all copies of the empty chunk. Servers should avoid sending block changes in unloaded chunks and clients should ignore such packets.

Packet ID State Bound To Field Name Field Type Notes
0x0C Play Client Location Position Block Coordinates.
Block ID VarInt The new block state ID for the block as given in the global palette. See that section for more information.

Boss Bar

Packet ID State Bound To Field Name Field Type Notes
0x0D 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 a Notchian 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), 0x04: create fog (previously was also controlled by 0x02).
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

Server Difficulty

Changes the difficulty setting in the client's option menu

Packet ID State Bound To Field Name Field Type Notes
0x0E Play Client Difficulty Unsigned Byte 0: peaceful, 1: easy, 2: normal, 3: hard.
Difficulty locked? Boolean

Chat Message (clientbound)

Identifying the difference between Chat/System Message is important as it helps respect the user's chat visibility options. See processing chat for more info about these positions.

Packet ID State Bound To Field Name Field Type Notes
0x0F Play Client JSON Data Chat Limited to 262144 bytes.
Position Byte 0: chat (chat box), 1: system message (chat box), 2: game info (above hotbar).
Sender UUID Used by the Notchian client for the disableChat launch option. Setting both longs to 0 will always display the message regardless of the setting.

Clear Titles

Clear the client's current title information, with the option to also reset it.

Packet ID State Bound To Field Name Field Type Notes
0x10 Play Client Reset Boolean

Tab-Complete (clientbound)

The server responds with a list of auto-completions of the last word sent to it. In the case of regular chat, this is a player username. Command names and parameters are also supported. The client sorts these alphabetically before listing them.

Packet ID State Bound To Field Name Field Type Notes
0x11 Play Client
ID VarInt Transaction ID.
Start VarInt Start of the text to replace.
Length VarInt Length of the text to replace.
Count VarInt Number of elements in the following array.
Matches Match Array String (32767) One eligible value to insert, note that each command is sent separately instead of in a single string, hence the need for Count. Note that for instance this doesn't include a leading / on commands.
Has tooltip Boolean True if the following is present.
Tooltip Optional Chat Tooltip to display; only present if previous boolean is true.

Declare Commands

Lists all of the commands on the server, and how they are parsed.

This is a directed graph, with one root node. Each redirect or child node must refer only to nodes that have already been declared.

Packet ID State Bound To Field Name Field Type Notes
0x12 Play Client Count VarInt Number of elements in the following array.
Nodes Array of Node An array of nodes.
Root index VarInt Index of the root node in the previous array.

For more information on this packet, see the Command Data article.

Close Window (clientbound)

This packet is sent from the server to the client when a window is forcibly closed, such as when a chest is destroyed while it's open. The notchian client disregards the provided window ID and closes any active window.

Packet ID State Bound To Field Name Field Type Notes
0x13 Play Client Window ID Unsigned Byte This is the ID of the window that was closed. 0 for inventory.

Window Items

The inventory slots

Sent by the server when items in multiple slots (in a window) are added/removed. This includes the main inventory, equipped armour and crafting slots. This packet with Window ID set to "0" is sent during the player joining sequence to initialise the player's inventory.

Packet ID State Bound To Field Name Field Type Notes
0x14 Play Client Window ID Unsigned Byte The ID of window which items are being sent for. 0 for player inventory.
State ID VarInt See State ID
Count VarInt Number of elements in the following array.
Slot Data Array of Slot
Carried Item Slot Item held by player.

See inventory windows for further information about how slots are indexed.

Window Property

This packet is used to inform the client that part of a GUI window should be updated.

Packet ID State Bound To Field Name Field Type Notes
0x15 Play Client Window ID Unsigned Byte
Property Short The property to be updated, see below.
Value Short The new value for the property, see below.

The meaning of the Property field depends on the type of the window. The following table shows the known combinations of window type and property, and how the value is to be interpreted.

Window type Property Value
Furnace 0: Fire icon (fuel left) counting from fuel burn time down to 0 (in-game ticks)
1: Maximum fuel burn time fuel burn time or 0 (in-game ticks)
2: Progress arrow counting from 0 to maximum progress (in-game ticks)
3: Maximum progress always 200 on the notchian server
Enchantment Table 0: Level requirement for top enchantment slot The enchantment's xp level requirement
1: Level requirement for middle enchantment slot
2: Level requirement for bottom enchantment slot
3: The enchantment seed Used for drawing the enchantment names (in SGA) clientside. The same seed is used to calculate enchantments, but some of the data isn't sent to the client to prevent easily guessing the entire list (the seed value here is the regular seed bitwise and 0xFFFFFFF0).
4: Enchantment ID shown on mouse hover over top enchantment slot The enchantment id (set to -1 to hide it), see below for values
5: Enchantment ID shown on mouse hover over middle enchantment slot
6: Enchantment ID shown on mouse hover over bottom enchantment slot
7: Enchantment level shown on mouse hover over the top slot The enchantment level (1 = I, 2 = II, 6 = VI, etc.), or -1 if no enchant
8: Enchantment level shown on mouse hover over the middle slot
9: Enchantment level shown on mouse hover over the bottom slot
Beacon 0: Power level 0-4, controls what effect buttons are enabled
1: First potion effect Potion effect ID for the first effect, or -1 if no effect
2: Second potion effect Potion effect ID for the second effect, or -1 if no effect
Anvil 0: Repair cost The repair's cost in xp levels
Brewing Stand 0: Brew time 0 – 400, with 400 making the arrow empty, and 0 making the arrow full
1: Fuel time 0 - 20, with 0 making the arrow empty, and 20 making the arrow full
Stonecutter 0: Selected recipe The index of the selected recipe. -1 means none is selected.
Loom 0: Selected pattern The index of the selected pattern. 0 means none is selected, 0 is also the internal id of the "base" pattern.
Lectern 0: Page number The current page number, starting from 0.

For an enchanting table, the following numerical IDs are used:

Numerical ID Enchantment ID Enchantment Name
0 minecraft:protection Protection
1 minecraft:fire_protection Fire Protection
2 minecraft:feather_falling Feather Falling
3 minecraft:blast_protection Blast Protection
4 minecraft:projectile_protection Projectile Protection
5 minecraft:respiration Respiration
6 minecraft:aqua_affinity Aqua Affinity
7 minecraft:thorns Thorns
8 minecraft:depth_strider Depth Strider
9 minecraft:frost_walker Frost Walker
10 minecraft:binding_curse Curse of Binding
11 minecraft:soul_speed Soul Speed
12 minecraft:sharpness Sharpness
13 minecraft:smite Smite
14 minecraft:bane_of_arthropods Bane of Arthropods
15 minecraft:knockback Knockback
16 minecraft:fire_aspect Fire Aspect
17 minecraft:looting Looting
18 minecraft:sweeping Sweeping Edge
19 minecraft:efficiency Efficiency
20 minecraft:silk_touch Silk Touch
21 minecraft:unbreaking Unbreaking
22 minecraft:fortune Fortune
23 minecraft:power Power
24 minecraft:punch Punch
25 minecraft:flame Flame
26 minecraft:infinity Infinity
27 minecraft:luck_of_the_sea Luck of the Sea
28 minecraft:lure Lure
29 minecraft:loyalty Loyalty
30 minecraft:impaling Impaling
31 minecraft:riptide Riptide
32 minecraft:channeling Channeling
33 minecraft:multishot Multishot
34 minecraft:quick_charge Quick Charge
35 minecraft:piercing Piercing
36 minecraft:mending Mending
37 minecraft:vanishing_curse Curse of Vanishing

Set Slot

Sent by the server when an item in a slot (in a window) is added/removed.

Packet ID State Bound To Field Name Field Type Notes
0x16 Play Client Window ID Byte The window which is being updated. 0 for player inventory. Note that all known window types include the player inventory. This packet will only be sent for the currently opened window while the player is performing actions, even if it affects the player inventory. After the window is closed, a number of these packets are sent to update the player's inventory window (0).
State ID VarInt See State ID
Slot Short The slot that should be updated.
Slot Data Slot

To set the cursor (the item currently dragged with the mouse), use -1 as Window ID and as Slot.

This packet can only be used to edit the hotbar of the player's inventory if window ID is set to 0 (slots 36 through 44). If the window ID is set to -2, then any slot in the inventory can be used but no add item animation will be played.

Set Cooldown

Applies a cooldown period to all items with the given type. Used by the Notchian server with enderpearls. This packet should be sent when the cooldown starts and also when the cooldown ends (to compensate for lag), although the client will end the cooldown automatically. Can be applied to any item, note that interactions still get sent to the server with the item but the client does not play the animation nor attempt to predict results (i.e block placing).

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

Plugin Message (clientbound)

Main article: Plugin channels

Mods and plugins can use this to send their data. Minecraft itself uses several plugin channels. These internal channels are in the minecraft namespace.

More documentation on this: https://dinnerbone.com/blog/2012/01/13/minecraft-plugin-channels-messaging/

Packet ID State Bound To Field Name Field Type Notes
0x18 Play Client Channel Identifier Name of the plugin channel used to send the data.
Data Byte Array Any data, depending on the channel. minecraft: channels are documented here. The length of this array must be inferred from the packet length.

Named Sound Effect

See also: #Sound Effect

Used to play a sound effect on the client. Custom sounds may be added by resource packs.

Packet ID State Bound To Field Name Field Type Notes
0x19 Play Client Sound Name Identifier All sound effect names as of 1.16.5 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 (fixed-point number with only 3 bits dedicated to the fractional part).
Effect Position Y Int Effect Y multiplied by 8 (fixed-point number with only 3 bits dedicated to the fractional part).
Effect Position Z Int Effect Z multiplied by 8 (fixed-point number with only 3 bits dedicated to the fractional part).
Volume Float 1 is 100%, can be more.
Pitch Float Float between 0.5 and 2.0 by Notchian clients.

Disconnect (play)

Sent by the server before it disconnects a client. The client assumes that the server has already closed the connection by the time the packet arrives.

Packet ID State Bound To Field Name Field Type Notes
0x1A Play Client Reason Chat Displayed to the client when the connection terminates.

Entity Status

Entity statuses generally trigger an animation for an entity. The available statuses vary by the entity's type (and are available to subclasses of that type as well).

Packet ID State Bound To Field Name Field Type Notes
0x1B Play Client Entity ID Int
Entity Status Byte Enum See Entity statuses for a list of which statuses are valid for each type of entity.

Explosion

Sent when an explosion occurs (creepers, TNT, and ghast fireballs).

Each block in Records is set to air. Coordinates for each axis in record is int(X) + record.x

Packet ID State Bound To Field Name Field Type Notes
0x1C Play Client X Float
Y Float
Z Float
Strength Float A strength greater than or equal to 2.0 spawns a minecraft:explosion_emitter particle, while a lesser strength spawns a minecraft:explosion particle.
Record Count VarInt Number of elements in the following array.
Records Array of (Byte, Byte, Byte) Each record is 3 signed bytes long; the 3 bytes are the XYZ (respectively) signed offsets of affected blocks.
Player Motion X Float X velocity of the player being pushed by the explosion.
Player Motion Y Float Y velocity of the player being pushed by the explosion.
Player Motion Z Float Z velocity of the player being pushed by the explosion.

Unload Chunk

Tells the client to unload a chunk column.

Packet ID State Bound To Field Name Field Type Notes
0x1D Play Client Chunk X Int Block coordinate divided by 16, rounded down.
Chunk Z Int Block coordinate divided by 16, rounded down.

It is legal to send this packet even if the given chunk is not currently loaded.

Change Game State

Used for a wide variety of game state things, from weather to bed use to gamemode to demo messages.

Packet ID State Bound To Field Name Field Type Notes
0x1E Play Client Reason Unsigned Byte See below.
Value Float Depends on Reason.

