Difference between revisions of "Pre-release protocol"

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m (Fixed broken table)
(Updated entity properties array length to VarInt)
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{{PacketList|{{change|0x56|0x60}}|Entity Teleport|pre=unchanged}}
 
{{PacketList|{{change|0x56|0x60}}|Entity Teleport|pre=unchanged}}
 
{{PacketList|{{change|0x57|0x61}}|Advancements|pre=unchanged}}
 
{{PacketList|{{change|0x57|0x61}}|Advancements|pre=unchanged}}
{{PacketList|{{change|0x58|0x62}}|Entity Properties|pre=unchanged}}
+
{{PacketList|{{change|0x58|0x62}}|Entity Properties}}
 
{{PacketList|{{change|0x59|0x63}}|Entity Effect|pre=unchanged}}
 
{{PacketList|{{change|0x59|0x63}}|Entity Effect|pre=unchanged}}
 
{{PacketList|{{change|0x5A|0x64}}|Declare Recipes|pre=unchanged}}
 
{{PacketList|{{change|0x5A|0x64}}|Declare Recipes|pre=unchanged}}
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  |}
 
  |}
  
 +
 +
==== Entity Properties ====
 +
 +
Sets {{Minecraft Wiki|Attribute|attributes}} on the given entity.
 +
 +
{| class="wikitable"
 +
! Packet ID
 +
! State
 +
! Bound To
 +
!colspan="2"| Field Name
 +
!colspan="2"| Field Type
 +
! Notes
 +
|-
 +
|rowspan="6"| {{change|0x58|0x63}}
 +
|rowspan="6"| Play
 +
|rowspan="6"| Client
 +
|colspan="2"| Entity ID
 +
|colspan="2"| VarInt
 +
|
 +
|-
 +
|colspan="2"| Number Of Properties
 +
|colspan="2"| {{change|Int|VarInt}}
 +
| Number of elements in the following array.
 +
|-
 +
|rowspan="4"| Property
 +
| Key
 +
|rowspan="4"| 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 {{Minecraft Wiki|Attribute#Modifiers}}. Modifier Data defined below.
 +
|}
 +
 +
Known Key values (see also {{Minecraft Wiki|Attribute#Modifiers}}):
 +
 +
{| class="wikitable"
 +
|-
 +
! 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 ([https://bugs.mojang.com/browse/MC-150405 MC-150405]) due to the default minimum being larger than the default value.
 +
 +
''Modifier Data'' structure:
 +
 +
{| class="wikitable"
 +
|-
 +
! 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.
  
 
==== Tags ====
 
==== Tags ====

Revision as of 08:57, 10 June 2021

This page documents the changes from the last stable Minecraft release (currently 1.16.5, protocol 754) to the current pre-release (currently 21w07a, protocol Snapshot 15). Note that this page contains bleeding-edge information that may not be completely or correctly documented.

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

Contents

Data types

No changes so far.

