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Spatbrain

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

Overview​

spatbrain implements the behavior tree for the Spat entity, a boss creature in Don't Starve Together. It manages high-priority threat responses such as panic triggers, weapon-specific attacks (melee and phlegm/projectile), fleeing when targeted by enemies, orientation toward nearby players, and routine wandering. The brain integrates with the Brain base class and leverages external behavior modules (ChaseAndAttack, RunAway, FaceEntity, Wander) and combat-related components (combat, inventory, equippable, pinnable) to orchestrate complex AI behavior dynamically.

Usage example​

This component is typically attached to an entity (e.g., inst) during its initialization. No direct manual calling of public methods is required—the brain activates automatically when inst.components.brain:Start() is invoked.

inst:AddComponent("brain")
inst.brain = Spatbrain(inst)
-- The behavior tree is constructed in Spatbrain:OnStart(), triggered by Brain component's Start() call.

Dependencies & tags​

Components used:

  • combat (used for target, InCooldown(), ResetCooldown())
  • inventory (used for Equip() calls)
  • equippable (used for IsEquipped() checks on weapons)
  • pinnable (used for IsValidPinTarget() checks on combat targets)

Tags: None identified as directly added/removed by spatbrain itself. The behavior tree uses tag-based filtering (HUNTER_PARAMS) for target selection in RunAway.

Properties​

No public properties are declared in the constructor or method definitions. The class inherits from Brain and holds only self.bt (the behavior tree instance), which is assigned in OnStart(). All relevant state is encapsulated via functions and constants.

Main functions​

Spatbrain:OnStart()​

  • Description: Initializes and constructs the behavior tree root node for the Spat. This function is called when the entity's brain component starts. It creates a priority-based behavior tree with nodes for panic handling, melee/phlegm attack conditions, fleeing, face-targeting, and wandering.
  • Parameters: None.
  • Returns: None.
  • Error states: If BrainCommon.PanicTrigger, RunAway, FaceEntity, Wander, or ChaseAndAttack are undefined or misconfigured, the behavior tree will fail to construct at runtime. No validation is performed at startup.

CanMeleeNow(inst)​

  • Description: Determines whether the Spat should execute a melee attack. Returns true only if a valid target exists, the combat cooldown has expired, and the target is either not pinning-eligible or is a valid pin target (and thus should not be melee'd—see note), and the Spat is within FORCE_MELEE_DIST of the target.
  • Parameters:
    • inst: The Spat entity instance.
  • Returns: true if melee is appropriate, otherwise false.
  • Error states: Returns false if inst.components.combat.target is nil, or if the combat cooldown is active, or if the pinnable component exists on the target but IsValidPinTarget() returns true.

EquipMeleeAndResetCooldown(inst)​

  • Description: Equips the melee weapon (inst.weaponitems.meleeweapon) and resets the combat cooldown. Used when preparing to attack a target the Spat is stuck on or needs immediate melee engagement.
  • Parameters:
    • inst: The Spat entity instance.
  • Returns: None.
  • Error states: Does nothing if the melee weapon is already equipped.

EquipMelee(inst)​

  • Description: Equips the melee weapon without resetting cooldown. Used for general melee preparation when cooldown management is not required.
  • Parameters:
    • inst: The Spat entity instance.
  • Returns: None.
  • Error states: Does nothing if the melee weapon is already equipped.

CanPhlegmNow(inst)​

  • Description: Determines whether the Spat should shoot phlegm (projectile). Returns true only if a target exists, the target has the pinnable component and is a valid pin target, and the combat cooldown has expired.
  • Parameters:
    • inst: The Spat entity instance.
  • Returns: true if phlegm attack is appropriate, otherwise false.
  • Error states: Returns false if inst.components.combat.target is nil, the target lacks pinnable, IsValidPinTarget() returns false, or the combat cooldown is active.

EquipPhlegm(inst)​

  • Description: Equips the phlegm weapon (inst.weaponitems.snotbomb). Used to switch to the projectile weapon before launching phlegm.
  • Parameters:
    • inst: The Spat entity instance.
  • Returns: None.
  • Error states: Does nothing if the phlegm weapon is already equipped.

Events & listeners​

None identified. The brain does not register or fire any events directly. It reacts to runtime conditions evaluated in node guards (e.g., CanMeleeNow, CanPhlegmNow) and uses the behavior tree execution loop for flow control.