Development resources

Quatroking butthurt much?

 Quatroking butthurt much?

 Quatroking butthurt much?

 Quatroking butthurt much?

 Quatroking butthurt much?

 Quatroking butthurt much?

 Quatroking butthurt much?

Packet Protocol

Every packet starts with a byte representing the Packet ID.

Protocol Data Types

Type	Size [bytes]	Description
Byte	1	Single byte integer (0 to 255)
SByte	1	Single byte signed integer (-128 to 127)
Short	2	Signed integer, network order (-32768 to 32767)
String	64	US-ASCII/ISO646-US encoded string padded with spaces (0x20)
Byte array	1024	Binary data padded with null bytes (0x00)

Client → Server packets

Packet ID	Purpose	Field Description	Field Type	Notes
0x00	Player Identification	Packet ID	Byte	Sent by a player joining a server with relevant information. Current protocol version is 0x07.
		Protocol version	Byte
		Username	String
		Verification key	String
		Unused	Byte
0x05	Set Block	Packet ID	Byte	Sent when a user changes a block. The mode field indicates whether a block was created (0x01) or destroyed (0x00). Block type is always the type player is holding, (even when deleting). Client assumes that this command packet always succeeds, and so draws the new block immediately. To disallow block creation, server must send back Set Block packet with the old block type. The XYZ coordinates of the block are just integers representing the coordinate of the block. (As opposed to player coordinates where the lower 5 bits are fractional coordinates)
		X	Short
		Y	Short
		Z	Short
		Mode	Byte
		Block type	Byte
0x08	Position and Orientation	Packet ID	Byte	Sent frequently (even while not moving) by the player with the player's current location and orientation. Player ID is always 255, referring to itself. Player coordinates are fixed-point values with the lowest 5 bits representing the fractional position (i.e. divide by 32 to get actual position in terms of block coordinates). The angle parameters are scaled such that a value of 256 would correspond to 360 degrees.
		Player ID	Byte
		X	Short
		Y	Short
		Z	Short
		Heading	Byte
		Pitch	Byte
0x0d	Message	Packet ID	Byte	Contain chat messages sent by player.
		Unused	Byte (0xFF)
		Message	String

Server → Client packets

Packet ID	Purpose	Field Description	Field Type	Notes
0x00	Server Identification	Packet ID	Byte	Response to a joining player. The user type indicates whether a player is an op (0x64) or not (0x00) Current protocol version is 0x07.
		Protocol version	Byte
		Server name	String
		Server MOTD	String
		User type	Byte
0x01	Ping	Packet ID	Byte	Sent to clients periodically. The only way a client can disconnect at the moment is to force it closed, which does not let the server know. The ping packet is used to determine if the connection is still open.
0x02	Level Initialize	Packet ID	Byte	Notifies player of incoming level data.
0x03	Level Data Chunk	Packet ID	Byte	Contains a chunk of gzipped map (not level.dat file). After decompression the map consists of a int(4 bytes) containing number of blocks + raw map array. (chunk is up to 1024 bytes, padded with 0x00s if less).
		Chunk Length	Short
		Chunk Data	Byte Array
		Percent Complete	Byte
0x04	Level Finalize	Packet ID	Byte	Sent after level data is complete and gives map dimensions. The y coordinate is how tall the map is.
		X Size	Short
		Y Size	Short
		Z Size	Short
0x06	Set Block	Packet ID	Byte	Sent to indicate a block change by physics or by players. In the case of a player change, the server will also echo the block change back to the player who initiated it.
		X	Short
		Y	Short
		Z	Short
		Block Type	Byte
0x07	Spawn Player	Packet ID	Byte	Sent to indicate where a new player is spawning in the world. Position and orientation are encoded the same as for packet 0x08 below.
		Player ID	Byte
		Player Name	String
		X	Short
		Y	Short
		Z	Short
		Heading	Byte
		Pitch	Byte
0x08	Player Teleport / Position and Position and Orientation Update	Packet ID	Byte	Sent with changes in player position and rotation. Teleports player it's sent to if player ID = 0xFF (For sending initial position in map, and /tp)
		Player ID	Byte
		X	Short
		Y	Short
		Z	Short
		Heading	Byte
		Pitch	Byte
0x09	Position and Orientation Update	Packet ID	Byte	Sent with changes in player position and rotation. Not fully understood, or required for server operation.
		Player ID	Byte
		X	SByte
		Y	SByte
		Z	SByte
		Heading	Byte
		Pitch	Byte
0x0a	Position Update	Packet ID	Byte	Sent with changes in player position. Not required for server operation.
		Player ID	Byte
		Change in X	SByte
		Change in Y	SByte
		Change in Z	SByte
0x0b	Orientation Update	Packet ID	Byte	Sent with changes in player rotation. Not required for server operation.
		Player ID	Byte
		Heading	Byte
		Pitch	Byte
0x0c	Despawn Player	Packet ID	Byte	Sent when player disconnects.
		Player ID	Byte
0x0d	Message	Packet ID	Byte	Messages sent by chat or from the console.
		Player ID	Byte
		Message	String
0x0e	Disconnect player	Packet ID	Byte	Sent to a player when they're disconnected from the server. "Cheat detected: Distance" - happens not only when setting tile too far away from the player (how far is maximum distance and how it is measured?), but also when player moves and then immediately builds. "Cheat detected: Tile type"
		Disconnect reason	String
0x0f	Update user type	Packet ID	Byte	Sent when a player is opped/deopped
		User type	Byte