Reason codes:

Reason Effect Value
0 No respawn block available Note: Sends message 'block.minecraft.spawn.not_valid'(You have no home bed or charged respawn anchor, or it was obstructed) to the client.
1 End raining
2 Begin raining
3 Change gamemode 0: Survival, 1: Creative, 2: Adventure, 3: Spectator.
4 Win game 0: Just respawn player.
1: Roll the credits and respawn player.
Note that 1 is only sent by notchian server when player has not yet achieved advancement "The end?", else 0 is sent.
5 Demo event 0: Show welcome to demo screen
101: Tell movement controls
102: Tell jump control
103: Tell inventory control
104: Tell that the demo is over and print a message about how to take a screenshot.
6 Arrow hit player Note: Sent when any player is struck by an arrow.
7 Rain level change Note: Seems to change both skycolor and lightning.
Rain level starting from 0 to 1.
8 Thunder level change Note: Seems to change both skycolor and lightning (same as Rain level change, but doesn't start rain). It also requires rain to render by notchian client.
Thunder level starting from 0 to 1.
9 Play pufferfish sting sound.
10 Play elder guardian mob appearance (effect and sound).
11 Enable respawn screen 0: Enable respawn screen, 1: Immediately respawn (sent when the doImmediateRespawn gamerule changes).

Open Horse Window

This packet is used exclusively for opening the horse GUI. Open Window is used for all other GUIs. The client will not open the inventory if the Entity ID does not point to an horse-like animal.

Packet ID State Bound To Field Name Field Type Notes
0x1F Play Client Window ID Unsigned Byte
Slot count VarInt
Entity ID Integer

Initialize World Border

Packet ID State Bound To Field Name Field Type Notes
0x20 Play Client X Double
Z Double
Old Diameter Double Current length of a single side of the world border, in meters.
New Diameter Double Target length of a single side of the world border, in meters.
Speed VarLong Number of real-time milliseconds until New Diameter is reached. It appears that Notchian server does not sync world border speed to game ticks, so it gets out of sync with server lag. If the world border is not moving, this is set to 0.
Portal Teleport Boundary VarInt Resulting coordinates from a portal teleport are limited to ±value. Usually 29999984.
Warning Blocks VarInt In meters.
Warning Time VarInt In seconds as set by /worldborder warning time.

The Notchian client determines how solid to display the warning by comparing to whichever is higher, the warning distance or whichever is lower, the distance from the current diameter to the target diameter or the place the border will be after warningTime seconds. In pseudocode: 

distance = max(min(resizeSpeed * 1000 * warningTime, abs(targetDiameter - currentDiameter)), warningDistance);
if (playerDistance < distance) {
    warning = 1.0 - playerDistance / distance;
} else {
    warning = 0.0;
}

Keep Alive (clientbound)

The server will frequently send out a keep-alive, each containing a random ID. The client must respond with the same payload (see serverbound Keep Alive). If the client does not respond to them for over 30 seconds, the server kicks the client. Vice versa, if the server does not send any keep-alives for 20 seconds, the client will disconnect and yields a "Timed out" exception.

The Notchian server uses a system-dependent time in milliseconds to generate the keep alive ID value.

Packet ID State Bound To Field Name Field Type Notes
0x21 Play Client Keep Alive ID Long

Chunk Data And Update Light

Main article: Chunk Format
See also: #Unload Chunk
Huh.png The following information needs to be added to this page:
How do biomes work now? The biome change happened at the same time as the seed change, but it's not clear how/if biomes could be computed given that it's not the actual seed... (/r/mojira discussion which notes that it seems to be some kind of interpolation, and 3D biomes are only used in the nether)

The server only sends skylight information for chunk pillars in the Overworld, it's up to the client to know in which dimension the player is currently located. You can also infer this information from the primary bitmask and the amount of uncompressed bytes sent. This packet also sends all block entities in the chunk (though sending them is not required; it is still legal to send them with Block Entity Data later).

Packet ID State Bound To Field Name Field Type Notes
0x22 Play Client Chunk X Int Chunk coordinate (block coordinate divided by 16, rounded down)
Chunk Z Int Chunk coordinate (block coordinate divided by 16, rounded down)
Heightmaps NBT Compound containing one long array named MOTION_BLOCKING, which is a heightmap for the highest solid block at each position in the chunk (as a compacted long array with 256 entries, with the number of bits per entry varying depending on the world's height, defined by the formula ceil(log2(height + 1))). The Notchian server also adds a WORLD_SURFACE long array, the purpose of which is unknown, but it's not required for the chunk to be accepted.
Size VarInt Size of Data in bytes
Data Byte array See data structure in Chunk Format
Number of block entities VarInt Number of elements in the following array
Block Entity Packed XZ Array Byte The packed section coordinates, calculated from ((blockX & 15) << 4) | (blockZ & 15)
Y Short The height relative to the world
Type VarInt The type of block entity
Data NBT The block entity's data, without the X, Y, and Z values
Trust Edges Boolean If edges should be trusted for light updates.
Sky Light Mask BitSet BitSet containing bits for each section in the world + 2. Each set bit indicates that the corresponding 16×16×16 chunk section has data in the Sky Light array below. The least significant bit is for blocks 16 blocks to 1 block below the min world height (one section below the world), while the most significant bit covers blocks 1 to 16 blocks above the max world height (one section above the world).
Block Light Mask BitSet BitSet containing bits for each section in the world + 2. Each set bit indicates that the corresponding 16×16×16 chunk section has data in the Block Light array below. The order of bits is the same as in Sky Light Mask.
Empty Sky Light Mask BitSet BitSet containing bits for each section in the world + 2. Each set bit indicates that the corresponding 16×16×16 chunk section has all zeros for its Sky Light data. The order of bits is the same as in Sky Light Mask.
Empty Block Light Mask BitSet BitSet containing bits for each section in the world + 2. Each set bit indicates that the corresponding 16×16×16 chunk section has all zeros for its Block Light data. The order of bits is the same as in Sky Light Mask.
Sky Light array count VarInt Number of entries in the following array; should match the number of bits set in Sky Light Mask
Sky Light arrays Length Array VarInt Length of the following array in bytes (always 2048)
Sky Light array Array of 2048 bytes There is 1 array for each bit set to true in the sky light mask, starting with the lowest value. Half a byte per light value.
Block Light array count VarInt Number of entries in the following array; should match the number of bits set in Block Light Mask
Block Light arrays Length Array VarInt Length of the following array in bytes (always 2048)
Block Light array Array of 2048 bytes There is 1 array for each bit set to true in the block light mask, starting with the lowest value. Half a byte per light value.

Note that the Notchian client requires an Update View Position packet when it crosses a chunk border, otherwise it'll only display render distance + 2 chunks around the chunk it spawned in.

The compacted array format has been adjusted so that individual entries no longer span across multiple longs, affecting the main data array and heightmaps.

New format, 5 bits per block, containing the following references to blocks in a palette (not shown): 122344566480743131516914101202

0020863148418841 0000000000100000100001100011000101001000010000011000100001000001
01018A7260F68C87 0000000100000001100010100111001001100000111101101000110010000111

Effect

Sent when a client is to play a sound or particle effect.

By default, the Minecraft client adjusts the volume of sound effects based on distance. The final boolean field is used to disable this, and instead the effect is played from 2 blocks away in the correct direction. Currently this is only used for effect 1023 (wither spawn), effect 1028 (enderdragon death), and effect 1038 (end portal opening); it is ignored on other effects.

Packet ID State Bound To Field Name Field Type Notes
0x23 Play Client Effect ID Int The ID of the effect, see below.
Location Position The location of the effect.
Data Int Extra data for certain effects, see below.
Disable Relative Volume Boolean See above.

Effect IDs:

ID Name Data
Sound
1000 Dispenser dispenses
1001 Dispenser fails to dispense
1002 Dispenser shoots
1003 Ender eye launched
1004 Firework shot
1005 Iron door opened
1006 Wooden door opened
1007 Wooden trapdoor opened
1008 Fence gate opened
1009 Fire extinguished
1010 Play record Special case, see below for more info.
1011 Iron door closed
1012 Wooden door closed
1013 Wooden trapdoor closed
1014 Fence gate closed
1015 Ghast warns
1016 Ghast shoots
1017 Enderdragon shoots
1018 Blaze shoots
1019 Zombie attacks wood door
1020 Zombie attacks iron door
1021 Zombie breaks wood door
1022 Wither breaks block
1023 Wither spawned
1024 Wither shoots
1025 Bat takes off
1026 Zombie infects
1027 Zombie villager converted
1028 Ender dragon death
1029 Anvil destroyed
1030 Anvil used
1031 Anvil landed
1032 Portal travel
1033 Chorus flower grown
1034 Chorus flower died
1035 Brewing stand brewed
1036 Iron trapdoor opened
1037 Iron trapdoor closed
1038 End portal created in overworld
1039 Phantom bites
1040 Zombie converts to drowned
1041 Husk converts to zombie by drowning
1042 Grindstone used
1043 Book page turned
Particle
1500 Composter composts
1501 Lava converts block (either water to stone, or removes existing blocks such as torches)
1502 Redstone torch burns out
1503 Ender eye placed
2000 Spawns 10 smoke particles, e.g. from a fire Direction, see below.
2001 Block break + block break sound Block state, as an index into the global palette.
2002 Splash potion. Particle effect + glass break sound. RGB color as an integer (e.g. 8364543 for #7FA1FF).
2003 Eye of Ender entity break animation — particles and sound
2004 Mob spawn particle effect: smoke + flames
2005 Bonemeal particles How many particles to spawn (if set to 0, 15 are spawned).
2006 Dragon breath
2007 Instant splash potion. Particle effect + glass break sound. RGB color as an integer (e.g. 8364543 for #7FA1FF).
2008 Ender dragon destroys block
2009 Wet sponge vaporizes in nether
3000 End gateway spawn
3001 Enderdragon growl
3002 Electric spark
3003 Copper apply wax
3004 Copper remove wax
3005 Copper scrape oxidation

Smoke directions:

ID Direction
0 Down
1 Up
2 North
3 South
4 West
5 East

Play record: This is actually a special case within this packet. You can start/stop a record at a specific location. Use a valid Record ID to start a record (or overwrite a currently playing one), any other value will stop the record. See Data Generators for information on item IDs.

Particle

Displays the named particle

Packet ID State Bound To Field Name Field Type Notes
0x24 Play Client Particle ID Int The particle ID listed in the particle data type.
Long Distance Boolean If true, particle distance increases from 256 to 65536.
X Double X position of the particle.
Y Double Y position of the particle.
Z Double Z position of the particle.
Offset X Float This is added to the X position after being multiplied by random.nextGaussian().
Offset Y Float This is added to the Y position after being multiplied by random.nextGaussian().
Offset Z Float This is added to the Z position after being multiplied by random.nextGaussian().
Particle Data Float The data of each particle.
Particle Count Int The number of particles to create.
Data Varies The variable data listed in the particle data type.

Update Light

Updates light levels for a chunk. See Light for information on how lighting works in Minecraft.

Packet ID State Bound To Field Name Field Type Notes
0x25 Play Client Chunk X VarInt Chunk coordinate (block coordinate divided by 16, rounded down)
Chunk Z VarInt Chunk coordinate (block coordinate divided by 16, rounded down)
Trust Edges Boolean If edges should be trusted for light updates.
Sky Light Mask BitSet BitSet containing bits for each section in the world + 2. Each set bit indicates that the corresponding 16×16×16 chunk section has data in the Sky Light array below. The least significant bit is for blocks 16 blocks to 1 block below the min world height (one section below the world), while the most significant bit covers blocks 1 to 16 blocks above the max world height (one section above the world).
Block Light Mask BitSet BitSet containing bits for each section in the world + 2. Each set bit indicates that the corresponding 16×16×16 chunk section has data in the Block Light array below. The order of bits is the same as in Sky Light Mask.
Empty Sky Light Mask BitSet BitSet containing bits for each section in the world + 2. Each set bit indicates that the corresponding 16×16×16 chunk section has all zeros for its Sky Light data. The order of bits is the same as in Sky Light Mask.
Empty Block Light Mask BitSet BitSet containing bits for each section in the world + 2. Each set bit indicates that the corresponding 16×16×16 chunk section has all zeros for its Block Light data. The order of bits is the same as in Sky Light Mask.
Sky Light array count VarInt Number of entries in the following array; should match the number of bits set in Sky Light Mask
Sky Light arrays Length Array VarInt Length of the following array in bytes (always 2048)
Sky Light array Array of 2048 bytes There is 1 array for each bit set to true in the sky light mask, starting with the lowest value. Half a byte per light value.
Block Light array count VarInt Number of entries in the following array; should match the number of bits set in Block Light Mask
Block Light arrays Length Array VarInt Length of the following array in bytes (always 2048)
Block Light array Array of 2048 bytes There is 1 array for each bit set to true in the block light mask, starting with the lowest value. Half a byte per light value.

