Mob AI

This article describes the various components of a mob's AI that control the mob's behavior.

Some mobs use a complex AI system called a brain. A mob's brain stores memories (data), a list of tasks that can be performed, and a list of sensors used to determine which tasks it can perform.

Sensors are used to detect if a mob with a brain can perform certain tasks. Examples of sensors include, a sensor to detect if an armadillo should be scared, a sensor to detect the nearest player, and a sensor to detect if a mob is in water.

List of Sensor in Java Edition

Sensor	Class	Uses
dummy	DummySensor	defaulted sensor type
nearest_items	NearestItemSensor	Allay Goat Piglin Piglin Brute Villager
nearest_living_entities	NearestLivingEntitySensor	Allay Armadillo Axolotl Breeze Camel Copper Golem Creaking Frog Goat Happy Ghast Hoglin Nautilus Piglin Piglin Brute Sniffer Tadpole Villager Zoglin Zombie Nautilus
nearest_players	PlayerSensor	Allay Breeze Creaking Goat Happy Ghast Hoglin Nautilus Piglin Piglin Brute Sniffer Tadpole Villager Warden Zoglin Zombie Nautilus
nearest_bed	NearestBedSensor	Villager
hurt_by	HurtBySensor	Allay Armadillo Axolotl Breeze Camel Copper Golem Frog Goat Happy Ghast Nautilus Piglin Piglin Brute Sniffer Tadpole Villager Zombie Nautilus
villager_hostiles	VillagerHostilesSensor	Villager
villager_babies	VillagerBabiesSensor	Villager
secondary_pois	SecondaryPoiSensor	Villager
golem_detected	GolemSensor	Villager
armadillo_scare_detected	MobSensor	Armadillo
piglin_specific_sensor	PiglinSpecificSensor	Piglin
piglin_brute_specific_sensor	PiglinBruteSpecificSensorregister	Piglin
hoglin_specific_sensor	HoglinSpecificSensor	Hoglin
nearest_adult	AdultSensor	Armadillo Axolotl Camel Goat Hoglin Nautilus Zombie Nautilus
nearest_adult_any_type	AdultSensor	Happy Ghast
axolotl_attackables	AxolotlAttackablesSensor	Axolotl
food_temptations	TemptingSensor	Armadillo Axolotl Camel Goat Happy Ghast Sniffer
frog_temptations	TemptingSensor	Frog Tadpole
nautilus_temptations	TemptingSensor	Nautilus Zombie Nautilus
frog_attackables	FrogAttackablesSensor	Frog
is_in_water	IsInWaterSensor	Frog
warden_entity_sensor	WardenEntitySensor	Warden
breeze_attack_entity_sensor	BreezeAttackEntitySensor	Breeze

Class	Memory requires	Do tick
DummySensor	None	Nothing
NearestItemSensor	nearest_visible_wanted_item	Find the nearest item that: It is to a euclidean distance of up to 32 blocks from the mob. On the y-axis, it is 16 blocks away from the mob's hitbox. It is in mob line of sight[a]. The mob wants to pick up it.[b] And save this item in the memory nearest_visible_wanted_item.
NearestLivingEntitySensor	mobs and visible_mobs	Lists all other living entities that are alive and within a cobuoid generated by the mob's hitbox incremented by mob's follow_range in all directions. Sort list by euclidean distance and add to memory mobs. In visible_mobs save the entities of mobs that[c]: They are not a Spectator player, or an invisible or marker armor stand, They are in mob line of sight[a], And they are within a range of r blocks of the mob, where r is the follow_range of the mob[d].
PlayerSensor	nearest_players, nearest_visible_player, nearest_visible_targetable_player and nearest_visible_targetable_players	List all non-spectator players to a euclidean distance up to mob's follow_range fro the mobs, sort by euclidean distance and save in nearest_players memory. From this list, it filters the players who are in the mob's line of sight[a] and within follow range[d]. If it exists, save the first player from the list in memory earest_visible_player. In memory nearest_visible_targetable_players saves this last list with the following filters: If the difficulty is peaceful, remove all players. Remove all players from creative mode. Remove all players from the same team from the mob. If the mob is the allay, remove the linked player. If the mob is a illager, minecraft:player is in the tag #illager_friends, and neither the mob nor the player is on a team, remove the player. If the mob is a tamed animal, remove their owner and the players on the owner's team. If the end list is not empty, save in memory nearest_visible_targetable_player the first player on a list.
NearestBedSensor	nearest_bed	If the mob is baby: Set the auxiliary variables triedCount = 0 and lastUpdate = GameTime + RandomInt(20)[e], where GameTime is the total number of game ticks that have elapsed in the world. In the batchCache cache, it attempts to save POIs of type home that are up to 48 blocks from the mob at a euclid distance. For each POI found whose position Pos is not in the cache, it increases triedCount by 1, if triedCount < 5, it saves (Pos, lastUpdate + 40) in the cache. In this way, it saves up to 5 new beds in the batchCache. The POIs added to the cache create a new set pois, with the position and type of each PO. Try creating a path to one of the POI in pois. If it find a path, that path can reach and the target is a POI, save the target's position in mob's memory nearest_bed. If the path cannot be found, or the path cannot be reach, and triedCount < 5, remove from the batchcache the values where the second coordinate is less than lastUpdate.
HurtBySensor	huty_by and hurt_by_entity
VillagerHostilesSensor
VillagerBabiesSensor
SecondaryPoiSensor
GolemSensor
MobSensor
PiglinSpecificSensor
PiglinBruteSpecificSensorregister
HoglinSpecificSensor
AdultSensor
AxolotlAttackablesSensor
TemptingSensor
FrogAttackablesSensor
IsInWaterSensor	is_in_water	If the mob is touching the water, add the memory is_in_water, otherwise remove the memory.
WardenEntitySensor
BreezeAttackEntitySensor

