CLIENTBOUND.md

Clientbound Packets

Encodings

Name	Description	Size
Float	A floating point number	4
Varint	A signed 32 bit integer	1+
Varuint	An unsigned 32 bit integer	1+
String	A null terminated string	1+

You might've noticed that only four out of the six primary encodings are used on clientbound packets. Varfloats and Ints are only used on serverbound packets. However, the client do have a few secondary encodings, as listed below.

Name	Description	Structure
Entity Id	The id of an entity.	vu(time) vu(counter)
Varindex	The index of a field.	vu(index XOR 1)

Fields

In diep, there is a table of fields, with each row mapped to an index and a type, which looks like this:

Index	Type	Description
1	vi	Angle
2	vi	X-position
3	vi	Y-position
5	f	Max Health
24	f	Health

Example

Here is a example of a packet where two entities are deleted while one is being updated:

00          | vu 0      | header
20          | vu 32     | packet id
02          | vu 2      | number deleted
   01 04    | ei 1:4    | entity 1:4
   01 06    | ei 1:6    | entity 1:6
01          | vu 3      | number created or updated
   01 07    | ei 1:2    | entity 1:7
      00 01 | vu 0 vu 1 | updating mode
      00    | vx 1      | field id (= 1)
      a2 02 | vi ???    | field 1: x
      00    | vx 1      | field id (= 1 + 1)
      fc 01 | vi ???    | field 2: y
      00    | vx 1      | field id (= 1 + 1 + 1)
      73    | vi ???    | field 3: angle
      01    | vx 0      | field ended

Compression

Diep.io uses a modified version of LZ4. There are no magic numbers or checksum at the start. Instead, following the packet header is a 32-bit integer denoting the byte length of the decompressed 00 packet, and the compressed 00 packet itself.