Shadow Rookbrain

Based on game build 714014 | Last updated: 2026-02-27

Overview

This component defines the artificial intelligence (Brain) for Shadow Rook entities in Don't Starve Together. It implements behavior tree logic to coordinate movement, combat, facing orientation, and timed despawn behavior. The brain integrates with the Combat and Health components to maintain accurate targeting and respond to entity states, and uses the Wander, FaceEntity, and ChaseAndAttack behaviors to orchestrate movement and orientation behavior. It ensures the Rook maintains a defensive posture—prioritizing facing its target while optionally chasing if the target is outside attack range or out of combat cooldown.

Usage example

The brain is attached to an entity instance during prefab initialization, typically as part of a boss entity (e.g., shadow_rook.lua). Once added via inst:AddComponent("brain") (with Shadow_RookBrain as the registered brain type), the behavior tree is automatically initialized on OnStart().

inst:AddComponent("brain")
inst.components.brain:SetBrainClass("shadow_rookbrain")
inst:StartBrain()

Dependencies & tags

Components used:

• inst.components.combat — for target checking (HasTarget), cooldown state (InCooldown), and attack range.
• inst.components.health — to verify target is alive via IsDead.

Tags checked:

• "notarget" — used to skip invalid targets (e.g., non-solid or invulnerable entities).
• "playerghost" — excluded as valid facing/chase targets.
• "idle" — state tag used internally to trigger taunt animations.

Tags added: None identified.

Properties

Property	Type	Default Value	Description
_shouldchase	boolean	false	Internal cache indicating whether the entity should currently be in chase mode. Used to prevent rapid toggling due to fluctuating distance conditions.

Main functions

OnStart()

• Description: Initializes the behavior tree for the Shadow Rook, setting up prioritized tasks that govern chasing, facing, idle taunting, and despawn behavior.
• Parameters: None.
• Returns: None.
• Error states: None—assumes valid Combat and Health components are attached.

GetFaceTargetFn(inst) (local)

• Description: Computes the preferred entity to face. Prioritizes the current combat target, otherwise falls back to the nearest player within START_FACE_DIST (8 units). Excludes entities with "notarget" tag.
• Parameters:
  • inst: The entity instance whose brain is requesting the target.
• Returns: Entity or nil.
• Error states: Returns nil if no target exists or the only candidates are excluded by tag or distance.

KeepFaceTargetFn(inst, target) (local)

• Description: Determines whether to continue facing a given target, ensuring it remains alive, valid, and within proximity.
• Parameters:
  • inst: The entity instance.
  • target: The proposed target entity to keep facing.
• Returns: boolean — true if target is valid and within KEEP_FACE_DIST (15 units), false otherwise.
• Error states: Returns false if target lacks Health component, is dead, is a player ghost, has "notarget", or is too far.

ShouldChase(self) (local)

• Description: Evaluates whether the entity should enter chase mode. Updates the internal _shouldchase cache and returns the decision.
• Parameters:
  • self: The brain instance.
• Returns: boolean — true if either no target exists, combat is not in cooldown, or the target is outside adjusted attack range (attackrange ± 2 depending on previous chase state).
• Error states: None—uses hysteresis (±2) to reduce oscillation near the attack range boundary.

Events & listeners

• Pushes:

  • "despawn" — Fired via self.inst:PushEvent("despawn") after a delay (TUNING.SHADOW_CHESSPIECE_DESPAWN_TIME), triggered by the despawn subtree in the behavior tree.

• Listens to: None—this brain component does not directly register event listeners.

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