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Moosebrain

Based on game build 722832 | Last updated: 2026-04-22

Overview​

MooseBrain is a behavior tree brain that controls the AI for the Moose entity. It manages priority-based behaviors including combat engagement, egg-laying mechanics, territorial leashing, and player-facing interactions. The brain uses a PriorityNode structure where higher-priority behaviors interrupt lower ones.

Usage example​

local inst = SpawnPrefab("moose")
local brain = require("brains/moosebrain")
RunBrain(inst, brain)

-- Brain automatically handles:
-- - Combat via ChaseAndAttack
-- - Egg laying when WantsToLayEgg is true
-- - Leashing to landpoint location
-- - Facing nearby players

Dependencies & tags​

External dependencies:

  • behaviours/faceentity -- provides FaceEntity behavior node for player-facing
  • behaviours/chaseandattack -- provides ChaseAndAttack behavior node for combat
  • behaviours/leash -- provides Leash behavior node for territorial bounds

Components used:

  • combat -- checks target property to determine if engaged in combat
  • entitytracker -- calls GetEntity("egg") to check for existing egg entity
  • knownlocations -- calls GetLocation("landpoint") for leash bounds and RememberLocation("spawnpoint") for spawn tracking

Tags:

  • notarget -- checked on target entities to exclude from facing behavior
  • busy -- state tag checked to prevent facing during busy animations

Properties​

PropertyTypeDefault ValueDescription
btBehaviorTreenilReference to the behavior tree instance created in OnStart().

Main functions​

OnStart()​

  • Description: Initializes the behavior tree with priority-ordered behavior nodes. Sets up combat, egg-laying, leashing, facing, and wandering behaviors. Higher priority nodes interrupt lower ones.
  • Parameters: None
  • Returns: None
  • Error states: Errors if self.inst is nil when accessing components or calling behavior functions. Errors if knownlocations component is missing when calling GetLocation().

OnInitializationComplete()​

  • Description: Records the entity's spawn position to the knownlocations component under the "spawnpoint" key. Called when brain initialization finishes.
  • Parameters: None
  • Returns: None
  • Error states: Errors if self.inst is nil or if knownlocations component is not present on the entity.

GoHome(inst) (local)​

  • Description: Returns a BufferedAction for the GOHOME action if the entity should go away and has no combat target. Used by the WhileNode in the behavior tree.
  • Parameters: inst -- the entity instance
  • Returns: BufferedAction instance or nil if conditions not met
  • Error states: None

GetFaceTargetFn(inst) (local)​

  • Description: Finds the closest player within START_FACE_DIST that does not have the "notarget" tag and when the entity is not in a busy state. Used by FaceEntity behavior.
  • Parameters: inst -- the entity instance
  • Returns: Player entity instance or nil if no valid target found
  • Error states: None

KeepFaceTargetFn(inst, target) (local)​

  • Description: Validates whether the entity should continue facing a target. Returns false if entity is busy, has notarget tag, or is beyond KEEP_FACE_DIST from target.
  • Parameters:
    • inst -- the entity instance
    • target -- the target entity being faced
  • Returns: boolean -- true if should keep facing, false otherwise
  • Error states: None

LayEgg(inst) (local)​

  • Description: Returns a BufferedAction for the LAYEGG action if the entity wants to lay an egg and no egg entity is currently tracked. Used by DoAction in the behavior tree.
  • Parameters: inst -- the entity instance
  • Returns: BufferedAction instance or nil if conditions not met
  • Error states: None

Events & listeners​

  • Listens to: None identified
  • Pushes: None identified