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Batbrain

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

Overview​

BatBrain implements the decision-making logic for bat entities in Don't Starve Together. It uses a Behavior Tree (BT) to manage actions such as eating, escaping from the cave, chasing targets, and interacting with team mechanics. The brain integrates with multiple components—including teamattacker, acidinfusible, eater, homeseeker, and knownlocations—to coordinate behavior based on environmental state (day/night, cave/daytime), team orders, and entity inventory.

Usage example​

local inst = CreateEntity()
inst:AddComponent("brain")
inst:AddComponent("teamattacker")
inst:AddComponent("acidinfusible")
inst:AddComponent("eater")
inst:AddComponent("homeseeker")
inst:AddComponent("knownlocations")
-- ... other setup ...
inst.components.brain:SetBrainClass("batbrain")

Dependencies & tags​

Components used: teamattacker, acidinfusible, eater, homeseeker, knownlocations, inventory, container, childspawner, hideout, inventoryitem
Tags: Checks for tags batdestination, player, _container, playerghost, fire, burnt, INLIMBO, outofreach, FX, NOCLICK, DECOR, inlimbo. Does not add or remove tags directly.

Properties​

No public properties are defined in this brain. State is encapsulated internally within the Behavior Tree and via external component state.

Main functions​

BatBrain:OnStart()​

  • Description: Initializes and constructs the Behavior Tree root node, incorporating panic responses, day/night navigation, team formation logic, and acid-infusion behavior.
  • Parameters: None.
  • Returns: Nothing.
  • Error states: None; assumes required components exist. Behavior may not function correctly if key components (teamattacker, eater, homeseeker, acidinfusible, knownlocations) are missing.

BatBrain:OnInitializationComplete()​

  • Description: Records the entity’s current position as the "home" location in knownlocations, preventing overwriting if already set.
  • Parameters: None.
  • Returns: Nothing.

GoHomeAction(inst)​

  • Description: Returns an ACTION.GOHOME action targeting the bat’s home if valid and not in a team.
  • Parameters: inst (Entity) — the bat entity.
  • Returns: BufferedAction or nil.
  • Error states: Returns nil if homeseeker or home is invalid, or if the entity is in a team.

EscapeAction(inst)​

  • Description: Returns an action to escape to a sinkhole (batdestination) at night, or to GOHOME if in cave day.
  • Parameters: inst (Entity) — the bat entity.
  • Returns: BufferedAction or nil.
  • Error states: Returns nil if no valid batdestination is found or the destination lacks childspawner/hideout.

EatFoodAction(inst)​

  • Description: Prioritizes eating food from inventory; if none available, attempts to pick up edible items within range (SEE_FOOD_DIST = 30).
  • Parameters: inst (Entity) — the bat entity.
  • Returns: BufferedAction or nil.
  • Error states: Returns nil if inventory or eater component is missing or no edible food found. Skips if state has busy tag.

StealNitreAction(inst)​

  • Description: Scans nearby entities and containers for "nitre" items to steal. Prioritizes equipped inventory (e.g., backpack) over direct slots.
  • Parameters: inst (Entity) — the bat entity.
  • Returns: BufferedAction with ACTIONS.STEAL or nil.
  • Error states: Returns nil if no nitre found or if inventoryitem.owner is nil for target item.

AcidBatAction(inst)​

  • Description: Selects an action (EatFood, StealNitre, or fallback) based on teamattacker orders. Always leaves formation if an action is chosen.
  • Parameters: inst (Entity) — the bat entity.
  • Returns: BufferedAction or nil.
  • Error states: Returns nil if no valid action found or components (teamattacker, eater, inventory) missing.

LeaveFormation(inst)​

  • Description: Instructs teamattacker to ignore formation restrictions.
  • Parameters: inst (Entity) — the bat entity.
  • Returns: Nothing.

LeaveTeam(inst)​

  • Description: Instructs teamattacker to leave the team; notifies leader if present.
  • Parameters: inst (Entity) — the bat entity.
  • Returns: Nothing.

Events & listeners​

  • Listens to: "panic" (via EventNode) — triggers panic behavior and forces formation/team exit.
  • Pushes: None directly. Delegates to action system and Behavior Tree for event propagation.