A bit will never be set in both the block light mask and the empty block light mask, though it may be present in neither of them (if the block light does not need to be updated for the corresponding chunk section). The same applies to the sky light mask and the empty sky light mask.

Join Game

See Protocol Encryption for information on logging in.

Packet ID State Bound To Field Name Field Type Notes
0x26 Play Client Entity ID Int The player's Entity ID (EID).
Is hardcore Boolean
Gamemode Unsigned Byte 0: Survival, 1: Creative, 2: Adventure, 3: Spectator.
Previous Gamemode Byte 0: survival, 1: creative, 2: adventure, 3: spectator. The hardcore flag is not included. The previous gamemode. Defaults to -1 if there is no previous gamemode. (More information needed)
World Count VarInt Size of the following array.
World Names Array of Identifier Identifiers for all worlds on the server.
Dimension Codec NBT Tag Compound The full extent of these is still unknown, but the tag represents a dimension and biome registry. See below for the vanilla default.
Dimension NBT Tag Compound Valid dimensions are defined per dimension registry sent before this. The structure of this tag is a dimension type (see below).
World Name Identifier Name of the world being spawned into.
Hashed seed Long First 8 bytes of the SHA-256 hash of the world's seed. Used client side for biome noise
Max Players VarInt Was once used by the client to draw the player list, but now is ignored.
View Distance VarInt Render distance (2-32).
Simulation Distance VarInt The distance that the client will process specific things, such as entities.
Reduced Debug Info Boolean If true, a Notchian client shows reduced information on the debug screen. For servers in development, this should almost always be false.
Enable respawn screen Boolean Set to false when the doImmediateRespawn gamerule is true.
Is Debug Boolean True if the world is a debug mode world; debug mode worlds cannot be modified and have predefined blocks.
Is Flat Boolean True if the world is a superflat world; flat worlds have different void fog and a horizon at y=0 instead of y=63.


The Dimension Codec NBT Tag Compound (Default value in SNBT) includes two registries: "minecraft:dimension_type" and "minecraft:worldgen/biome".

Name Type Notes
minecraft:dimension_type TAG_Compound The dimension type registry (see below).
minecraft:worldgen/biome TAG_Compound The biome registry (see below).

Dimension type registry:

Name Type Notes
type TAG_String The name of the registry. Always "minecraft:dimension_type".
value TAG_List List of dimension types registry entries (see below).

Dimension type registry entry:

Name Type Notes
name TAG_String The name of the dimension type (for example, "minecraft:overworld").
id TAG_Int The protocol ID of the dimension (matches the index of the element in the registry list).
element TAG_Compound The dimension type (see below).

Dimension type:

Name Type Meaning Values
piglin_safe TAG_Byte Whether piglins shake and transform to zombified piglins. 1: true, 0: false.
natural TAG_Byte When false, compasses spin randomly. When true, nether portals can spawn zombified piglins. 1: true, 0: false.
ambient_light TAG_Float How much light the dimension has. 0.0 to 1.0.
fixed_time Optional TAG_Long If set, the time of the day is the specified value. If set, 0 to 24000.
infiniburn TAG_String A resource location defining what block tag to use for infiniburn. "" or minecraft resource "minecraft:...".
respawn_anchor_works TAG_Byte Whether players can charge and use respawn anchors. 1: true, 0: false.
has_skylight TAG_Byte Whether the dimension has skylight access or not. 1: true, 0: false.
bed_works TAG_Byte Whether players can use a bed to sleep. 1: true, 0: false.
effects TAG_String ? "minecraft:overworld", "minecraft:the_nether", "minecraft:the_end" or something else.
has_raids TAG_Byte Whether players with the Bad Omen effect can cause a raid. 1: true, 0: false.
min_y TAG_Int The minimum Y level.
height TAG_Int The maximum height.
logical_height TAG_Int The maximum height to which chorus fruits and nether portals can bring players within this dimension. 0-256.
coordinate_scale TAG_Float The multiplier applied to coordinates when traveling to the dimension. 0.00001 - 30000000.0
ultrawarm TAG_Byte Whether the dimensions behaves like the nether (water evaporates and sponges dry) or not. Also causes lava to spread thinner. 1: true, 0: false.
has_ceiling TAG_Byte Whether the dimension has a bedrock ceiling or not. When true, causes lava to spread faster. 1: true, 0: false.

Biome registry:

Name Type Notes
type TAG_String The name of the registry. Always "minecraft:worldgen/biome".
value TAG_List List of biome registry entries (see below).

Biome registry entry:

Name Type Notes
name TAG_String The name of the biome (for example, "minecraft:ocean").
id TAG_Int The protocol ID of the biome (matches the index of the element in the registry list).
element TAG_Compound The biome properties (see below).

Biome properties:

Name Type Meaning Values
precipitation TAG_String The type of precipitation in the biome. "rain", "snow", or "none".
depth TAG_Float The depth factor of the biome. The default values vary between 1.5 and -1.8.
temperature TAG_Float The temperature factor of the biome. The default values vary between 2.0 and -0.5.
scale TAG_Float ? The default values vary between 1.225 and 0.0.
downfall TAG_Float ? The default values vary between 1.0 and 0.0.
category TAG_String The category of the biome. Known values are "ocean", "plains", "desert", "forest", "extreme_hills", "taiga", "swamp", "river", "nether", "the_end", "icy", "mushroom", "beach", "jungle", "mesa", "savanna", and "none".
temperature_modifier Optional TAG_String ? The only known value is "frozen".
effects sky_color TAG_Compound TAG_Int The color of the sky. Example: 8364543, which is #7FA1FF in RGB.
water_fog_color TAG_Int Possibly the tint color when swimming. Example: 8364543, which is #7FA1FF in RGB.
fog_color TAG_Int Possibly the color of the fog effect when looking past the view distance. Example: 8364543, which is #7FA1FF in RGB.
water_color TAG_Int The tint color of the water blocks. Example: 8364543, which is #7FA1FF in RGB.
foliage_color Optional TAG_Int The tint color of the grass. Example: 8364543, which is #7FA1FF in RGB.
grass_color Optional TAG_Int ? Example: 8364543, which is #7FA1FF in RGB.
grass_color_modifier Optional TAG_String Unknown, likely affects foliage color. If set, known values are "swamp" and "dark_forest".
music Optional TAG_Compound Music properties for the biome. If present, contains the fields: replace_current_music (TAG_Byte), sound (TAG_String), max_delay (TAG_Int), min_delay (TAG_Int).
ambient_sound Optional TAG_String Ambient soundtrack. If present, the ID of a soundtrack. Example: "minecraft:ambient.basalt_deltas.loop".
additions_sound Optional TAG_Compound Additional ambient sound that plays randomly. If present, contains the fields: sound (TAG_String), tick_chance (TAG_Double).
mood_sound Optional TAG_Compound Additional ambient sound that plays at an interval. If present, contains the fields: sound (TAG_String), tick_delay (TAG_Int), offset (TAG_Double), block_search_extent (TAG_Int).
particle probability Optional TAG_Compound TAG_FLOAT Particles that appear randomly in the biome. Possibly the probability of spawning the particle. ?
options TAG_COMPOUND The properties of the particle to spawn. Contains the field "type" (TAG_String), which identifies the particle type.

Map Data

Updates a rectangular area on a map item.

Packet ID State Bound To Field Name Field Type Notes
0x27 Play Client Map ID VarInt 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)
Locked Boolean True if the map has been locked in a cartography table
Tracking Position Boolean Specifies whether player and item frame icons are shown
Icon Count VarInt Number of elements in the following array. Only present if "Tracking Position" is true.
Icon Type Array VarInt enum See below
X Byte Map coordinates: -128 for furthest left, +127 for furthest right
Z Byte Map coordinates: -128 for highest, +127 for lowest
Direction Byte 0-15
Has Display Name Boolean
Display Name Optional Chat Only present if previous Boolean is true
Columns Unsigned Byte Number of columns updated
Rows Optional Unsigned 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 Unsigned Byte Only if Columns is more than 0; see Map item format

For icons, a direction of 0 is a vertical icon and increments by 22.5° (360/16).

Types are based off of rows and columns in map_icons.png:

Icon type Result
0 White arrow (players)
1 Green arrow (item frames)
2 Red arrow
3 Blue arrow
4 White cross
5 Red pointer
6 White circle (off-map players)
7 Small white circle (far-off-map players)
8 Mansion
9 Temple
10 White Banner
11 Orange Banner
12 Magenta Banner
13 Light Blue Banner
14 Yellow Banner
15 Lime Banner
16 Pink Banner
17 Gray Banner
18 Light Gray Banner
19 Cyan Banner
20 Purple Banner
21 Blue Banner
22 Brown Banner
23 Green Banner
24 Red Banner
25 Black Banner
26 Treasure marker

Trade List

The list of trades a villager NPC is offering.

Packet ID State Bound To Field Name Field Type Notes
0x28 Play Client
Window ID VarInt The ID of the window that is open; this is an int rather than a byte.
Size Byte The number of trades in the following array.
Trades Input item 1 Array Slot The first item the player has to supply for this villager trade. The count of the item stack is the default "price" of this trade.
Output item Slot The item the player will receive from this villager trade.
Has second item Boolean Whether there is a second item.
Input item 2 Optional Slot The second item the player has to supply for this villager trade; only present if has a second item is true.
Trade disabled Boolean True if the trade is disabled; false if the trade is enabled.
Number of trade uses Integer Number of times the trade has been used so far. If equal to the maximum number of trades, the client will display a red X.
Maximum number of trade uses Integer Number of times this trade can be used before it's exhausted.
XP Integer Amount of XP both the player and the villager will earn each time the trade is used.
Special Price Integer Can be zero or negative. The number is added to the price when an item is discounted due to player reputation or other effects.
Price Multiplier Float Can be low (0.05) or high (0.2). Determines how much demand, player reputation, and temporary effects will adjust the price.
Demand Integer Can be zero or a positive number. Causes the price to increase when a trade is used repeatedly.
Villager level VarInt Appears on the trade GUI; meaning comes from the translation key merchant.level. + level.

1: Novice, 2: Apprentice, 3: Journeyman, 4: Expert, 5: Master.

Experience VarInt Total experience for this villager (always 0 for the wandering trader).
Is regular villager Boolean True if this is a regular villager; false for the wandering trader. When false, hides the villager level and some other GUI elements.
Can restock Boolean True for regular villagers and false for the wandering trader. If true, the "Villagers restock up to two times per day." message is displayed when hovering over disabled trades.

Modifiers can increase or decrease the number of items for the first input slot. The second input slot and the output slot never change the nubmer of items. The number of items may never be less than 1, and never more than the stack size. If special price and demand are both zero, only the default price is displayed. If either is non-zero, then the adjusted price is displayed next to the crossed-out default price. The adjusted prices is calculated as follows:

Adjusted price = default price + floor(default price x multiplier x demand) + special price

The merchant UI, for reference

Entity Position

This packet is sent by the server when an entity moves less then 8 blocks; if an entity moves more than 8 blocks Entity Teleport should be sent instead.

This packet allows at most 8 blocks movement in any direction, because short range is from -32768 to 32767. And 32768 / (128 * 32) = 8.

