Buzzardbrain

Based on game build 714014 | Last updated: 2026-03-03

Overview

Buzzardbrain implements the behavior tree for buzzard entities in DST. Its primary responsibility is to guide buzzard movement and interaction: seeking and consuming placed food (e.g., corpses), defending food when attacked, and fleeing threats or fire depending on mutation state. Regular buzzards (non-mutated) prioritize food they can see and aggressively defend it; mutated buzzards (tagged lunar_aligned) do not consume food but instead actively seek corpses to defend and attack non-mutated intruders. The brain integrates with the combat, health, burnable, and locomotor components, and uses custom behavior nodes (StandAndAttack, Wander, Leash) to drive state transitions.

Usage example

local inst = CreateEntity()
inst:AddComponent("brain")
inst.components.brain:SetBrainClass("buzzardbrain")
-- Additional setup (tags, combat, health, etc.) handled by prefab definition

Dependencies & tags

Components used: combat, health, burnable, locomotor
Tags checked: buzzard, lunar_aligned, player, monster, scarytoprey, notarget, playerghost, creaturecorpse, NOCLICK, NOINTERACT, INLIMBO, outofreach, edible_omni, edible_meat, edible_veggie, edible_insect, edible_fruit, edible_mushroom
Tags added: None

Properties

Property	Type	Default Value	Description
corpse	entity or nil	nil	Reference to the current corpse being eaten/defended.
corpse_time	number	GetTime()	Timestamp of last corpse abandonment; used for mutation-based flight logic.
threat	boolean or entity	false	Cached threat: false = untested, nil = none found, entity = threat found.
shouldGoAway	boolean	false	Flag indicating the buzzard should flee.
_on_corpse_ignite	function	nil	Event handler attached to the corpse's onignite.
_on_corpse_chomped	function	nil	Event handler attached to the corpse's chomped.

Main functions

OwnCorpse(corpse)

• Description: Claims a corpse for consumption or defense. Registers event listeners for onignite and chomped events on the corpse. Ensures only a limited number of buzzards (based on corpse size) can claim the same corpse.
• Parameters: corpse (entity) — The corpse entity to claim.
• Returns: Nothing.
• Error states: Does nothing if the corpse is already fully occupied by the configured max owners.

LoseCorpseOwnership()

• Description: Releases ownership of the current corpse, removes event listeners, and resets internal state. Updates corpse_time.
• Parameters: None.
• Returns: Nothing.

ShouldIgnoreCorpse(corpse)

• Description: Determines if this buzzard should be prevented from eating the given corpse due to max-occupancy limits.
• Parameters: corpse (entity) — The corpse entity to check.
• Returns: true if this buzzard should ignore the corpse; false otherwise.
• Error states: None. Uses global ignorethese table and SIZE_TO_NUM_OWNERS mapping.

FindCorpse()

• Description: Searches for a valid corpse within range. If found, calls OwnCorpse; otherwise, calls LoseCorpseOwnership.
• Parameters: None.
• Returns: true if a corpse was found and claimed; false otherwise.
• Error states: None. Validity includes burning checks for non-mutated buzzards.

IsCorpseValid()

• Description: Checks if the currently owned corpse (self.corpse) is still valid for consumption/defense.
• Parameters: None.
• Returns: true if the corpse is valid; false otherwise.
• Error states: Returns false if self.corpse is nil or invalid.

GetCorpsePosition()

• Description: Returns the position of the current valid corpse, or nil if none.
• Parameters: None.
• Returns: {x, y, z} (position vector) or nil.

FindThreat()

• Description: Finds a nearby threat within SEE_THREAT_DIST (shorter for mutated buzzards). Uses caching via the threat property to avoid recomputation.
• Parameters: None.
• Returns: Entity (threat) or nil.
• Error states: None.

IsThreatened()

• Description: Determines if the buzzard is currently threatened (i.e., a threat exists and the stategraph is not busy).
• Parameters: None.
• Returns: Entity (threat) or nil.
• Error states: Returns nil if the buzzard is in a busy state (sleeping, busy, flight).

DealWithThreat()

• Description: Handles threat response: if near food/corpse, attempts to defend (via combat:SetTarget or combat:SuggestTarget); if threat is unreachable or no food present, sets shouldGoAway to flee.
• Parameters: None.
• Returns: true if the buzzard engaged the threat or is defending; false if it failed to engage (e.g., threat already targeted by another buzzard in mutated case).
• Error states: Returns false only for mutated buzzards if combat:SuggestTarget fails.

DoUpdate()

• Description: Called during behavior tree updates to refresh internal caches.
• Parameters: None.
• Returns: Nothing.

OnStart()

• Description: Initializes the behavior tree root node with priority-based conditional logic: fleeing fire/threats, defending food, eating, wandering, and leashing to corpse. Sets up mutated vs non-mutated branching.
• Parameters: None.
• Returns: Nothing.
• Error states: None. Behavior tree built using PriorityNode, WhileNode, IfNode, and action nodes (StandAndAttack, Wander, Leash, FaceEntity, DoAction, ActionNode).

OnStop()

• Description: Releases corpse ownership and cleans up event listeners.
• Parameters: None.
• Returns: Nothing.

Events & listeners

• Listens to:
  • onignite on the current corpse: Suggests the igniting entity as a combat target if valid.
  • chomped on the current corpse: Sets the chomping entity as a combat target if valid (aggressive against non-mutated buzzards for regular buzzards; against non-mutated entities for mutated buzzards).
• Pushes:
  • corpse_eat — emitted immediately when the buzzard faces and begins eating a valid corpse (during chomp node execution).
  • locomote — emitted by locomotor:Stop() (via OnStop, DealWithThreat, EatFoodAction, etc.).