Packets

ID Packet name Documentation
Play clientbound
0x05 Sculk Vibration Signal Pre
0x05 0x06 Entity Animation (clientbound) Current (unchanged)
0x06 0x07 Statistics Current (unchanged)
0x07 0x08 Acknowledge Player Digging Current (unchanged)
0x08 0x09 Block Break Animation Current (unchanged)
0x09 0x0A Block Entity Data Current (unchanged)
0x0A 0x0B Block Action Current (unchanged)
0x0B 0x0C Block Change Current (unchanged)
0x0C 0x0D Boss Bar Current (unchanged)
0x0D 0x0E Server Difficulty Current (unchanged)
0x0E 0x0F Chat Message (clientbound) Current (unchanged)
0x10 Clear Titles Pre
0x0F 0x11 Tab-Complete (clientbound) Current (unchanged)
0x10 0x12 Declare Commands Current (unchanged)
0x11 Window Confirmation (clientbound) Current
0x12 0x13 Close Window (clientbound) Current (unchanged)
0x13 0x14 Window Items Current (unchanged)
0x14 0x15 Window Property Current (unchanged)
0x15 0x16 Set Slot Current (unchanged)
0x16 0x17 Set Cooldown Current (unchanged)
0x17 0x18 Plugin Message (clientbound) Current (unchanged)
0x18 0x19 Named Sound Effect Current (unchanged)
0x19 0x1A Disconnect (play) Current (unchanged)
0x1A 0x1B Entity Status Current (unchanged)
0x1B 0x1C Explosion Current (unchanged)
0x1C 0x1D Unload Chunk Current (unchanged)
0x1D 0x1E Change Game State Current (unchanged)
0x1E 0x1F Open Horse Window Current (unchanged)
0x20 Initialize World Border Pre
0x1F 0x21 Keep Alive (clientbound) Current (unchanged)
0x20 0x22 Chunk Data Current Pre
0x21 0x23 Effect Current (unchanged)
0x22 0x24 Particle Current (unchanged)
0x23 0x25 Update Light Current Pre
0x24 0x26 Join Game Current (unchanged)
0x25 0x27 Map Data Current Pre
0x26 0x28 Trade List Current (unchanged)
0x27 0x29 Entity Position Current (unchanged)
0x28 0x2A Entity Position and Rotation Current (unchanged)
0x29 0x2B Entity Rotation Current (unchanged)
0x2A Entity Movement Current
0x2B 0x2C Vehicle Move (clientbound) Current (unchanged)
0x2C 0x2D Open Book Current (unchanged)
0x2D 0x2E Open Window Current (unchanged)
0x2E 0x2F Open Sign Editor Current (unchanged)
0x2F 0x30 Craft Recipe Response Current (unchanged)
0x30 0x31 Player Abilities (clientbound) Current (unchanged)
0x31 Combat Event Current
0x32 End Combat Event Pre
0x33 Enter Combat Event Pre
0x34 Death Combat Event Pre
0x32 0x35 Player Info Current (unchanged)
0x33 0x36 Face Player Current (unchanged)
0x36 Destroy Entities Current
0x34 0x37 Player Position And Look (clientbound) Current Pre
0x35 0x38 Unlock Recipes Current (unchanged)
0x39 Destroy Entity Pre
0x37 0x3A Remove Entity Effect Current (unchanged)
0x38 0x3B Resource Pack Send Current Pre
0x39 0x3C Respawn Current (unchanged)
0x3A 0x3D Entity Head Look Current (unchanged)
0x3B 0x3E Multi Block Change Current (unchanged)
0x3C 0x3F Select Advancement Tab Current (unchanged)
0x40 Action Bar Pre
0x41 World Border Center Pre
0x42 World Border Lerp Size Pre
0x43 World Border Size Pre
0x44 World Border Warning Delay Pre
0x45 World Border Warning Reach Pre
0x3E 0x46 Camera Current (unchanged)
0x3F 0x47 Held Item Change (clientbound) Current (unchanged)
0x40 0x48 Update View Position Current (unchanged)
0x41 0x49 Update View Distance Current (unchanged)
0x42 0x4A Spawn Position Current Pre
0x43 0x4B Display Scoreboard Current (unchanged)
0x44 0x4C Entity Metadata Current (unchanged)
0x45 0x4D Attach Entity Current (unchanged)
0x46 0x4E Entity Velocity Current (unchanged)
0x47 0x4F Entity Equipment Current (unchanged)
0x4F Title Current
0x48 0x50 Set Experience Current (unchanged)
0x49 0x51 Update Health Current (unchanged)
0x4A 0x52 Scoreboard Objective Current (unchanged)
0x4B 0x53 Set Passengers Current (unchanged)
0x4C 0x54 Teams Current (unchanged)
0x4D 0x55 Update Score Current (unchanged)
0x56 Set Title SubTitle Pre
0x4E 0x57 Time Update Current (unchanged)
0x58 Set Title Text Pre
0x59 Set Title Time Pre
0x50 0x5A Entity Sound Effect Current (unchanged)
0x51 0x5B Sound Effect Current (unchanged)
0x52 0x5C Stop Sound Current (unchanged)
0x53 0x5D Player List Header And Footer Current (unchanged)
0x54 0x5E NBT Query Response Current (unchanged)
0x55 0x5F Collect Item Current (unchanged)
0x56 0x60 Entity Teleport Current (unchanged)
0x57 0x61 Advancements Current (unchanged)
0x58 0x62 Entity Properties Current Pre
0x59 0x63 Entity Effect Current (unchanged)
0x5A 0x64 Declare Recipes Current (unchanged)
0x5B 0x65 Tags Current Pre
Play serverbound
0x05 Client Settings Current Pre
Handshaking serverbound
0x00 Handshake Current Pre

New/modified data types

No changes so far.

Entity Metadata

Warning.png Note that other entities have had metadata shifts due to these changes, not shown here.

Entity

The base class.