Packet ID State Bound To Field Name Field Type Notes
0x29 Play Client Entity ID VarInt
Delta X Short Change in X position as (currentX * 32 - prevX * 32) * 128.
Delta Y Short Change in Y position as (currentY * 32 - prevY * 32) * 128.
Delta Z Short Change in Z position as (currentZ * 32 - prevZ * 32) * 128.
On Ground Boolean

Entity Position and Rotation

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 8 blocks movement in any direction. (-32768 / (32 * 128) == -8)

Packet ID State Bound To Field Name Field Type Notes
0x2A Play Client Entity ID VarInt
Delta X Short Change in X position as (currentX * 32 - prevX * 32) * 128.
Delta Y Short Change in Y position as (currentY * 32 - prevY * 32) * 128.
Delta Z Short Change in Z position as (currentZ * 32 - prevZ * 32) * 128.
Yaw Angle New angle, not a delta.
Pitch Angle New angle, not a delta.
On Ground Boolean

Entity Rotation

This packet is sent by the server when an entity rotates.

Packet ID State Bound To Field Name Field Type Notes
0x2B Play Client Entity ID VarInt
Yaw Angle New angle, not a delta.
Pitch Angle New angle, not a delta.
On Ground Boolean

Vehicle Move (clientbound)

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

Packet ID State Bound To Field Name Field Type Notes
0x2C 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.

Open Book

Sent when a player right clicks with a signed book. This tells the client to open the book GUI.

Packet ID State Bound To Field Name Field Type Notes
0x2D Play Client Hand VarInt enum 0: Main hand, 1: Off hand .

Open Window

This is sent to the client when it should open an inventory, such as a chest, workbench, or furnace. This message is not sent anywhere for clients opening their own inventory. Resending this packet with already existing window id, will update the window title and window type without closing the window. For horses, use Open Horse Window.

Packet ID State Bound To Field Name Field Type Notes
0x2E Play Client Window ID VarInt A unique id number for the window to be displayed. Notchian server implementation is a counter, starting at 1.
Window Type VarInt The window type to use for display. Contained in the minecraft:menu registry; see Inventory for the different values.
Window Title Chat The title of the window.

Open Sign Editor

Sent when the client has placed a sign and is allowed to send Update Sign. There must already be a sign at the given location (which the client does not do automatically) - send a Block Change first.

Packet ID State Bound To Field Name Field Type Notes
0x2F Play Client Location Position

Ping

Packet is not used by the Notchian server. When sent to the client, client responds with a Pong packet with the same id.

Packet ID State Bound To Field Name Field Type Notes
0x30 Play Client ID Int

Craft Recipe Response

Response to the serverbound packet (Craft Recipe Request), with the same recipe ID. Appears to be used to notify the UI.

Packet ID State Bound To Field Name Field Type Notes
0x31 Play Client Window ID Byte
Recipe Identifier A recipe ID.

Player Abilities (clientbound)

The latter 2 floats are used to indicate the field of view and flying speed respectively, while the first byte is used to determine the value of 4 booleans.

Packet ID State Bound To Field Name Field Type Notes
0x32 Play Client Flags Byte Bit field, see below.
Flying Speed Float 0.05 by default.
Field of View Modifier Float Modifies the field of view, like a speed potion. A Notchian server will use the same value as the movement speed sent in the Entity Properties packet, which defaults to 0.1 for players.

About the flags:

Field Bit
Invulnerable 0x01
Flying 0x02
Allow Flying 0x04
Creative Mode (Instant Break) 0x08

End Combat Event

Unused by the Notchain client. This data was once used for twitch.tv metadata circa 1.8.f

Packet ID State Bound To Field Name Field Type Notes
0x33 Play Client Duration VarInt Length of the combat in ticks.
Entity ID Int ID of the primary opponent of the ended combat, or -1 if there is no obvious primary opponent.

Enter Combat Event

Unused by the Notchain client. This data was once used for twitch.tv metadata circa 1.8.

Packet ID State Bound To Field Name Field Type Notes
0x34 Play Client no fields

Death Combat Event

Used to send a respawn screen.

Packet ID State Bound To Field Name Field Type Notes
0x35 Play Client Player ID VarInt Entity ID of the player that died (should match the client's entity ID).
Entity ID Int The killer entity's ID, or -1 if there is no obvious killer.
Message Chat The death message.

Player Info

Sent by the server to update the user list (<tab> in the client).

Packet ID State Bound To Field Name Field Type Notes
0x36 Play Client Action VarInt Determines the rest of the Player format after the UUID.
Number Of Players VarInt Number of elements in the following array.
Player UUID Array UUID
Action Field Name
0: add player Name String (16)
Number Of Properties VarInt Number of elements in the following array.
Property Name Array String (32767)
Value String (32767)
Is Signed Boolean
Signature Optional String (32767) Only if Is Signed is true.
Gamemode VarInt
Ping VarInt Measured in milliseconds.
Has Display Name Boolean
Display Name Optional Chat Only if Has Display Name is true.
1: update gamemode Gamemode VarInt
2: update latency Ping VarInt Measured in milliseconds.
3: update display name Has Display Name Boolean
Display Name Optional Chat Only send if Has Display Name is true.
4: remove player no fields no fields

The Property field looks as in the response of Mojang API#UUID -> Profile + Skin/Cape, except of course using the protocol format instead of JSON. That is, each player will usually have one property with Name “textures” and Value being a base64-encoded JSON string as documented at Mojang API#UUID -> Profile + Skin/Cape. An empty properties array is also acceptable, and will cause clients to display the player with one of the two default skins depending on UUID.

Ping values correspond with icons in the following way:

  • A ping that negative (i.e. not known to the server yet) will result in the no connection icon.
  • A ping under 150 milliseconds will result in 5 bars
  • A ping under 300 milliseconds will result in 4 bars
  • A ping under 600 milliseconds will result in 3 bars
  • A ping under 1000 milliseconds (1 second) will result in 2 bars
  • A ping greater than or equal to 1 second will result in 1 bar.

Face Player

Used to rotate the client player to face the given location or entity (for /teleport [<targets>] <x> <y> <z> facing).

Packet ID State Bound To Field Name Field Type Notes
0x37 Play Client
Feet/eyes VarInt enum Values are feet=0, eyes=1. If set to eyes, aims using the head position; otherwise aims using the feet position.
Target x Double x coordinate of the point to face towards.
Target y Double y coordinate of the point to face towards.
Target z Double z coordinate of the point to face towards.
Is entity Boolean If true, additional information about an entity is provided.
Entity ID Optional VarInt Only if is entity is true — the entity to face towards.
Entity feet/eyes Optional VarInt enum Whether to look at the entity's eyes or feet. Same values and meanings as before, just for the entity's head/feet.

If the entity given by entity ID cannot be found, this packet should be treated as if is entity was false.

Player Position And Look (clientbound)

Updates the player's position on the server. This packet will also close the “Downloading Terrain” screen when joining/respawning.

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.

Packet ID State Bound To Field Name Field Type Notes
0x38 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.
Dismount Vehicle Boolean True if the player should dismount their vehicle.

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

Unlock Recipes

Packet ID State Bound To Field Name Field Type Notes
0x39 Play Client
Action VarInt 0: init, 1: add, 2: remove.
Crafting Recipe Book Open Boolean If true, then the crafting recipe book will be open when the player opens its inventory.
Crafting Recipe Book Filter Active Boolean If true, then the filtering option is active when the players opens its inventory.
Smelting Recipe Book Open Boolean If true, then the smelting recipe book will be open when the player opens its inventory.
Smelting Recipe Book Filter Active Boolean If true, then the filtering option is active when the players opens its inventory.
Blast Furnace Recipe Book Open Boolean If true, then the blast furnace recipe book will be open when the player opens its inventory.
Blast Furnace Recipe Book Filter Active Boolean If true, then the filtering option is active when the players opens its inventory.
Smoker Recipe Book Open Boolean If true, then the smoker recipe book will be open when the player opens its inventory.
Smoker Recipe Book Filter Active Boolean If true, then the filtering option is active when the players opens its inventory.
Array size 1 VarInt Number of elements in the following array.
Recipe IDs Array of Identifier
Array size 2 Optional VarInt Number of elements in the following array, only present if mode is 0 (init).
Recipe IDs Optional Array of Identifier Only present if mode is 0 (init)

Action:

  • 0 (init) = All the recipes in list 1 will be tagged as displayed, and all the recipes in list 2 will be added to the recipe book. Recipes that aren't tagged will be shown in the notification.
  • 1 (add) = All the recipes in the list are added to the recipe book and their icons will be shown in the notification.
  • 2 (remove) = Remove all the recipes in the list. This allows them to be re-displayed when they are re-added.

Destroy Entities

Sent by the server when an entity is to be destroyed on the client.

Packet ID State Bound To Field Name Field Type Notes
0x3A Play Client Count VarInt Number of elements in the following array.
Entity IDs Array of VarInt The list of entities to destroy.

Remove Entity Effect

Packet ID State Bound To Field Name Field Type Notes
0x3B Play Client Entity ID VarInt
Effect ID Byte See this table.

Resource Pack Send

Packet ID State Bound To Field Name Field Type Notes
0x3C Play Client URL String (32767) The URL to the resource pack.
Hash String (40) A 40 character hexadecimal and lowercase SHA-1 hash of the resource pack file. (must be lower case in order to work)
If it's not a 40 character hexadecimal string, the client will not use it for hash verification and likely waste bandwidth — but it will still treat it as a unique id
Forced Boolean The notchian client will be forced to use the resource pack from the server. If they decline they will be kicked from the server.
Has Prompt Message Boolean true If the next field will be sent false otherwise. When false, this is the end of the packet
Prompt Message Optional Chat This is shown in the prompt making the client accept or decline the resource pack.

Respawn

To change the player's dimension (overworld/nether/end), send them a respawn packet with the appropriate dimension, followed by prechunks/chunks for the new dimension, and finally a position and look packet. You do not need to unload chunks, the client will do it automatically.

Packet ID State Bound To Field Name Field Type Notes
0x3D Play Client Dimension NBT Tag Compound Valid dimensions are defined per dimension registry sent in Join Game
World Name Identifier Name of the world being spawned into
Hashed seed Long First 8 bytes of the SHA-256 hash of the world's seed. Used client side for biome noise
Gamemode Unsigned Byte 0: survival, 1: creative, 2: adventure, 3: spectator. The hardcore flag is not included
Previous Gamemode Unsigned Byte 0: survival, 1: creative, 2: adventure, 3: spectator. The hardcore flag is not included. The previous gamemode. (More information needed)
Is Debug Boolean True if the world is a debug mode world; debug mode worlds cannot be modified and have predefined blocks.
Is Flat Boolean True if the world is a superflat world; flat worlds have different void fog and a horizon at y=0 instead of y=63.
Copy metadata Boolean If false, metadata is reset on the respawned player entity. Set to true for dimension changes (including the dimension change triggered by sending client status perform respawn to exit the end poem/credits), and false for normal respawns.
Huh.png The following information needs to be added to this page:
Does the new World Name field resolve this same-dimension issue?

Warning.png Avoid changing player's dimension to same dimension they were already in unless they are dead. If you change the dimension to one they are already in, weird bugs can occur, such as the player being unable to attack other players in new world (until they die and respawn).

If you must respawn a player in the same dimension without killing them, send two respawn packets, one to a different world and then another to the world you want. You do not need to complete the first respawn; it only matters that you send two packets.

Entity Head Look

Changes the direction an entity's head is facing.

While sending the Entity Look packet changes the vertical rotation of the head, sending this packet appears to be necessary to rotate the head horizontally.

Packet ID State Bound To Field Name Field Type Notes
0x3E Play Client Entity ID VarInt
Head Yaw Angle New angle, not a delta.

Multi Block Change

Fired whenever 2 or more blocks are changed within the same chunk on the same tick.

Warning.png Changing blocks in chunks not loaded by the client is unsafe (see note on Block Change).

