There are several problems that were solved:
1. Spectating failed to follow players through cross-region/cross-world
teleporting.
2. Inability to set camera to off-region entity
3. Various crashes involved with off-region camera entity
4. Spectator does not always follow entities through portals
We fix#1 by sending ClientboundSetCameraPacket when the spectated
entity becomes in tracked, as the client appears to be unable to
correctly handle when the camera entity is removed, even temporarily.
We fix#2 by allowing off-region entities that are not dead.
However, this required the teleportation code in both setCamera
and the ServerPlayer#tick method to be modified to correctly
handle off-region camera targets.
We fix#3 by correctly teleporting to off-region locations
when needed.
We fix#4 by following the Bukkit entity. This allows spectator
mode to properly follow non-player entities through portals.
Issues #1 (cross-world) and #4 are probably present in Paper/Vanilla, however
solving #2 and #3 required a solution for these.
Fixes https://github.com/PaperMC/Folia/issues/324
Instead of relying on COLLISION_FLAG_COLLIDE_WITH_UNLOADED_CHUNKS,
we will force a chunk not owned by the current region to collide
so that entities moving at high speed cannot move out of region.
The owner of the projectile would need to be retrieved, which
may trip a thread check. We do not track ender pearls anyways,
so the registration logic does nothing regardless.
Fixes https://github.com/PaperMC/Folia/issues/315
We cannot guarantee that the current region owns the chunk
associated with the ChunkData. As a result, more than 1 region
may write to the field.
Additionally, we did not include any logic to adjust the field during
a region merge or split - which would leave invalid data in the field.
As a result, the nearbyPlayers data retrieved from the ChunkData
was possibly invalid which may have lead to entity tracker desync
problems.
Fixes https://github.com/PaperMC/Folia/issues/317
It is possible that when the reference count is retrieved that
the ticket updates have not yet been processed, which means
that the region section at the queued position may not exist or may
become nonexistant while or after the task is being added.
This restructures the reference counting code to now refer to
both a reference counter and a flag indicating whether ticket
updates are processed.
Fixes https://github.com/PaperMC/Folia/issues/262
This issue shows the race condition where the region becomes
nonexistant.
If we cannot find a spawn pos in the spawn radius,
use the same fallback logic as when the world type or player's
gamemode does not support spawn selection. This adjusts the spawn
position to not be inside a wall or on water.
The spawn selection may actually be farther than 32 blocks,
so we need a larger load radius to prevent a deadlock on startup.
Additionally, re-insert thread checks for sync loads that were
previously in 1.20.
If a player moves away before the raid is created, then we would
possibly trigger the raid cross-region.
Considering Vanilla doesn't trigger the raid cross-dimension, this
doesn't seem like an important behavior to break.
Fixes https://github.com/PaperMC/Folia/issues/264
CraftEntity properly tracks the underlying entity handle
when the entity teleports. This resolves a race condition
where if an enderpearl was ticked while its owner was teleporting,
the owner reference would be lost.
Fixes https://github.com/PaperMC/Folia/issues/279
This field is covered by the entity tracker optimisations in Paper,
but currently was not properly maintained - resulting in memory leaks.
Fixes https://github.com/PaperMC/Folia/issues/283