Color Codes

Messages sent from the server to the client can contain color codes, which allow coloring of text for various purposes. An ampersand followed by a hex digit in the message tells the client to switch colors while displaying text. Colour coding at the start of the message will only work if the player ID byte is less than 127. If it's 127 or higher, the game automatically adds &e before the message, making it yellow. However, colour codes after the first character still work. If you use an ID below 127, it doesn't add a colour code, so the ones you use will work.

Hex digit to color mapping

Sample	Code	Common Name	Foreground Color			Background Color
			R	G	B	R	G	B
	&0	Black	0	0	0	0	0	0
	&1	Dark Blue	0	0	191	0	0	47
	&2	Dark Green	0	191	0	0	47	0
	&3	Dark Teal	0	191	191	0	47	47
	&4	Dark Red	191	0	0	47	0	0
	&5	Purple	191	0	191	47	0	47
	&6	Dark Yellow	191	191	0	47	47	0
	&7	Gray	191	191	191	47	47	47
	&8	Dark Gray	40	40	40	16	16	16
	&9	Blue	64	64	255	16	16	63
	&a	Bright Green	64	255	64	16	63	16
	&b	Teal	64	255	255	16	63	63
	&c	Red	255	64	64	63	16	16
	&d	Pink	255	64	255	63	16	63
	&e	Yellow	255	255	64	63	63	16
	&f	White	255	255	255	63	63	63

Mobs

See also: Mobs

In multiplayer creative mode, all mobs are treated the same by the client. To create non-player mobs, simply send updates for them as you would a normal player. The client finds a mob's skin by its name, downloading from http://minecraft.net/skin/name.png and defaulting to the generic mob if it doesn't exist. To give your monsters a special skin, you would need to register and pay for an account with the monster's name.

You can also send fake names for actual players in order to force them to have a certain skin.

Resources

Programs

URL	Program	OS	Notes
http://www.delorie.com/djgpp/	Djgpp, GCC for windows	Windows
http://www.cygwin.com/	Cygwin the Linux-on-Windows (Unix Environment)	Windows	Good for Windows users.
http://www.microsoft.com/express/	Microsoft Visual Studio Express	Windows	Free version of Visual Studio, an IDE and compiler for C/++, C# and Visual Basic.
http://java.sun.com/javase/downloads/index.jsp	Java Development Kit download	Cross-platform	Essential if you want to compile Java code