Packet ID State Bound To Field Name Field Type Notes
0x3F Play Client Chunk section position Long Chunk section coordinate (encoded chunk x and z with each 22 bits, and section y with 20 bits, from left to right).
Boolean Always inverse the preceding Update Light packet's "Trust Edges" bool
Blocks array size VarInt Number of elements in the following array.
Blocks Array of VarLong Each entry is composed of the block state id, shifted left by 12, and the relative block position in the chunk section (4 bits for x, z, and y, from left to right).

Chunk section position is encoded: 

((sectionX & 0x3FFFFF) << 42) | (sectionY & 0xFFFFF) | ((sectionZ & 0x3FFFFF) << 20);

and decoded: 

sectionX = long >> 42;
sectionY = long << 44 >> 44;
sectionZ = long << 22 >> 42;

Blocks are encoded: 

blockStateId << 12 | (blockLocalX << 8 | blockLocalZ << 4 | blockLocalY)
//Uses the local position of the given block position relative to its respective chunk section

Select Advancement Tab

Sent by the server to indicate that the client should switch advancement tab. Sent either when the client switches tab in the GUI or when an advancement in another tab is made.

Packet ID State Bound To Field Name Field Type Notes
0x40 Play Client Has id Boolean Indicates if the next field is present.
Optional Identifier String (32767) See below.

The Identifier can be one of the following:

Optional Identifier
minecraft:story/root
minecraft:nether/root
minecraft:end/root
minecraft:adventure/root
minecraft:husbandry/root

If no or an invalid identifier is sent, the client will switch to the first tab in the GUI.

Action Bar

Packet ID State Bound To Field Name Field Type Notes
0x41 Play Client Action bar text Chat Displays a message above the hotbar (the same as position 2 in Chat Message (clientbound).

World Border Center

Packet ID State Bound To Field Name Field Type Notes
0x42 Play Client X Double
Z Double

World Border Lerp Size

Packet ID State Bound To Field Name Field Type Notes
0x43 Play Client Old Diameter Double Current length of a single side of the world border, in meters.
New Diameter Double Target length of a single side of the world border, in meters.
Speed VarLong Number of real-time milliseconds until New Diameter is reached. It appears that Notchian server does not sync world border speed to game ticks, so it gets out of sync with server lag. If the world border is not moving, this is set to 0.

World Border Size

Packet ID State Bound To Field Name Field Type Notes
0x44 Play Client Diameter Double Length of a single side of the world border, in meters.

World Border Warning Delay

Packet ID State Bound To Field Name Field Type Notes
0x45 Play Client Warning Time VarInt In seconds as set by /worldborder warning time.

World Border Warning Reach

Packet ID State Bound To Field Name Field Type Notes
0x46 Play Client Warning Blocks VarInt In meters.

Camera

Sets the entity that the player renders from. This is normally used when the player left-clicks an entity while in spectator mode.

The player's camera will move with the entity and look where it is looking. The entity is often another player, but can be any type of entity. The player is unable to move this entity (move packets will act as if they are coming from the other entity).

If the given entity is not loaded by the player, this packet is ignored. To return control to the player, send this packet with their entity ID.

The Notchian server resets this (sends it back to the default entity) whenever the spectated entity is killed or the player sneaks, but only if they were spectating an entity. It also sends this packet whenever the player switches out of spectator mode (even if they weren't spectating an entity).

Packet ID State Bound To Field Name Field Type Notes
0x47 Play Client Camera ID VarInt ID of the entity to set the client's camera to.

The notchian client also loads certain shaders for given entities:

  • Creeper → shaders/post/creeper.json
  • Spider (and cave spider) → shaders/post/spider.json
  • Enderman → shaders/post/invert.json
  • Anything else → the current shader is unloaded

Held Item Change (clientbound)

Sent to change the player's slot selection.

Packet ID State Bound To Field Name Field Type Notes
0x48 Play Client Slot Byte The slot which the player has selected (0–8).

Update View Position

Huh.png The following information needs to be added to this page:
Why is this even needed? Is there a better name for it? My guess is that it's something to do with logical behavior with latency, but it still seems weird.

Updates the client's location. This is used to determine what chunks should remain loaded and if a chunk load should be ignored; chunks outside of the view distance may be unloaded.

Sent whenever the player moves across a chunk border horizontally, and also (according to testing) for any integer change in the vertical axis, even if it doesn't go across a chunk section border.

Packet ID State Bound To Field Name Field Type Notes
0x49 Play Client Chunk X VarInt Chunk X coordinate of the player's position.
Chunk Z VarInt Chunk Z coordinate of the player's position.

Update View Distance

Sent by the integrated singleplayer server when changing render distance. This packet is sent by the server when the client reappears in the overworld after leaving the end.

Packet ID State Bound To Field Name Field Type Notes
0x4A Play Client View Distance VarInt Render distance (2-32).

Spawn Position

Sent by the server after login to specify the coordinates of the spawn point (the point at which players spawn at, and which the compass points to). It can be sent at any time to update the point compasses point at.

Packet ID State Bound To Field Name Field Type Notes
0x4B Play Client Location Position Spawn location.
Angle Float The angle at which to respawn at.

Display Scoreboard

This is sent to the client when it should display a scoreboard.

Packet ID State Bound To Field Name Field Type Notes
0x4C Play Client Position Byte The position of the scoreboard. 0: list, 1: sidebar, 2: below name, 3 - 18: team specific sidebar, indexed as 3 + team color.
Score Name String (16) The unique name for the scoreboard to be displayed.

Entity Metadata

Updates one or more metadata properties for an existing entity. Any properties not included in the Metadata field are left unchanged.

Packet ID State Bound To Field Name Field Type Notes
0x4D Play Client Entity ID VarInt
Metadata Entity Metadata

Attach Entity

This packet is sent when an entity has been leashed to another entity.

Packet ID State Bound To Field Name Field Type Notes
0x4E Play Client Attached Entity ID Int Attached entity's EID.
Holding Entity ID Int ID of the entity holding the lead. Set to -1 to detach.

Entity Velocity

Velocity is believed to be in units of 1/8000 of a block per server tick (50ms); for example, -1343 would move (-1343 / 8000) = −0.167875 blocks per tick (or −3,3575 blocks per second).

Packet ID State Bound To Field Name Field Type Notes
0x4F Play Client Entity ID VarInt
Velocity X Short Velocity on the X axis.
Velocity Y Short Velocity on the Y axis.
Velocity Z Short Velocity on the Z axis.

Entity Equipment

Packet ID State Bound To Field Name Field Type Notes
0x50 Play Client Entity ID VarInt Entity's EID.
Equipment Slot Array Byte Enum Equipment slot. 0: main hand, 1: off hand, 2–5: armor slot (2: boots, 3: leggings, 4: chestplate, 5: helmet). Also has the top bit set if another entry follows, and otherwise unset if this is the last item in the array.
Item Slot

Set Experience

Sent by the server when the client should change experience levels.

Packet ID State Bound To Field Name Field Type Notes
0x51 Play Client Experience bar Float Between 0 and 1.
Level VarInt
Total Experience VarInt See Experience#Leveling up on the Minecraft Wiki for Total Experience to Level conversion.

Update Health

Sent by the server to update/set the health of the player it is sent to.

Food saturation acts as a food “overcharge”. Food values will not decrease while the saturation is over zero. Players logging in automatically get a saturation of 5.0. Eating food increases the saturation as well as the food bar.

Packet ID State Bound To Field Name Field Type Notes
0x52 Play Client Health Float 0 or less = dead, 20 = full HP.
Food VarInt 0–20.
Food Saturation Float Seems to vary from 0.0 to 5.0 in integer increments.

Scoreboard Objective

This is sent to the client when it should create a new scoreboard objective or remove one.

Packet ID State Bound To Field Name Field Type Notes
0x53 Play Client Objective Name String (16) A unique name for the objective.
Mode Byte 0 to create the scoreboard. 1 to remove the scoreboard. 2 to update the display text.
Objective Value Optional Chat Only if mode is 0 or 2. The text to be displayed for the score.
Type Optional VarInt enum Only if mode is 0 or 2. 0 = "integer", 1 = "hearts".

Set Passengers

Packet ID State Bound To Field Name Field Type Notes
0x54 Play Client Entity ID VarInt Vehicle's EID.
Passenger Count VarInt Number of elements in the following array.
Passengers Array of VarInt EIDs of entity's passengers.

Teams

Creates and updates teams.

Packet ID State Bound To Field Name Field Type Notes
0x55 Play Client Team Name String (16) A unique name for the team. (Shared with scoreboard).
Mode Byte Determines the layout of the remaining packet.
0: create team Team Display Name Chat
Friendly Flags Byte Bit mask. 0x01: Allow friendly fire, 0x02: can see invisible players on same team.
Name Tag Visibility String Enum (32) always, hideForOtherTeams, hideForOwnTeam, never.
Collision Rule String Enum (32) always, pushOtherTeams, pushOwnTeam, never.
Team Color VarInt enum Used to color the name of players on the team; see below.
Team Prefix Chat Displayed before the names of players that are part of this team.
Team Suffix Chat Displayed after the names of players that are part of this team.
Entity Count VarInt Number of elements in the following array.
Entities Array of String (40) Identifiers for the entities in this team. For players, this is their username; for other entities, it is their UUID.
1: remove team no fields no fields
2: update team info Team Display Name Chat
Friendly Flags Byte Bit mask. 0x01: Allow friendly fire, 0x02: can see invisible entities on same team.
Name Tag Visibility String Enum (32) always, hideForOtherTeams, hideForOwnTeam, never
Collision Rule String Enum (32) always, pushOtherTeams, pushOwnTeam, never
Team Color VarInt enum Used to color the name of players on the team; see below.
Team Prefix Chat Displayed before the names of players that are part of this team.
Team Suffix Chat Displayed after the names of players that are part of this team.
3: add entities to team Entity Count VarInt Number of elements in the following array.
Entities Array of String (40) Identifiers for the added entities. For players, this is their username; for other entities, it is their UUID.
4: remove entities from team Entity Count VarInt Number of elements in the following array.
Entities Array of String (40) Identifiers for the removed entities. For players, this is their username; for other entities, it is their UUID.

Team Color: The color of a team defines how the names of the team members are visualized; any formatting code can be used. The following table lists all the possible values.

ID Formatting
0-15 Color formatting, same values as Chat colors.
16 Obfuscated
17 Bold
18 Strikethrough
19 Underlined
20 Italic
21 Reset

Update Score

This is sent to the client when it should update a scoreboard item.

Packet ID State Bound To Field Name Field Type Notes
0x56 Play Client Entity Name String (40) The entity whose score this is. For players, this is their username; for other entities, it is their UUID.
Action Byte 0 to create/update an item. 1 to remove an item.
Objective Name String (16) The name of the objective the score belongs to.
Value Optional VarInt The score to be displayed next to the entry. Only sent when Action does not equal 1.

Update Simulation Distance

Packet ID State Bound To Field Name Field Type Notes
0x57 Play Client Simulation Distance VarInt The distance that the client will process specific things, such as entities.

Set Title SubTitle

Packet ID State Bound To Field Name Field Type Notes
0x58 Play Client Subtitle Text Chat

Time Update

Time is based on ticks, where 20 ticks happen every second. There are 24000 ticks in a day, making Minecraft days exactly 20 minutes long.

The time of day is based on the timestamp modulo 24000. 0 is sunrise, 6000 is noon, 12000 is sunset, and 18000 is midnight.

The default SMP server increments the time by 20 every second.

Packet ID State Bound To Field Name Field Type Notes
0x59 Play Client World Age Long In ticks; not changed by server commands.
Time of day Long The world (or region) time, in ticks. If negative the sun will stop moving at the Math.abs of the time.

Set Title Text

Packet ID State Bound To Field Name Field Type Notes
0x5A Play Client Title Text Chat

Set Title Times

Packet ID State Bound To Field Name Field Type Notes
0x5B Play Client Fade In Int Ticks to spend fading in.
Stay Int Ticks to keep the title displayed.
Fade Out Int Ticks to spend out, not when to start fading out.

