Package net.neoforged.neoforge.event.entity.living

Class MobSpawnEvent.PositionCheck

java.lang.Object

net.neoforged.bus.api.Event

net.neoforged.neoforge.event.entity.EntityEvent

net.neoforged.neoforge.event.entity.living.MobSpawnEvent

net.neoforged.neoforge.event.entity.living.MobSpawnEvent.PositionCheck

Enclosing class:

MobSpawnEvent

public static class MobSpawnEvent.PositionCheck
extends MobSpawnEvent

This event is fired when a mob checks for a valid spawn position, after SpawnPlacements.checkSpawnRules(net.minecraft.world.entity.EntityType<T>, net.minecraft.world.level.ServerLevelAccessor, net.minecraft.world.entity.MobSpawnType, net.minecraft.core.BlockPos, net.minecraft.util.RandomSource) has been evaluated.
Conditions validated here include the following:

• Obstruction - mobs inside blocks or fluids.
• Pathfinding - if the spawn block is valid for pathfinding.
• Sea Level - Ocelots check if the position is above sea level.
• Spawn Block - Ocelots check if the below block is grass or leaves.

These checks are performed by the vanilla methods Mob.checkSpawnRules(net.minecraft.world.level.LevelAccessor, net.minecraft.world.entity.MobSpawnType) and Mob.checkSpawnObstruction(net.minecraft.world.level.LevelReader).
The logical-and of both methods forms the default result of this event.

This event has a result.
To change the result of this event, use Event.setResult(net.neoforged.bus.api.Event.Result). Results are interpreted in the following manner:

• Allow - The position will be accepted, and the spawn process will continue.
• Default - The position will be accepted if Mob.checkSpawnRules(net.minecraft.world.level.LevelAccessor, net.minecraft.world.entity.MobSpawnType) and Mob.checkSpawnObstruction(net.minecraft.world.level.LevelReader) are both true.
• Deny - The position will not be accepted. The spawn process will abort, and further events will not be called.

This event is fired on the main Forge event bus, only on the logical server.

API Note:

This event fires after Spawn Placement checks, which are the primary set of spawn checks.

Nested Class Summary

Nested classes/interfaces inherited from class net.neoforged.neoforge.event.entity.living.MobSpawnEvent

MobSpawnEvent.AllowDespawn, MobSpawnEvent.FinalizeSpawn, MobSpawnEvent.PositionCheck, MobSpawnEvent.SpawnPlacementCheck

Nested classes/interfaces inherited from class net.neoforged.neoforge.event.entity.EntityEvent

EntityEvent.EnteringSection, EntityEvent.EntityConstructing, EntityEvent.Size

Nested classes/interfaces inherited from class net.neoforged.bus.api.Event

net.neoforged.bus.api.Event.HasResult, net.neoforged.bus.api.Event.Result

Field Summary

Fields

Modifier and Type	Field	Description
private final @Nullable BaseSpawner	spawner
private final MobSpawnType	spawnType

Constructor Summary

Constructors

Constructor	Description
PositionCheck(Mob mob, ServerLevelAccessor level, MobSpawnType spawnType, @Nullable BaseSpawner spawner)

Method Summary

Modifier and Type	Method	Description
@Nullable BaseSpawner	getSpawner()	Retrieves the underlying BaseSpawner instance if this mob was created by a Mob Spawner of some form.
MobSpawnType	getSpawnType()	Retrieves the type of mob spawn that is happening.

Methods inherited from class net.neoforged.neoforge.event.entity.living.MobSpawnEvent

getEntity, getLevel, getX, getY, getZ

Methods inherited from class net.neoforged.bus.api.Event

getResult, hasResult, setResult

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Details

spawner

@Nullable
private final @Nullable BaseSpawner spawner

spawnType

private final MobSpawnType spawnType

Constructor Details

PositionCheck

public PositionCheck(Mob mob,
 ServerLevelAccessor level,
 MobSpawnType spawnType,
 @Nullable
 @Nullable BaseSpawner spawner)

Method Details

getSpawner

@Nullable
public @Nullable BaseSpawner getSpawner()

Retrieves the underlying BaseSpawner instance if this mob was created by a Mob Spawner of some form. This is always null unless getSpawnType() is MobSpawnType.SPAWNER, and may still be null even then.

Returns:

The BaseSpawner responsible for triggering the spawn, or null if none is available.

getSpawnType

public MobSpawnType getSpawnType()

Retrieves the type of mob spawn that is happening.

Returns:

The mob spawn type.

See Also:

• MobSpawnType