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Slurtlebrain

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

Overview​

SlurtleBrain is a brain component that defines the AI behavior for slurtle and snurtle entities. It uses a behavior tree (BT) with prioritized nodes to coordinate complex actions such as seeking shelter, avoiding damage (including via a shield mechanic), stealing food from other entities, consuming food, and navigating back to a home location when hungry. The brain integrates with several components—homeseeker, eater, inventory, burnable, container, pickable, and knownlocations—to make context-aware decisions. It is designed to interact dynamically with the game world, prioritize self-preservation, and exploit available food sources.

Usage example​

Typically, this brain component is assigned to a slurtle or snurtle entity instance during its prefab definition. The component itself is instantiated by the game's AI system and does not require manual intervention. However, for demonstration, here is how the brain might be added and activated on an entity:

local SlurtleBrain = require("brains/slurtlebrain")
inst:AddBrain(SlurtleBrain(inst))

Once added, the brain automatically manages state transitions and behavior selection via its internal behavior tree.

Dependencies & tags​

Components used: homeseeker, burnable, inventory, eater, edible, container, pickable, knownlocations, inventoryitem, bufferedaction.

Tags: This component does not directly add or remove entity tags; it checks existing tags via HasTag, HasDebuff, and IsOnValidGround to make decisions.

Properties​

No public properties are defined in the constructor; this brain relies entirely on behaviors and external component states.

Main functions​

This brain defines only one primary method, OnStart, which initializes the behavior tree.

SlurtleBrain:OnStart()​

  • Description: Constructs and assigns the behavior tree root node by evaluating prioritized behaviors: using shield when damaged, panicking at hazards (e.g., electric fences), chasing and attacking targets, eating or stealing food, returning home if hungry, and wandering near home otherwise.
  • Parameters: None.
  • Returns: nil.
  • Error states: None documented; fails silently if referenced components (e.g., homeseeker, inventory) are missing.

Supporting action functions (not methods)​

The following functions are defined locally within the file and passed to DoAction nodes:

GoHomeAction(inst)​

  • Description: Returns a buffered action for the entity to go to its assigned home if the home is valid and not burning.
  • Parameters: inst — the entity instance.
  • Returns: BufferedAction or nil if conditions are not met.
  • Error states: Returns nil if homeseeker or its home is invalid, or if the home is burning.

ShouldGoHome(inst)​

  • Description: Determines whether the entity is sufficiently hungry to return home.
  • Parameters: inst — the entity instance.
  • Returns: boolean — true if the time since last meal exceeds HUNGER_TOLERANCE (70 seconds).
  • Error states: None.

IsFoodValid(item, inst)​

  • Description: Validates that a potential food item is safe and edible.
  • Parameters:
    • item — the food entity to check.
    • inst — the slurtle instance.
  • Returns: boolean — true if the item has been alive for at least 8 seconds, is on valid ground, and is edible by the slurtle.
  • Error states: None.

EatFoodAction(inst)​

  • Description: Attempts to eat food from inventory or pick up nearby food if hungry and not busy.
  • Parameters: inst — the entity instance.
  • Returns: BufferedAction or nil.
  • Error states: Returns nil if the entity is busy (HasStateTag("busy")), has no inventory or eater component, or no valid food is found.

StealFoodAction(inst)​

  • Description: Scans nearby entities for food in their inventories, containers, or as slurtlepickable items, and attempts to steal one via a buffered steal action.
  • Parameters: inst — the entity instance.
  • Returns: BufferedAction or nil.
  • Error states: Returns nil if the entity is busy, no nearby valid targets exist, or no edible items are found in target inventories/containers/pickables. Also skips items belonging to entities with healingsalve_acidbuff or owned by other slurtles.

Events & listeners​

This brain does not register or push any events directly. All behavioral decisions are driven by the behavior tree evaluation cycle and component state queries.