Entity Sound Effect

Plays a sound effect from an entity.

Warning.png The pitch and volume fields in this packet are ignored. See MC-138832 for more information.

Packet ID State Bound To Field Name Field Type Notes
0x5C Play Client Sound ID VarInt ID of hardcoded sound event (events as of 1.16.5).
Sound Category VarInt Enum The category that this sound will be played from (current categories).
Entity ID VarInt
Volume Float 1.0 is 100%, capped between 0.0 and 1.0 by Notchian clients.
Pitch Float Float between 0.5 and 2.0 by Notchian clients.

Sound Effect

This packet is used to play a number of hardcoded sound events. For custom sounds, use Named Sound Effect.

Warning.png Numeric sound effect IDs are liable to change between versions

Packet ID State Bound To Field Name Field Type Notes
0x5D Play Client Sound ID VarInt ID of hardcoded sound event (events as of 1.16.5).
Sound Category VarInt Enum The category that this sound will be played from (current categories).
Effect Position X Int Effect X multiplied by 8 (fixed-point number with only 3 bits dedicated to the fractional part).
Effect Position Y Int Effect Y multiplied by 8 (fixed-point number with only 3 bits dedicated to the fractional part).
Effect Position Z Int Effect Z multiplied by 8 (fixed-point number with only 3 bits dedicated to the fractional part).
Volume Float 1.0 is 100%, capped between 0.0 and 1.0 by Notchian clients.
Pitch Float Float between 0.5 and 2.0 by Notchian clients.

Stop Sound

Packet ID State Bound To Field Name Field Type Notes
0x5E Play Client Flags Byte Controls which fields are present.
Source Optional VarInt enum Only if flags is 3 or 1 (bit mask 0x1). See below. If not present, then sounds from all sources are cleared.
Sound Optional Identifier Only if flags is 2 or 3 (bit mask 0x2). A sound effect name, see Named Sound Effect. If not present, then all sounds are cleared.

Categories:

Name Value
master 0
music 1
record 2
weather 3
block 4
hostile 5
neutral 6
player 7
ambient 8
voice 9

Player List Header And Footer

This packet may be used by custom servers to display additional information above/below the player list. It is never sent by the Notchian server.

Packet ID State Bound To Field Name Field Type Notes
0x5F Play Client Header Chat To remove the header, send a empty text component: {"text":""}.
Footer Chat To remove the footer, send a empty text component: {"text":""}.

NBT Query Response

Sent in response to Query Block NBT or Query Entity NBT.

Packet ID State Bound To Field Name Field Type Notes
0x60 Play Client Transaction ID VarInt Can be compared to the one sent in the original query packet.
NBT NBT Tag The NBT of the block or entity. May be a TAG_END (0) in which case no NBT is present.

Collect Item

Sent by the server when someone picks up an item lying on the ground — its sole purpose appears to be the animation of the item flying towards you. It doesn't destroy the entity in the client memory, and it doesn't add it to your inventory. The server only checks for items to be picked up after each Player Position (and Player Position And Look) packet sent by the client. The collector entity can be any entity; it does not have to be a player. The collected entity also can be any entity, but the Notchian server only uses this for items, experience orbs, and the different varieties of arrows.

Packet ID State Bound To Field Name Field Type Notes
0x61 Play Client Collected Entity ID VarInt
Collector Entity ID VarInt
Pickup Item Count VarInt Seems to be 1 for XP orbs, otherwise the number of items in the stack.

Entity Teleport

This packet is sent by the server when an entity moves more than 8 blocks.

Packet ID State Bound To Field Name Field Type Notes
0x62 Play Client Entity ID VarInt
X Double
Y Double
Z Double
Yaw Angle (Y Rot)New angle, not a delta.
Pitch Angle (X Rot)New angle, not a delta.
On Ground Boolean

Advancements

Packet ID State Bound To Field Name Field Type Notes
0x63 Play Client Reset/Clear Boolean Whether to reset/clear the current advancements.
Mapping size VarInt Size of the following array.
Advancement mapping Key Array Identifier The identifier of the advancement.
Value Advancement See below
List size VarInt Size of the following array.
Identifiers Array of Identifier The identifiers of the advancements that should be removed.
Progress size VarInt Size of the following array.
Progress mapping Key Array Identifier The identifier of the advancement.
Value Advancement progress See below.

Advancement structure:

Field Name Field Type Notes
Has parent Boolean Indicates whether the next field exists.
Parent id Optional Identifier The identifier of the parent advancement.
Has display Boolean Indicates whether the next field exists.
Display data Optional advancement display See below.
Number of criteria VarInt Size of the following array.
Criteria Key Array Identifier The identifier of the criterion.
Value Void There is no content written here. Perhaps this will be expanded in the future?
Array length VarInt Number of arrays in the following array.
Requirements Array length 2 Array VarInt Number of elements in the following array.
Requirement Array of String Array of required criteria.

Advancement display:

Field Name Field Type Notes
Title Chat
Description Chat
Icon Slot
Frame type VarInt enum 0 = task, 1 = challenge, 2 = goal.
Flags Integer 0x01: has background texture; 0x02: show_toast; 0x04: hidden.
Background texture Optional Identifier Background texture location. Only if flags indicates it.
X coord Float
Y coord Float

Advancement progress:

Field Name Field Type Notes
Size VarInt Size of the following array.
Criteria Criterion identifier Array Identifier The identifier of the criterion.
Criterion progress Criterion progress

Criterion progress:

Field Name Field Type Notes
Achieved Boolean If true, next field is present.
Date of achieving Optional Long As returned by Date.getTime.

Entity Properties

Sets attributes on the given entity.

Packet ID State Bound To Field Name Field Type Notes
0x64 Play Client Entity ID VarInt
Number Of Properties VarInt Number of elements in the following array.
Property Key Array Identifier 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.max_health 20.0 0.0 1024.0 Max Health.
generic.follow_range 32.0 0.0 2048.0 Follow Range.
generic.knockback_resistance 0.0 0.0 1.0 Knockback Resistance.
generic.movement_speed 0.7 0.0 1024.0 Movement Speed.
generic.attack_damage 2.0 0.0 2048.0 Attack Damage.
generic.attack_speed 4.0 0.0 1024.0 Attack Speed.
generic.flying_speed 0.4 0.0 1024.0 Flying Speed.
generic.armor 0.0 0.0 30.0 Armor.
generic.armor_toughness 0.0 0.0 20.0 Armor Toughness.
generic.attack_knockback 0.0 0.0 5.0 —
generic.luck 0.0 -1024.0 1024.0 Luck.
horse.jump_strength 0.7 0.0 2.0 Jump Strength.
zombie.spawn_reinforcements 0.0 0.0 1.0 Spawn Reinforcements Chance.
generic.reachDistance 5.0 0.0 1024.0 Player Reach Distance (Forge only).
forge.swimSpeed 1.0 0.0 1024.0 Swimming Speed (Forge only).

Unknown attributes will cause a game crash (MC-150405) due to the default minimum being larger than the default value.

Modifier Data structure:

Field Name Field Type Notes
UUID UUID
Amount Double May be positive or negative.
Operation Byte See below.

The operation controls how the base value of the modifier is changed.

  • 0: Add/subtract amount
  • 1: Add/subtract amount percent of the current value
  • 2: Multiply by amount percent

All of the 0's are applied first, and then the 1's, and then the 2's.

Entity Effect

Packet ID State Bound To Field Name Field Type Notes
0x65 Play Client Entity ID VarInt
Effect ID Byte See this table.
Amplifier Byte Notchian client displays effect level as Amplifier + 1.
Duration VarInt Duration in ticks.
Flags Byte Bit field, see below.

Within flags:

  • 0x01: Is ambient - was the effect spawned from a beacon? All beacon-generated effects are ambient. Ambient effects use a different icon in the HUD (blue border rather than gray). If all effects on an entity are ambient, the "Is potion effect ambient" living metadata field should be set to true. Usually should not be enabled.
  • 0x02: Show particles - should all particles from this effect be hidden? Effects with particles hidden are not included in the calculation of the effect color, and are not rendered on the HUD (but are still rendered within the inventory). Usually should be enabled.
  • 0x04: Show icon - should the icon be displayed on the client? Usually should be enabled.

Declare Recipes

Packet ID State Bound To Field Name Field Type Notes
0x66 Play Client Num Recipes VarInt Number of elements in the following array.
Recipe Type Array Identifier The recipe type, see below.
Recipe ID Identifier
Data Optional, varies Additional data for the recipe. For some types, there will be no data.

Recipe types:

Type Description Data
crafting_shapeless Shapeless crafting recipe. All items in the ingredient list must be present, but in any order/slot. As follows:
Name Type Description
Group String Used to group similar recipes together in the recipe book. Tag is present in recipe JSON.
Ingredient count VarInt Number of elements in the following array.
Ingredients Array of Ingredient.
Result Slot
crafting_shaped Shaped crafting recipe. All items must be present in the same pattern (which may be flipped horizontally or translated). As follows:
Name Type Description
Width VarInt
Height VarInt
Group String Used to group similar recipes together in the recipe book. Tag is present in recipe JSON.
Ingredients Array of Ingredient Length is width * height. Indexed by x + (y * width).
Result Slot
crafting_special_armordye Recipe for dying leather armor None
crafting_special_bookcloning Recipe for copying contents of written books
crafting_special_mapcloning Recipe for copying maps
crafting_special_mapextending Recipe for adding paper to maps
crafting_special_firework_rocket Recipe for making firework rockets
crafting_special_firework_star Recipe for making firework stars
crafting_special_firework_star_fade Recipe for making firework stars fade between multiple colors
crafting_special_repairitem Recipe for repairing items via crafting
crafting_special_tippedarrow Recipe for crafting tipped arrows
crafting_special_bannerduplicate Recipe for copying banner patterns
crafting_special_banneraddpattern Recipe for adding patterns to banners
crafting_special_shielddecoration Recipe for applying a banner's pattern to a shield
crafting_special_shulkerboxcoloring Recipe for recoloring a shulker box
crafting_special_suspiciousstew
smelting Smelting recipe As follows:
Name Type Description
Group String Used to group similar recipes together in the recipe book.
Ingredient Ingredient
Result Slot
Experience Float
Cooking time VarInt
blasting Blast furnace recipe
smoking Smoker recipe
campfire_cooking Campfire recipe
stonecutting Stonecutter recipe As follows:
Name Type Description
Group String Used to group similar recipes together in the recipe book. Tag is present in recipe JSON.
Ingredient Ingredient
Result Slot
smithing Smithing table recipe As follows:
Name Type Description
Base Ingredient First item.
Addition Ingredient Second item.
Result Slot

Ingredient is defined as:

Name Type Description
Count VarInt Number of elements in the following array.
Items Array of Slot Any item in this array may be used for the recipe. The count of each item should be 1.

Tags

Packet ID State Bound To Field Name Field Type Notes
0x67 Play Client Length of the array VarInt
Array of tags Tag type Array Identifier Tag identifier (Vanilla required tags are minecraft:block, minecraft:item, minecraft:fluid, minecraft:entity_type, and minecraft:game_event)
Array of Tag (See below)

Tags look like:

Field Name Field Type Notes
Length VarInt Number of elements in the following array
Tags Tag name Array Identifier
Count VarInt Number of elements in the following array
Entries Array of VarInt Numeric ID of the given type (block, item, etc.).

More information on tags is available at: https://minecraft.gamepedia.com/Tag

And a list of all tags is here: https://minecraft.gamepedia.com/Tag#List_of_tags

Serverbound

Teleport Confirm

Sent by client as confirmation of Player Position And Look.

Packet ID State Bound To Field Name Field Type Notes
0x00 Play Server Teleport ID VarInt The ID given by the Player Position And Look packet.

Query Block NBT

Used when Shift+F3+I is pressed while looking at a block.

Packet ID State Bound To Field Name Field Type Notes
0x01 Play Server Transaction ID VarInt An incremental ID so that the client can verify that the response matches.
Location Position The location of the block to check.

