Small movements may not trigger PlayerMoveEvent until the player rotates

[minijaham]

Plugin information

Bug happens without plugins

Problem description

Steps to reproduce:

1. Listen for PlayerMoveEvent
2. Write code to dump X and Z coordinates of PlayerMoveEvent::getFrom() and PlayerMoveEvent::getTo()
3. Don't move, but only rotate the player

Plugin Code

public function onPlayerMove(PlayerMoveEvent $event) : void
{
    $player = $event->getPlayer();

    $from = $event->getFrom()->asPosition();
    $to   = $event->getTo()->asPosition();

    var_dump("FROM");
    var_dump($from->x);
    var_dump($from->y);
    var_dump($from->z);
    
    var_dump("");

    var_dump("TO");
    var_dump($to->x);
    var_dump($to->y);
    var_dump($to->z);
}

Results
string(4) "FROM"
float(-829.7068)
float(67)
float(1219.9551)

string(2) "TO"
float(-829.7025)
float(67)
float(1219.9567)

As you can see, there are subtle differences in the player's X and Z position.

I'm not entirely sure if this is an expected behavior, though. I have performed some researches, but couldn't find an issue related with this behavior specifically.

Expected behaviour

The X and Z position should be the same when rotating the player.

PocketMine-MP version

5.23.2

PHP version

8.2.17

Server OS

win

Game version (if applicable)

Windows

[dktapps]

It's probably because of this:

PocketMine-MP/src/player/Player.php

Line 1378 in fbaa125

if($delta > 0.0001 || $deltaAngle > 1.0){

There can be a difference in position unreported by PlayerMoveEvent if the distance is below 0.01 blocks. Rotation bypasses this check since PlayerMoveEvent reports both position and rotation.

It's definitely not ideal behaviour but I'm not sure how it could be done better. The reason it's done this way is to make sure we aren't spamming the event whenever a player sends any movement at all.

[dries-c]

Ideally the event listener would specify how precise they want the event to change before getting called (for example allow only vector3 movements without rotation etc). But that's hard to deal with on the PM side. You would expect all rotations to call a PlayerMoveEvent regardless of how much they move.

[dktapps]

I've considered splitting it into two events before. But I doubt it would have much benefit (and might have negative consequences in stuff like PvP servers).

Perhaps what we need to do is just always dispatch an event if there was no new movement processed on the current tick, so that plugins always have the latest position.