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Birdbrain

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

Overview​

BirdBrain is a behavior tree–based AI brain component that governs how bird-like entities respond to threats. It primarily determines when the entity should initiate a "fly away" action, such as fleeing from nightfall, lunar hail, fire damage, or the presence of nearby threats (e.g., players, monsters). It relies on the hauntable, health, and burnable components to detect specific danger states.

The brain is used by prefabs like bird, parrot, and similar flyers, ensuring they flee automatically when appropriate conditions are met.

Usage example​

local inst = CreateEntity()
inst:AddComponent("birdbrain")
-- No further manual setup required; the brain automatically activates on stategraph start
-- via OnStart() when the entity enters a flight-capable state.

Dependencies & tags​

Components used: hauntable, health, burnable, stategraph
Tags: Uses SHOULDFLYAWAY_MUST_TAGS = { "notarget", "INLIMBO" } and SHOULDFLYAWAY_CANT_TAGS = { "player", "monster", "scarytoprey" } internally for FindEntity filtering.

Properties​

No public properties.

Main functions​

OnStart()​

  • Description: Initializes the behavior tree for the bird entity. Constructs a priority-based node tree that evaluates panic (from hauntable), flight conditions (via ShouldFlyAway), and named events (threatnear, gohome) to trigger the fly_away callback.
  • Parameters: None.
  • Returns: Nothing.
  • Notes: Stores the resulting behavior tree in self.bt. The function captures self.inst via closure in fly_away_fn, ensuring the correct entity is acted upon.

Events & listeners​

  • Listens to: threatnear, gohome, and internal behavior tree events (handled via EventNode).
  • Pushes: flyaway (via FlyAway) whenever the entity decides to flee.