Set Difficulty

Must have at least op level 2 to use. Appears to only be used on singleplayer; the difficulty buttons are still disabled in multiplayer.

Packet ID State Bound To Field Name Field Type Notes
0x02 Play Server New difficulty Byte 0: peaceful, 1: easy, 2: normal, 3: hard .

Chat Message (serverbound)

Used to send a chat message to the server. The message may not be longer than 256 characters or else the server will kick the client.

If the message starts with a /, the server will attempt to interpret it as a command. Otherwise, the server will broadcast the same chat message to all players on the server (including the player that sent the message), prepended with player's name. Specifically, it will respond with a translate chat component, "chat.type.text" with the first parameter set to the display name of the player (including some chat component logic to support clicking the name to send a PM) and the second parameter set to the message. See processing chat for more information.

Packet ID State Bound To Field Name Field Type Notes
0x03 Play Server Message String (256) The client sends the raw input, not a Chat component.

Client Status

Packet ID State Bound To Field Name Field Type Notes
0x04 Play Server Action ID VarInt Enum See below

Action ID values:

Action ID Action Notes
0 Perform respawn Sent when the client is ready to complete login and when the client is ready to respawn after death.
1 Request stats Sent when the client opens the Statistics menu.

Client Settings

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

Packet ID State Bound To Field Name Field Type Notes
0x05 Play Server Locale String (16) e.g. en_GB.
View Distance Byte Client-side render distance, in chunks.
Chat Mode VarInt Enum 0: enabled, 1: commands only, 2: hidden. See processing chat for more information.
Chat Colors Boolean “Colors” multiplayer setting. Can the chat be colored?
Displayed Skin Parts Unsigned Byte Bit mask, see below.
Main Hand VarInt Enum 0: Left, 1: Right.
Enable text filtering Boolean Enables filtering of text on signs and written book titles. Currently always false (i.e. the filtering is disabled)
Allow server listings Boolean Servers usually list online players, this option should let you not show up in that list.

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.

Tab-Complete (serverbound)

Sent when the client needs to tab-complete a minecraft:ask_server suggestion type.

Packet ID State Bound To Field Name Field Type Notes
0x06 Play Server Transaction Id VarInt The id of the transaction that the server will send back to the client in the response of this packet. Client generates this and increments it each time it sends another tab completion that doesn't get a response.
Text String (32500) All text behind the cursor without the / (e.g. to the left of the cursor in left-to-right languages like English).

Click Window Button

Used when clicking on window buttons. Until 1.14, this was only used by enchantment tables.

Packet ID State Bound To Field Name Field Type Notes
0x07 Play Server Window ID Byte The ID of the window sent by Open Window.
Button ID Byte Meaning depends on window type; see below.
Window type ID Meaning
Enchantment Table 0 Topmost enchantment.
1 Middle enchantment.
2 Bottom enchantment.
Lectern 1 Previous page (which does give a redstone output).
2 Next page.
3 Take Book.
100+page Opened page number - 100 + number.
Stonecutter Recipe button number - 4*row + col. Depends on the item.
Loom Recipe button number - 4*row + col. Depends on the item.

Click Window

This packet is sent by the client when the player clicks on a slot in a window.

Packet ID State Bound To Field Name Field Type Notes
0x08 Play Server Window ID Unsigned Byte The ID of the window which was clicked. 0 for player inventory.
State ID VarInt The last recieved State ID from either a Set Slot or a Window Items packet
Slot Short The clicked slot number, see below.
Button Byte The button used in the click, see below.
Mode VarInt Enum Inventory operation mode, see below.
Length of the array VarInt
Array of slots Slot number Array Short
Slot data Slot New data for this slot
Clicked item Slot The clicked slot. Has to be empty (item ID = -1) for drop mode. Is always empty for mode 2 and mode 5 packets.

See Inventory for further information about how slots are indexed.

When right-clicking on a stack of items, half the stack will be picked up and half left in the slot. If the stack is an odd number, the half left in the slot will be smaller of the amounts.

The distinct type of click performed by the client is determined by the combination of the Mode and Button fields.

Mode Button Slot Trigger
0 0 Normal Left mouse click
1 Normal Right mouse click
0 -999 Left click outside inventory (drop cursor stack)
1 -999 Right click outside inventory (drop cursor single item)
1 0 Normal Shift + left mouse click
1 Normal Shift + right mouse click (identical behavior)
2 0 Normal Number key 1
1 Normal Number key 2
2 Normal Number key 3
⋮ ⋮ ⋮
8 Normal Number key 9
40 Normal Offhand swap key F
3 2 Normal Middle click, only defined for creative players in non-player inventories.
4 0 Normal* Drop key (Q) (* Clicked item is always empty)
1 Normal* Control + Drop key (Q) (* Clicked item is always empty)
5 0 -999 Starting left mouse drag
4 -999 Starting right mouse drag
8 -999 Starting middle mouse drag, only defined for creative players in non-player inventories. (Note: the vanilla client will still incorrectly send this for non-creative players - see MC-46584)
1 Normal Add slot for left-mouse drag
5 Normal Add slot for right-mouse drag
9 Normal Add slot for middle-mouse drag, only defined for creative players in non-player inventories. (Note: the vanilla client will still incorrectly send this for non-creative players - see MC-46584)
2 -999 Ending left mouse drag
6 -999 Ending right mouse drag
10 -999 Ending middle mouse drag, only defined for creative players in non-player inventories. (Note: the vanilla client will still incorrectly send this for non-creative players - see MC-46584)
6 0 Normal Double click

Starting from version 1.5, “painting mode” is available for use in inventory windows. It is done by picking up stack of something (more than 1 item), then holding mouse button (left, right or middle) and dragging held stack over empty (or same type in case of right button) slots. In that case client sends the following to server after mouse button release (omitting first pickup packet which is sent as usual):

  1. packet with mode 5, slot -999, button (0 for left | 4 for right);
  2. packet for every slot painted on, mode is still 5, button (1 | 5);
  3. packet with mode 5, slot -999, button (2 | 6);

If any of the painting packets other than the “progress” ones are sent out of order (for example, a start, some slots, then another start; or a left-click in the middle) the painting status will be reset.

Close Window (serverbound)

This packet is sent by the client when closing a window.

Notchian clients send a Close Window packet with Window ID 0 to close their inventory even though there is never an Open Window packet for the inventory.

Packet ID State Bound To Field Name Field Type Notes
0x09 Play Server Window ID Unsigned Byte This is the ID of the window that was closed. 0 for player inventory.

Plugin Message (serverbound)

Main article: Plugin channels

Mods and plugins can use this to send their data. Minecraft itself uses some plugin channels. These internal channels are in the minecraft namespace.

More documentation on this: https://dinnerbone.com/blog/2012/01/13/minecraft-plugin-channels-messaging/

Note that the length of Data is known only from the packet length, since the packet has no length field of any kind.

Packet ID State Bound To Field Name Field Type Notes
0x0A Play Server Channel Identifier Name of the plugin channel used to send the data.
Data Byte Array Any data, depending on the channel. minecraft: channels are documented here. The length of this array must be inferred from the packet length.

Edit Book

Packet ID State Bound To Field Name Field Type Notes
0x0B Play Server Hand VarInt enum 0: Main hand, 1: Off hand.
Count VarInt Number of elements in the following array
Entries Array of Strings Text from each page.
Has title Boolean If true, the next field is present.
Title String Title of book.

When editing a draft, the NBT section of the Slot contains this: 

TAG_Compound(''): 1 entry
{
  TAG_List('pages'): 2 entries
  {
    TAG_String(0): 'Something on Page 1'
    TAG_String(1): 'Something on Page 2'
  }
}

When signing the book, it instead looks like this: 

TAG_Compound(''): 3 entires
{
  TAG_String('author'): 'Steve'
  TAG_String('title'): 'A Wonderful Book'
  TAG_List('pages'): 2 entries
  {
    TAG_String(0): 'Something on Page 1'
    TAG_String(1): 'Something on Page 2'
  }
}

Query Entity NBT

Used when Shift+F3+I is pressed while looking at an entity.

Packet ID State Bound To Field Name Field Type Notes
0x0C Play Server Transaction ID VarInt An incremental ID so that the client can verify that the response matches.
Entity ID VarInt The ID of the entity to query.

Interact 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.

The target X, Y, and Z fields represent the difference between the vector location of the cursor at the time of the packet and the entity'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
0x0D Play Server Entity ID VarInt The ID of the entity to interact.
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.
Sneaking Boolean If the client is sneaking.

Generate Structure

Sent when Generate is pressed on the Jigsaw Block interface.

Packet ID State Bound To Field Name Field Type Notes
0x0E Play Server Location Position Block entity location.
Levels VarInt Value of the levels slider/max depth to generate.
Keep Jigsaws Boolean

Keep Alive (serverbound)

The server will frequently send out a keep-alive, each containing a random ID. The client must respond with the same packet.

Packet ID State Bound To Field Name Field Type Notes
0x0F Play Server Keep Alive ID Long

Lock Difficulty

Must have at least op level 2 to use. Appears to only be used on singleplayer; the difficulty buttons are still disabled in multiplayer.

Packet ID State Bound To Field Name Field Type Notes
0x10 Play Server Locked Boolean

Player Position

Updates the player's XYZ position on the server.

Checking for moving too fast is achieved like this:

  • Each server tick, the player's current position is stored
  • When a player moves, the changes in x, y, and z coordinates are compared with the positions from the previous tick (Δx, Δy, Δz)
  • Total movement distance squared is computed as Δx² + Δy² + Δz²
  • The expected movement distance squared is computed as velocityX² + velocityY² + velocityZ²
  • If the total movement distance squared value minus the expected movement distance squared value is more than 100 (300 if the player is using an elytra), they are moving too fast.

If the player is moving too fast, it will be logged that "<player> moved too quickly! " followed by the change in x, y, and z, and the player will be teleported back to their current (before this packet) serverside position.

Also, if the absolute value of X or the absolute value of Z is a value greater than 3.2×107, or X, Y, or Z are not finite (either positive infinity, negative infinity, or NaN), the client will be kicked for “Invalid move player packet received”.

Packet ID State Bound To Field Name Field Type Notes
0x11 Play Server X Double Absolute position.
Feet Y Double Absolute feet position, normally Head Y - 1.62.
Z Double Absolute position.
On Ground Boolean True if the client is on the ground, false otherwise.

Player Position And Rotation (serverbound)

A combination of Player Rotation and Player Position.

Packet ID State Bound To Field Name Field Type Notes
0x12 Play Server X Double Absolute position.
Feet Y Double Absolute feet position, normally Head Y - 1.62.
Z Double Absolute position.
Yaw Float Absolute rotation on the X Axis, in degrees.
Pitch Float Absolute rotation on the Y Axis, in degrees.
On Ground Boolean True if the client is on the ground, false otherwise.

Player Rotation

The unit circle for yaw
The unit circle of yaw, redrawn

Updates the direction the player is looking in.

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 and pitch of player (in degrees), standing at point (x0, y0, z0) and looking towards point (x, y, z) can be calculated with: 

dx = x-x0
dy = y-y0
dz = z-z0
r = sqrt( dx*dx + dy*dy + dz*dz )
yaw = -atan2(dx,dz)/PI*180
if yaw < 0 then
    yaw = 360 + yaw
pitch = -arcsin(dy/r)/PI*180

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
0x13 Play Server Yaw Float Absolute rotation on the X Axis, in degrees.
Pitch Float Absolute rotation on the Y Axis, in degrees.
On Ground Boolean True if the client is on the ground, false otherwise.

Player Movement

This packet as well as Player Position, Player Look, and Player Position And Look are called the “serverbound movement packets”. Vanilla clients will send Player Position once every 20 ticks even for a stationary player.

This packet is used to indicate whether the player is on ground (walking/swimming), or airborne (jumping/falling).

When dropping from sufficient height, fall damage is applied when this state goes from false to true. The amount of damage applied is based on the point where it last changed from true to false. Note that there are several movement related packets containing this state.

