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Primematebrain

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

Overview​

This brain component governs the decision-making logic for the Prime Mate entity in Don't Starve Together. It orchestrates a behavior tree rooted around platform-aware tasks such as rowing, fixing boat leaks, engaging in combat, abandoning dead platforms, and wandering nearby. It integrates closely with components like combat, crewmember, inventory, knownlocations, timer, and walkableplatform to make context-sensitive decisions, especially when aboard a boat. The brain also includes logic to prevent undesirable interactions with specific item tags (NO_LOOTING_TAGS, NO_PICKUP_TAGS) and to prefer items with PICKUP_ONEOF_TAGS.

Usage example​

local myentity = Entity("myentity")
myentity:AddBrain("primematebrain")

The brain does not require manual configuration; it is automatically assigned and activated when the brain component is added to an entity.

Dependencies & tags​

Components used:

  • boatleak (has_leaks property)
  • boatpatch
  • combat (GetAttackRange, target property)
  • crewmember (Shouldrow, boat property)
  • health (IsDead)
  • inventory (FindItem)
  • knownlocations (GetLocation)
  • timer (TimerExists)
  • walkableplatform (platform_radius property)

Tags:

  • NO_LOOTING_TAGS and NO_PICKUP_TAGS define sets of item tags that should not be looted or picked up (e.g., "INLIMBO", "fire", "_container").
  • PICKUP_ONEOF_TAGS specifies items that satisfy pickup requirements (e.g., "_inventoryitem", "pickable", "readyforharvest").
  • NO_TAGS (local): exclusion filters used during entity searches (e.g., "FX", "DECOR", "INLIMBO").

Properties​

No public properties are explicitly initialized in the constructor. The component inherits from Brain and relies on internal state management (e.g., self.inst, self.bt).

Main functions​

PrimemateBrain:OnStart()​

  • Description: Initializes the brain’s behavior tree. This method is called automatically when the brain is started. It builds a priority-ordered behavior tree that prioritizes panic triggers, abandonment, leak repair, combat readiness, rowing, platform following, and wandering.
  • Parameters: None.
  • Returns: None.
  • Error states: None; ensures behavior tree (self.bt) is constructed and assigned.

findmaxwanderdistfn(inst)​

  • Description: Dynamically calculates the maximum wandering distance based on whether the entity is aboard a platform. If on a platform, it uses the platform’s radius minus one to avoid wandering off.
  • Parameters:
    • inst: The entity instance (Entity).
  • Returns: A numeric distance (number).
  • Error states: Falls back to MAX_WANDER_DIST (20) if the platform is unavailable or lacks a walkableplatform component.

findwanderpointfn(inst)​

  • Description: Determines the center point for wandering. If the entity is on a platform, it uses the platform’s world position; otherwise, it defaults to the "home" location from knownlocations.
  • Parameters:
    • inst: The entity instance (Entity).
  • Returns: A Vector3 position for the wander target.
  • Error states: Returns nil if the "home" location is not registered.

rowboat(inst)​

  • Description: Attempts to generate a rowing action if the entity is crewing a boat and a rowing target position can be computed. The rowing position is cached on inst.rowpos.
  • Parameters:
    • inst: The entity instance (Entity).
  • Returns: A BufferedAction if rowing is valid and a position is found; otherwise, nil.
  • Error states:
    • Returns nil if the entity lacks crewmember or Shouldrow() returns false.
    • Returns nil if FindWalkableOffset fails to find a position.
    • Position is only calculated once per call if missing.

shouldfix(inst)​

  • Description: Checks whether the entity should attempt to repair a leak. This method prepares the repair state on inst.fixboat but does not perform the action itself.
  • Parameters:
    • inst: The entity instance (Entity).
  • Returns: true if repair is applicable (item and leak found); otherwise, nil.
  • Error states:
    • Returns nil if the repair cooldown timer (patch_boat_cooldown) exists.
    • Returns nil if no repair item or leak target is found.

fixboat(inst)​

  • Description: Generates a buffered action to repair a detected leak using a boatpatch item.
  • Parameters:
    • inst: The entity instance (Entity).
  • Returns: A BufferedAction if repair is possible; otherwise, nil.
  • Error states: Same as shouldfix;此外 returns nil if the repair cooldown timer exists or the target leak/item is missing.

GetBoat(inst)​

  • Description: Returns the entity’s current platform if one exists.
  • Parameters:
    • inst: The entity instance (Entity).
  • Returns: The platform Entity or nil.
  • Error states: None.

DoAbandon(inst)​

  • Description: Attempts to generate an abandon-platform action if the platform is dead. Calculates a safe offset position on the platform’s edge.
  • Parameters:
    • inst: The entity instance (Entity).
  • Returns: A BufferedAction for ACTIONS.ABANDON with a calculated position; otherwise, nil.
  • Error states:
    • Sets inst.abandon = true only if the platform is dead.
    • Returns nil if the platform is valid but not dead or if position calculation fails.

cangettotarget(inst)​

  • Description: Determines whether the entity can reach or attack its combat target while aboard a platform. Considers range, shared platforms, and platform size.
  • Parameters:
    • inst: The entity instance (Entity).
  • Returns: true if the target is reachable; otherwise, nil.
  • Error states:
    • Returns true immediately if the entity is not on a platform and has a combat target.
    • Returns nil if the target is out of range or on a different platform.

Events & listeners​

No event listeners are registered within this brain. Event handling is delegated to behaviors (ChaseAndAttack, Wander, Follow, DoAction) and the BrainCommon utilities.