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

Class MobSpawnEvent

java.lang.Object

net.neoforged.bus.api.Event

net.neoforged.neoforge.event.entity.EntityEvent

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

Direct Known Subclasses:

FinalizeSpawnEvent, MobDespawnEvent, MobSpawnEvent.PositionCheck

public abstract class MobSpawnEvent
extends EntityEvent

This class holds all events relating to the entire flow of mob spawns.
Currently, the events have the following flow for any given mob spawn:

Before the spawn is attempted MobSpawnEvent.SpawnPlacementCheck is fired, to determine if the spawn may occur based on mob-specific rules.
After the entity is created MobSpawnEvent.PositionCheck is fired, to determine if the selected position is legal for the entity.
If both checks succeeded,

invalid reference

FinalizeSpawn

is fired, which performs initialization on the newly-spawned entity.
Finally, if the spawn was not cancelled via

invalid reference

FinalizeSpawn#setSpawnCancelled

, then EntityJoinLevelEvent is fired as the entity enters the world.

invalid reference

AllowDespawn

is not related to the mob spawn event flow, as it fires when a despawn is attempted.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	MobSpawnEvent.PositionCheck	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.
static class	MobSpawnEvent.SpawnPlacementCheck	This event is fired when Spawn Placements (aka Spawn Rules) are checked, before a mob attempts to spawn. Spawn Placement checks include light levels, slime chunks, grass blocks for animals, and others in the same vein. The purpose of this event is to permit runtime changes to any or all spawn placement logic without having to wrap the placement for each entity.

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

EntityEvent.EnteringSection, EntityEvent.EntityConstructing, EntityEvent.Size

Field Summary

Fields

Modifier and Type	Field	Description
private final ServerLevelAccessor	level
private final double	x
private final double	y
private final double	z

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	MobSpawnEvent(Mob mob, ServerLevelAccessor level, double x, double y, double z)

Method Summary

Modifier and Type	Method	Description
Mob	getEntity()
ServerLevelAccessor	getLevel()
double	getX()
double	getY()
double	getZ()

Methods inherited from class java.lang.Object

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

Field Details

level

private final ServerLevelAccessor level

x

private final double x

y

private final double y

z

private final double z

Constructor Details

MobSpawnEvent

@Internal
protected MobSpawnEvent(Mob mob,
 ServerLevelAccessor level,
 double x,
 double y,
 double z)

Method Details

getEntity

public Mob getEntity()

Overrides:

getEntity in class EntityEvent

getLevel

public ServerLevelAccessor getLevel()

Returns:

The level relating to the mob spawn action

getX

public double getX()

Returns:

The x-coordinate relating to the mob spawn action

getY

public double getY()

Returns:

The y-coordinate relating to the mob spawn action

getZ

public double getZ()

Returns:

The z-coordinate relating to the mob spawn action