Packet ID State Bound To Field Name Field Type Notes
0x14 Play Server On Ground Boolean True if the client is on the ground, false otherwise.

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
0x15 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

Used to visually update whether boat paddles are turning. The server will update the Boat entity metadata to match the values here.

Packet ID State Bound To Field Name Field Type Notes
0x16 Play Server Left paddle turning Boolean
Right paddle turning Boolean

Right paddle turning is set to true when the left button or forward button is held, left paddle turning is set to true when the right button or forward button is held.

Pick Item

Used to swap out an empty space on the hotbar with the item in the given inventory slot. The Notchain client uses this for pick block functionality (middle click) to retrieve items from the inventory.

Packet ID State Bound To Field Name Field Type Notes
0x17 Play Server Slot to use VarInt See Inventory.

The server will first search the player's hotbar for an empty slot, starting from the current slot and looping around to the slot before it. If there are no empty slots, it will start a second search from the current slot and find the first slot that does not contain an enchanted item. If there still are no slots that meet that criteria, then the server will use the currently selected slot.

After finding the appropriate slot, the server swaps the items and then send 3 packets:

  • Set Slot, with window ID set to -2 and slot set to the newly chosen slot and the item set to the item that is now in that slot (which was previously at the slot the client requested)
  • Set Slot, with window ID set to -2 and slot set to the slot the player requested, with the item that is now in that slot and was previously on the hotbar slot
  • Held Item Change, with the slot set to the newly chosen slot.

Craft Recipe Request

This packet is sent when a player clicks a recipe in the crafting book that is craftable (white border).

Packet ID State Bound To Field Name Field Type Notes
0x18 Play Server Window ID Byte
Recipe Identifier A recipe ID.
Make all Boolean Affects the amount of items processed; true if shift is down when clicked.

Player Abilities (serverbound)

The vanilla client sends this packet when the player starts/stops flying with the Flags parameter changed accordingly.

Packet ID State Bound To Field Name Field Type Notes
0x19 Play Server Flags Byte Bit mask. 0x02: is flying.

Player Digging

Sent when the player mines a block. A Notchian server only accepts digging packets with coordinates within a 6-unit radius between the center of the block and 1.5 units from the player's feet (not their eyes).

Packet ID State Bound To Field Name Field Type Notes
0x1A Play Server Status VarInt 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 Indicates that the currently held item should have its state updated such as eating food, pulling back bows, using buckets, etc. Location is always set to 0/0/0, Face is always set to -Y.
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:

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

Entity Action

Sent by the client to indicate that it has performed certain actions: sneaking (crouching), sprinting, exiting a bed, jumping with a horse, and opening a horse's inventory while riding it.

Packet ID State Bound To Field Name Field Type Notes
0x1B Play Server Entity ID VarInt Player ID
Action ID VarInt Enum The ID of the action, see below.
Jump Boost VarInt Only used by the “start jump with horse” action, in which case it ranges from 0 to 100. In all other cases it is 0.

Action ID can be one of the following values:

ID Action
0 Start sneaking
1 Stop sneaking
2 Leave bed
3 Start sprinting
4 Stop sprinting
5 Start jump with horse
6 Stop jump with horse
7 Open horse inventory
8 Start flying with elytra

Leave bed is only sent when the “Leave Bed” button is clicked on the sleep GUI, not when waking up due today time.

Open horse inventory is only sent when pressing the inventory key (default: E) while on a horse — all other methods of opening a horse's inventory (involving right-clicking or shift-right-clicking it) do not use this packet.

Steer Vehicle

Packet ID State Bound To Field Name Field Type Notes
0x1C Play Server Sideways Float Positive to the left of the player.
Forward Float Positive forward.
Flags Unsigned Byte Bit mask. 0x1: jump, 0x2: unmount.

Also known as 'Input' packet.

Pong

Response to the clientbound packet (Ping) with the same id.

Packet ID State Bound To Field Name Field Type Notes
0x1D Play Server ID Int id is the same as the ping packet

Set Recipe Book State

Replaces Recipe Book Data, type 1.

Packet ID State Bound To Field Name Field Type Notes
0x1E Play Server Book ID VarInt enum 0: crafting, 1: furnace, 2: blast furnace, 3: smoker.
Book Open Boolean
Filter Active Boolean

Set Displayed Recipe

Replaces Recipe Book Data, type 0.

Packet ID State Bound To Field Name Field Type Notes
0x1F Play Server Recipe ID Identifier

Name Item

Sent as a player is renaming an item in an anvil (each keypress in the anvil UI sends a new Name Item packet). If the new name is empty, then the item loses its custom name (this is different from setting the custom name to the normal name of the item). The item name may be no longer than 35 characters long, and if it is longer than that, then the rename is silently ignored.

Packet ID State Bound To Field Name Field Type Notes
0x20 Play Server Item name String (32767) The new name of the item.

Resource Pack Status

Packet ID State Bound To Field Name Field Type Notes
0x21 Play Server Result VarInt Enum 0: successfully loaded, 1: declined, 2: failed download, 3: accepted.

Advancement Tab

Packet ID State Bound To Field Name Field Type Notes
0x22 Play Server Action VarInt enum 0: Opened tab, 1: Closed screen.
Tab ID Optional identifier Only present if action is Opened tab.

Select Trade

When a player selects a specific trade offered by a villager NPC.

Packet ID State Bound To Field Name Field Type Notes
0x23 Play Server Selected slot VarInt The selected slot in the players current (trading) inventory. (Was a full Integer for the plugin message).

Set Beacon Effect

Changes the effect of the current beacon.

Packet ID State Bound To Field Name Field Type Notes
0x24 Play Server Primary Effect VarInt A Potion ID. (Was a full Integer for the plugin message).
Secondary Effect VarInt A Potion ID. (Was a full Integer for the plugin message).

Held Item Change (serverbound)

Sent when the player changes the slot selection

Packet ID State Bound To Field Name Field Type Notes
0x25 Play Server Slot Short The slot which the player has selected (0–8).

Update Command Block

Packet ID State Bound To Field Name Field Type Notes
0x26 Play Server
Location Position
Command String (32767)
Mode VarInt enum One of SEQUENCE (0), AUTO (1), or REDSTONE (2).
Flags Byte 0x01: Track Output (if false, the output of the previous command will not be stored within the command block); 0x02: Is conditional; 0x04: Automatic.

Update Command Block Minecart

Packet ID State Bound To Field Name Field Type Notes
0x27 Play Server Entity ID VarInt
Command String
Track Output Boolean If false, the output of the previous command will not be stored within the command block.

Creative Inventory Action

While the user is in the standard inventory (i.e., not a crafting bench) in Creative mode, the player will send this packet.

Clicking in the creative inventory menu is quite different from non-creative inventory management. Picking up an item with the mouse actually deletes the item from the server, and placing an item into a slot or dropping it out of the inventory actually tells the server to create the item from scratch. (This can be verified by clicking an item that you don't mind deleting, then severing the connection to the server; the item will be nowhere to be found when you log back in.) As a result of this implementation strategy, the "Destroy Item" slot is just a client-side implementation detail that means "I don't intend to recreate this item.". Additionally, the long listings of items (by category, etc.) are a client-side interface for choosing which item to create. Picking up an item from such listings sends no packets to the server; only when you put it somewhere does it tell the server to create the item in that location.

This action can be described as "set inventory slot". Picking up an item sets the slot to item ID -1. Placing an item into an inventory slot sets the slot to the specified item. Dropping an item (by clicking outside the window) effectively sets slot -1 to the specified item, which causes the server to spawn the item entity, etc.. All other inventory slots are numbered the same as the non-creative inventory (including slots for the 2x2 crafting menu, even though they aren't visible in the vanilla client).

Packet ID State Bound To Field Name Field Type Notes
0x28 Play Server Slot Short Inventory slot.
Clicked Item Slot

Update Jigsaw Block

Sent when Done is pressed on the Jigsaw Block interface.

Packet ID State Bound To Field Name Field Type Notes
0x29 Play Server Location Position Block entity location
Name Identifier
Target Identifier
Pool Identifier
Final state String "Turns into" on the GUI, final_state in NBT.
Joint type String rollable if the attached piece can be rotated, else aligned.

Update Structure Block

Packet ID State Bound To Field Name Field Type Notes
0x2A Play Server
Location Position Block entity location.
Action VarInt enum An additional action to perform beyond simply saving the given data; see below.
Mode VarInt enum One of SAVE (0), LOAD (1), CORNER (2), DATA (3).
Name String
Offset X Byte Between -32 and 32.
Offset Y Byte Between -32 and 32.
Offset Z Byte Between -32 and 32.
Size X Byte Between 0 and 32.
Size Y Byte Between 0 and 32.
Size Z Byte Between 0 and 32.
Mirror VarInt enum One of NONE (0), LEFT_RIGHT (1), FRONT_BACK (2).
Rotation VarInt enum One of NONE (0), CLOCKWISE_90 (1), CLOCKWISE_180 (2), COUNTERCLOCKWISE_90 (3).
Metadata String
Integrity Float Between 0 and 1.
Seed VarLong
Flags Byte 0x01: Ignore entities; 0x02: Show air; 0x04: Show bounding box.

Possible actions:

  • 0 - Update data
  • 1 - Save the structure
  • 2 - Load the structure
  • 3 - Detect size

The Notchian client uses update data to indicate no special action should be taken (i.e. the done button).

Update Sign

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

The server only accepts this packet after Open Sign Editor, otherwise this packet is silently ignored.

Packet ID State Bound To Field Name Field Type Notes
0x2B Play Server Location Position Block Coordinates.
Line 1 String (384) First line of text in the sign.
Line 2 String (384) Second line of text in the sign.
Line 3 String (384) Third line of text in the sign.
Line 4 String (384) Fourth line of text in the sign.

Animation (serverbound)

Sent when the player's arm swings.

Packet ID State Bound To Field Name Field Type Notes
0x2C Play Server Hand VarInt Enum Hand used for the animation. 0: main hand, 1: off hand.

Spectate

Teleports the player to the given entity. The player must be in spectator mode.

The Notchian client only uses this to teleport to players, but it appears to accept any type of entity. The entity does not need to be in the same dimension as the player; if necessary, the player will be respawned in the right world. If the given entity cannot be found (or isn't loaded), this packet will be ignored. It will also be ignored if the player attempts to teleport to themselves.

Packet ID State Bound To Field Name Field Type Notes
0x2D Play Server Target Player UUID UUID of the player to teleport to (can also be an entity UUID).

Player Block Placement

Packet ID State Bound To Field Name Field Type Notes
0x2E Play Server Hand VarInt Enum The hand from which the block is placed; 0: main hand, 1: off hand.
Location Position Block position.
Face VarInt Enum The face on which the block is placed (as documented at Player Digging).
Cursor Position X Float The position of the crosshair on the block, from 0 to 1 increasing from west to east.
Cursor Position Y Float The position of the crosshair on the block, from 0 to 1 increasing from bottom to top.
Cursor Position Z Float The position of the crosshair on the block, from 0 to 1 increasing from north to south.
Inside block Boolean True when the player's head is inside of a block.

Upon placing a block, this packet is sent once.

The Cursor Position X/Y/Z fields (also known as in-block coordinates) are calculated using raytracing. The unit corresponds to sixteen pixels 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 0.0–0.5) or as a top slab (values 0.5-1.0). The Cursor Position Z should be 1.0 since the player was looking at the southernmost part of the block.

Inside block is true when a player's head (specifically eyes) are inside of a block's collision. In 1.13 and later versions, collision is rather complicated and individual blocks can have multiple collision boxes. For instance, a ring of vines has a non-colliding hole in the middle. This value is only true when the player is directly in the box. In practice, though, this value is only used by scaffolding to place in front of the player when sneaking inside of it (other blocks will place behind when you intersect with them -- try with glass for instance).

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
0x2F Play Server Hand VarInt Enum Hand used for the animation. 0: main hand, 1: off hand.
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