bot._client.on 'sync_entity_position' changes entity.pitch and entity.yaw to wrong value

[seeeebaaaa]

• The FAQ doesn't contain a resolution to my issue

Versions

• mineflayer: 4.27.0
• server: vanilla 1.21.4
• node: v23.5.0

Detailed description of a problem

The pitch and yaw of an entity (in this case another player) doesn't get updated correctly, when the client receives sync_entity_position. (Seems to be send when the entity/player jumps or moves down from a block)
The pitch and yaw gets corrected, once the entity looks somewhere else and the entity_look or entity_move_look packages are processed.
This makes accurate tracking of the looking direction of e.g. a player impossible.

Minimal example

const mineflayer = require('mineflayer')

const bot = mineflayer.createBot({
  host: 'localhost',
  username: 'Bot',
  auth: 'offline',
  port: 50622,
  version: '1.21.4'
})

bot.on('physicTick', _ => {
  const nearestPlayer = bot.nearestEntity(entity => entity.type === 'player')
  if (nearestPlayer) {
    console.log("Yaw:",nearestPlayer.yaw, " Pitch:",nearestPlayer.pitch)
  } else {
    console.log('No nearby players found.')
  }
})

This will log something like this.:

...
Yaw: 4.3933209765044765  Pitch: 0.09817477042468115
Yaw: 4.3933209765044765  Pitch: 0.09817477042468115
Yaw: 4.3933209765044765  Pitch: 0.09817477042468115 
Yaw: -71.379150390625  Pitch: -5.099963665008545
Yaw: -71.379150390625  Pitch: -5.099963665008545
...
Yaw: -71.379150390625  Pitch: -5.099963665008545
Yaw: -71.379150390625  Pitch: -5.099963665008545
Yaw: 4.663301595172349  Pitch: 0.07363107781851097
Yaw: 4.663301595172349  Pitch: 0.07363107781851097
Yaw: 4.663301595172349  Pitch: 0.07363107781851097
...

The first change (to -71 and -5) happened after the player pressed space to jump, and the second change (back to (4 and 0) happened after the player moved the mouse aka. looked around.

Expected behavior

The yaw and pitch should not change when jumping or moving down blocks / when that package gets send.

Possible Solution

I don't know what exactly the package sync_entity_position does, but it appears that the send yaw and pitch are neither radians nor the notchianYawBytes, but degrees instead (as seen in the F3 Debug menu). So they need to be converted into radians before being written to the entity.yaw and entity.pitch.

So the current code:

mineflayer/lib/plugins/entities.js

Lines 345 to 353 in 2b6bd7d

	// 1.21.3 - merges the packets above
	bot._client.on('sync_entity_position', (packet) => {
	const entity = fetchEntity(packet.entityId)
	entity.position.set(packet.x, packet.y, packet.z)
	entity.velocity.update(packet.dx, packet.dy, packet.dz)
	entity.yaw = packet.yaw
	entity.pitch = packet.pitch
	bot.emit('entityMoved', entity)
	})

Should be modified like this:

// 1.21.3 - merges the packets above
  bot._client.on('sync_entity_position', (packet) => {
    const entity = fetchEntity(packet.entityId)
    entity.position.set(packet.x, packet.y, packet.z)
    entity.velocity.update(packet.dx, packet.dy, packet.dz)
    entity.yaw = ((-packet.yaw)+180)* Math.PI/180
    entity.pitch = -(packet.pitch* Math.PI/180)
    bot.emit('entityMoved', entity)
  })

That way the log from above will look something like this:

Yaw: 4.466952054322987  Pitch: 0.04908738521234035
Yaw: 4.466952054322987  Pitch: 0.04908738521234035
Yaw: 4.447611113222395  Pitch: 0.044505254270480264
Yaw: 4.447611113222395  Pitch: 0.044505254270480264

There is still a change in the yaw and pitch, but I think that's just because of the conversion from degree to radians and should be tolerable.

I also don't know if and how this affects 1.21.3 as it seems that that function was created for 1.21.3 specifically but apparently gets used by 1.21.4 as well.