Index Type Meaning Default
0 Byte Bit mask Meaning 0
0x01 Is on fire
0x02 Is crouching
0x04 Unused (previously riding)
0x08 Is sprinting
0x10 Is swimming
0x20 Is invisible
0x40 has glowing effect
0x80 Is flying with an elytra
1 VarInt Air ticks 300
2 OptChat Custom name empty
3 Boolean Is custom name visible false
4 Boolean Is silent false
5 Boolean Has no gravity false
6 Pose Pose STANDING
7 VarInt Ticks frozen in powdered snow 0

Block Actions

No changes so far.

Inventories

No changes so far.

Plugin Channels

No changes so far.

Play

Clientbound

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.

Clear Titles

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

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;
}

Chunk Data

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 Update Block Entity later).

Packet ID State Bound To Field Name Field Type Notes
0x20 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)
Full chunk Boolean See Chunk Format
Primary Bit Mask VarInt Bitmask with bits set to 1 for every 16×16×16 chunk section whose data is included in Data. The least significant bit represents the chunk section at the bottom of the chunk column (from y=0 to y=15).
Bit Mask Length VarInt Length of the following array
Primary Bit Mask Array of Long BitSet with bits (world height in blocks / 16) set to 1 for every 16×16×16 chunk section whose data is included in Data. The least significant bit represents the chunk section at the bottom of the chunk column (from the lowest y to 15 blocks above).
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 at 9 bits per entry totaling 36 longs). 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.
Biomes length Optional VarInt Size of the following array; should always be 1024. Not present if full chunk is false.
Biomes Optional Array of VarInt 1024 biome IDs, ordered by x then z then y, in 4×4×4 blocks. Not present if full chunk is false. See Chunk Format § Biomes.
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 entities Array of NBT Tag All block entities in the chunk. Use the x, y, and z tags in the NBT to determine their positions.

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

Entity Movement

This packet may be used to initialize an entity.

For player entities, either this packet or any move/look packet is sent every game tick. So the meaning of this packet is basically that the entity did not move/look since the last such packet.

Packet ID State Bound To Field Name Field Type Notes
0x2A Play Client Entity ID VarInt

Update Light

Updates light levels for a chunk.

Packet ID State Bound To Field Name Field Type Notes
0x23 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 VarInt Mask containing 18 bits, with the lowest bit corresponding to chunk section -1 (in the void, y=-16 to y=-1) and the highest bit for chunk section 16 (above the world, y=256 to y=271)
Block Light Mask VarInt Mask containing 18 bits, with the same order as sky light
Empty Sky Light Mask VarInt Mask containing 18 bits, which indicates sections that have 0 for all their sky light values. If a section is set in both this mask and the main sky light mask, it is ignored for this mask and it is included in the sky light arrays (the notchian server does not create such masks). If it is only set in this mask, it is not included in the sky light arrays.
Empty Block Light Mask VarInt Mask containing 18 bits, which indicates sections that have 0 for all their block light values. If a section is set in both this mask and the main block light mask, it is ignored for this mask and it is included in the block light arrays (the notchian server does not create such masks). If it is only set in this mask, it is not included in the block light arrays.
Length 1 VarInt Length of the following array
Sky Light Mask Array of Long BitSet containing bits for each sections in the world + 2 (lowest bit 16-1 blocks below min world height, highest 1-16 above max world height)
Length 2 VarInt Length of the following array
Block Light Mask Array of Long BitSet containing bits for each sections in the world + 2, same order as sky light
Length 3 VarInt Length of the following array
Empty Sky Light Mask Array of Long BitSet containing a variable amount of bits (see sky/block light) which indicates sections that have 0 for all their sky light values
Length 4 VarInt Length of the following array
Empty Block Light Mask Array of Long BitSet containing a variable amount of bits (see sky/block light) which indicates sections that have 0 for all their block light values
Sky Light array count VarInt Number of entries in the following array
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
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.


Map Data

Updates a rectangular area on a map item.

Packet ID State Bound To Field Name Field Type Notes
0x25 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)
Tracking Position Boolean Specifies whether player and item frame icons are shown
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 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

Combat Event

Originally used for metadata for twitch streaming circa 1.8. Now only used to display the game over screen (with enter combat and end combat completely ignored by the Notchain client)

Packet ID State Bound To Field Name Field Type Notes
0x31 Play Client Event VarInt Enum Determines the layout of the remaining packet.
Event Field Name
0: enter combat no fields no fields
1: end combat Duration VarInt 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.
2: entity dead Player ID VarInt Entity ID of the player that died (should match the client's entity ID).
Entity ID Int The killing entity's ID, or -1 if there is no obvious killer.
Message Chat The death message.

