Pigguardbrain

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

Overview

This component defines the AI behavior tree for pig guard NPCs in Don't Starve Together. It coordinates high-level actions—such as combat, fleeing, homing to their designated torch, seeking food, and patrolling—through a priority-based behavior tree rooted in PriorityNode. It relies heavily on external components for state and utility (combat, inventory, eater, homeseeker, knownlocations) and integrates with common brain utilities (BrainCommon) and movement/action behaviors (ChaseAndAttack, RunAway, Wander, FaceEntity). The behavior tree executes in a loop, re-evaluating nodes every frame to ensure responsive adaptation to changing conditions.

Usage example

-- Attaching the PigGuardBrain to an entity (e.g., in a prefab definition)
inst:AddComponent("brain")
inst.components.brain:SetBrainClass("brains/pigguardbrain")

Dependencies & tags

Components used:

• combat: to check for targets, cooldowns, and combat state
• inventory: to locate food items and torch fuel
• eater: to determine edible items
• homeseeker: to identify and verify the home torch location
• knownlocations: to retrieve the "home" location

Tags:

• This component does not directly add or remove tags on the entity.

Properties

Property	Type	Default Value	Description
bt	BT (Behavior Tree)	nil	Initialized in OnStart; the active behavior tree instance for decision-making.

Note: The PigGuardBrain class inherits from Brain, and its primary state (self.bt) is set up in OnStart. No additional public properties are declared in the constructor.

Main functions

GoHomeAction(inst)

• Description: Returns an action to walk to the pig guard's home location (typically the torch) if no combat target is present and the guard is too far away. Used by the behavior tree to trigger movement to the torch when necessary.
• Parameters:
  • inst: Entity instance—the pig guard NPC.
• Returns: BufferedAction if a home location exists and distance exceeds GO_HOME_DIST; otherwise nil.
• Error states: Returns nil if inst.components.combat.target is set or if "home" location is not registered.

AddFuelAction(inst)

• Description: Attempts to refuel the pig guard's home torch if it is low (section <= 1). First searches inventory for "pigtorch_fuel"; if none exists, spawns and gives one. Returns an action to add fuel to the torch.
• Parameters:
  • inst: Entity instance—the pig guard NPC.
• Returns: BufferedAction to add fuel to the torch if fuel is available; otherwise nil.
• Error states: Returns nil if home is nil, fuel is unavailable, or the torch section is above 1.

FindFoodAction(inst)

• Description: Searches the pig guard's inventory for an item it can eat (via eater:CanEat) and returns an EAT action to consume it.
• Parameters:
  • inst: Entity instance—the pig guard NPC.
• Returns: BufferedAction to eat edible food if found; otherwise nil.
• Error states: Returns nil if inventory or eater component is missing, or no edible item is found.

GetFaceTargetFn(inst)

• Description: Finds the closest nearby player (within START_FACE_DIST) eligible for the guard to face. Skips targets tagged "notarget".
• Parameters:
  • inst: Entity instance—the pig guard NPC.
• Returns: Target Entity if found and not notarget; otherwise nil.

KeepFaceTargetFn(inst, target)

• Description: Determines whether the guard should continue facing a target (used during face behavior maintenance). Returns true if the target remains within KEEP_FACE_DIST and is not "notarget".
• Parameters:
  • inst: Entity instance—the pig guard NPC.
  • target: Entity—the entity being faced.
• Returns: boolean indicating whether to keep facing the target.

ShouldGoHome(inst)

• Description: Checks whether the guard should return to its home location because it is too far away (GO_HOME_DIST).
• Parameters:
  • inst: Entity instance—the pig guard NPC.
• Returns: boolean; true if "home" location exists and squared distance to it exceeds GO_HOME_DIST * GO_HOME_DIST.

GetRunAwayTarget(inst)

• Description: Returns the current combat target as the source of danger to flee from.
• Parameters:
  • inst: Entity instance—the pig guard NPC.
• Returns: Entity—the combat target (often a player or enemy attacking the guard).

OnStart()

• Description: Constructs and initializes the behavior tree's root node with a priority-ordered list of behaviors, including panic responses, combat logic (chase/attack, dodge), homing, eating, fueling, facing targets, and wandering.
• Parameters: None.
• Returns: None.
• Implementation details: The behavior tree is built using PriorityNode with sub-nodes like ChattyNode, WhileNode, ChaseAndAttack, RunAway, DoAction, FaceEntity, and Wander. All action selectors are wrapped in WhileNode or conditional guards (ChattyNode) to respond dynamically to state changes.

Events & listeners

This component does not register any event listeners or push custom events. It relies entirely on the behavior tree's node evaluation loop and component state queries for updates.