Tasks are activities that mobs with brain AI systems can perform. Sensors are used to determine if a task can be performed, and tasks may use information stored in memories. Examples of tasks include a villager walking to its jobsite, a piglin admiring an item, or a warden emerging. Tasks have priorities, so tasks with a higher priority will over run tasks with lower priority, for example, if a zombie is wandering and it sees a player, it will switch tasks to attacking.

Memories are used to store data, and are used when mobs perform tasks. Examples of memories include a list of all visible mobs in range, the location of a villager's jobsite block, and any cooldowns the mob may have.

Goals are a simple AI system used primarily by mobs already existed before the brain AI. However, there are recent mobs that use both AIs simultaneously, for example, the happy ghast.

Goals can range from wandering around, opening doors, attacking another mob, and more. Each type of mob that uses goals has its own defined list of goals, and each goal has a priority. Mobs attempt to perform the lowest priority goal they can, and may switch goals if there is an opportunity to pursue a lower priority goal. For example, if a zombie is targeting and chasing a villager (priority of 3) and a player comes within the detection range of the zombie, the zombie may target and chase the player (priority of 2) instead.

List of goals that are used by many different mobs.

List of Goals

Goal	Description	Notes
Active Target	Select an entity to target for chasing and attacking
Ambient Stand	Untamed horse bucks when player tries to ride it
Attack	Attack target
Attack with Owner	Tamed animal attacks a target mob attacked by owner
Avoid Sunlight	During day, move out of direct line-of-sight with sky
Bow Attack	Attack target with bow
Breathe Air	Mob that can drown tries to move out of water
Cat Sit on Block	Cat sits on bed, chest, or furnace
Chase Boat	Chase after boat ridden by player	Unused
Creeper Ignite	Creeper ignites
Crossbow Attack	Attack target with crossbow
Destroy Egg	Destroy turtle eggs
Disableable Follow Target	Raid entity stops following target	Unused
Dive Jump	Mob jumps up and dives down
Dolphin Jump	Dolphin jumps out of water
Door Interact	Mob tries to open a door
Eat Grass	Mob grazes on grass
Escape Danger	Mob panics and runs away when damaged
Flee Entity	Mob runs away from another mob that it is scared of (e.g. skeletons running from wolves)
Fly	Mob tries to fly
Follow Group Leader	Fish tries to follow the leader of a school of fish
Follow Mob	Mob follows another mob
Follow Owner	Tamed mob follows owner
Follow Parent	Baby mob follows its parent
Form Caravan	up to 8 llamas in caravan
Go to Bed and Sleep	Tamed cat sleeps in bed
Go to Walk Target	Mob walks to a target
Hold in Hands	Mob holds an item in its main hand
Horse Bond with Player	Horse attempts to bond with player attempting to tame it
Iron Golem Look	Iron golem looks at a villager
Iron Golem Wander Around	Iron golem wanders around village	uses points of interest
Long Door Interact	Open a door, then close it after a delay
Look Around	Mob spins around and looks in random directions
Look At Customer	Villager or wandering trader looks at player while trading
Look At Entity	Mob looks at another mob
Melee Attack	Mob paths to target and attacks
Move Into Water	Mob paths to water
Move Through Village	Mob moves between points of interest in a village
Move To Raid Center	Raiders move toward village after spawning
Move To Target Position	Mob paths to a specific block
Pounce At Target	Mob jumps towards target	cats, foxes, ocelots
Powder Snow Jump	Mob dives into powder snow	foxes
Prioritized Goal	Used to override the default priority of a goal
Projectile Attack	Mob attacks target with a projectile	arrow, spit, trident, potion, snow ball, wither skull, not fireballs
Raid Goal	Raiders target villagers
Revenge	Target entity that attacked the mob
Wander Around	Move to a nearby random position
Wander Around Far	Move to a random position, sometimes farther away than Wander Around goal
Zombie Attack	Attack goal for zombies and zombie variants

Lists of goals and associated priorities for individual mobs.