End Combat Event

Unused by the Notchain client.

Packet ID State Bound To Field Name Field Type Notes
0x32 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.

Packet ID State Bound To Field Name Field Type Notes
0x33 Play Client


Death Combat Event

Used to send a respawn screen.

Packet ID State Bound To Field Name Field Type Notes
0x34 Play Client Player ID VarInt Entity ID of the player that died (should match the client's entity ID).
Entity ID Int The killing entity's ID, or -1 if there is no obvious killer.
Message Chat The death message.

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
0x34 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

Destroy Entity

Sent by the server when a list of entities an entity is to be destroyed on the client.

Packet ID State Bound To Field Name Field Type Notes
0x36 Play Client
Count VarInt Number of elements in the following array.
Array of VarInt The list of entities of destroy.
Entity ID VarInt

Resource Pack Send

Packet ID State Bound To Field Name Field Type Notes
0x38 0x3B 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.
Forced Message Chat This is sent with the force resourcepack popup.

Title

Packet ID State Bound To Field Name Field Type Notes
0x4F Play Client Action VarInt Enum
Action Field Name
0: set title Title Text Chat
1: set subtitle Subtitle Text Chat
2: set action bar Action bar text Chat Displays a message above the hotbar (the same as position 2 in Chat Message (clientbound).
3: set times and display 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.
4: hide no fields no fields
5: reset no fields no fields

“Hide” makes the title disappear, but if you run times again the same title will appear. “Reset” erases the text.

The title is visible on screen for Fade In + Stay + Fade Out ticks.

Action Bar

Packet ID State Bound To Field Name Field Type Notes
0x40 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
0x41 Play Client X Double
Z Double

World Border Lerp Size

Packet ID State Bound To Field Name Field Type Notes
0x42 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
0x43 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
0x44 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
0x45 Play Client Warning Blocks VarInt In meters.

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
0x42 0x4B Play Client Location Position Spawn location.
Angle Float

Set Title SubTitle

Packet ID State Bound To Field Name Field Type Notes
0x56 Play Client Subtitle Text Chat


Set Title Text

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

Set Title Time

Packet ID State Bound To Field Name Field Type Notes
0x59 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 Properties

Sets attributes on the given entity.

Packet ID State Bound To Field Name Field Type Notes
0x58 0x63 Play Client Entity ID VarInt
Number Of Properties Int 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.

Tags

Packet ID State Bound To Field Name Field Type Notes
0x5B 0x65 Play Client
Block Tags (See below) IDs are block IDs
Item Tags (See below) IDs are item IDs
Fluid Tags (See below) IDs are fluid IDs
Entity Tags (See below) IDs are entity IDs
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.).


Serverbound

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.
Displayed Skin Parts Unsigned Byte Bit mask, see below.
Main Hand VarInt Enum 0: Left, 1: Right.
Disable text filtering Boolean Disables filtering of text on signs and written book titles. Currently always true (i.e. the filtering is disabled)

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.


Window Confirmation (serverbound)

If a confirmation sent by the client was not accepted, the server will reply with a Window Confirmation (clientbound) packet with the Accepted field set to false. When this happens, the client must send this packet to apologize (as with movement), otherwise the server ignores any successive confirmations.

Packet ID State Bound To Field Name Field Type Notes
0x07 Play Server Window ID Byte The ID of the window that the action occurred in.
Action Number Short Every action that is to be accepted has a unique number. This number is an incrementing integer (starting at 1) with separate counts for each window ID.
Accepted Boolean Whether the action was accepted.

Handshaking

Clientbound

There are no clientbound packets in the Handshaking state, since the protocol immediately switches to a different state after the client sends the first packet.

Serverbound

Handshake

This causes the server to switch into the target state.

Packet ID State Bound To Field Name Field Type Notes
0x00 Handshaking Server Protocol Version VarInt See protocol version numbers (currently 754 Snapshot 15)
Server Address String Hostname or IP, e.g. localhost or 127.0.0.1, that was used to connect. The Notchian server does not use this information. Note that SRV records are a complete simple redirect, e.g. if _minecraft._tcp.example.com points to mc.example.org, users connecting to example.com will provide mc.example.org as server address in addition to connecting to it.
Server Port Unsigned Short Default is 25565. The Notchian server does not use this information.
Next State VarInt Enum 1 for status, 2 for login

Status

Clientbound

No changes so far.

Serverbound

No changes so far.

Login

Clientbound

No changes so far.

Serverbound

No changes so far.