Zombie

Goal	Priority	Notes
Revenge	1	Attack entity that damaged the zombie
Active Target - Player	2	Target the player
Zombie Attack	2	Attack current target
Active Target - Iron Golem	3	Target Iron Golem
Active Target - Merchant	3	Target Villager or Wandering Trader
Destroy Egg	4	Break turtle eggs
Active Target - Turtle	5	Target baby turtle
Wander Around Far	7
Look Around	8	Looks away from Entities
Look at Entity	8	Looks at nearest Entities

When pathfinding to a target, mobs will sometimes avoid certain blocks (usually blocks that cause damage or slow the mob down). These blocks have a penalty associated with them. Generally, mobs try to path through blocks with the smallest penalty. There are some blocks that most mobs cannot path through; these all have a penalty of -1.

The following table is a list of all pathfinding penalties and their default values. Each type of pathfinding (land, water, air) uses its own subset of these penalties. Some mobs override these default values.

Penalty type	Penalty	Description
blocked	-1	can't pathfind through block (most full solid blocks)
powder snow	-1	powder snow
fence	-1	fences walls fence gates (closed)
lava	-1	lava
unpassable rail	-1	rail
damage - other	-1	cactus sweet berry bush
closed wood door	-1	wood door
closed iron door	-1	iron door
open	0	air cave air void air
walkable	0	TNT with pressure plate on top (under the mob)
walkable door	0	a door the mob can open
trapdoor	0	trapdoors lily pad big dripleaf
danger - powder snow	0	neighboring block is powder snow
open door	0	open wood or iron door
cocoa	0	cocoa
damage - cautious	0	wither rose pointed dripstone
danger - trapdoor	0	neighboring block is trapdoor
breach water	4	there is an air block above a water block
water	8	water
water border	8	neighboring block is water
danger - fire	8	neighboring block is: fire lava magma block lit campfire lava cauldron
danger - other	8	neighboring block is: cactus sweet berry bush
honey	8	honey block
damage - fire	16	fire lava magma block lit campfire lava cauldron

Mob pathfinding penalty overrides

The following mobs override the default pathfinding penalty for some blocks:

Mob	Penalty Type	Penalty
axolotl	water	0
bee	damage - fire	-1
	water	-1
	cocoa	-1
	fence	-1
	water border	16
chicken	water	0
fox	danger - other	0
	damage - other	0
frog	trapdoor	-1
	water	4
goat	powder snow	-1
	danger - powder snow	-1
villager wandering trader	damage-fire	-1
	danger - fire	16
parrot	danger-fire	-1
	damage - fire	-1
	cocoa	-1
sniffer	water	-1
	danger - powder snow	-1
	damage - cautious	-1
strider	water	-1
	lava	0
	danger - fire	0
	damage - fire	0
turtle	close iron door	-1
	closed wood door	-1
	open door	-1
	water	0
wolf	powder snow	-1
	danger - powder snow	-1
piglin piglin brute	damage - fire	-1
	danger - fire	16
blaze	water	-1
	danger - fire	8
	damage - fire	8
	lava	8
breeze	danger - trapdoor	-1
	damage - fire	-1
drowned	water	0
enderman	water	-1
guardian	water	0
ravager	leaves	0
warden	unpassable rail	0
	damage - fire	0
	danger - fire	0
	damage - other	8
	powder snow	8
	lava	8
water creatures	water	0
wither skeleton	lava	8
zombified piglin	lava	8
animal	damage - fire	-1
	danger - fire

• All entities Move based off of random targets that are generated every tick with a priority toward their entity specific goals.
• These targets can be located anywhere in 3D space within the entity range and are only every generated when wandering or when they have no goals.
• For every target a path is generated; with the entity preferring the path with the lowest score regarding the Pathfinding penalties.
• If an entity cannot take any paths with a low enough score, or any paths without a score of -1 the entity will not move until one is found.
• If an entity's target is located inside a block (including water), the target is moved to the nearest air block above it.

This means, every entitiy when wandering will always prefer to pathfind to a block with the most blocks below it within range.

Due to the higher chance that a target will be generated within the blocks below it and moved up to the nearest air block above before generating a path.

• Pathfinding in water is roughly the same as land, however, most entities, excluding fish and drowned, will bounce on the surface preferring land due to the Pathfinding penalties of water.

• Pathfinding in air is roughly the same as land, however, there are few entities that can pathfind to air.

• Mob infighting

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