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Carratbrain

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

Overview​

CarratBrain is a brain component responsible for controlling the behavior of the Carrat entity in Don't Starve Together. It implements a behavior tree (BT) with conditional execution flows based on the Carrat's racing state (yotc_racecompetitor.racestate) and other environmental factors (e.g., fire, enemies, food availability). It coordinates with components such as health, burnable, eater, hauntable, and yotc_racecompetitor/yotc_racestats to respond dynamically to in-game conditions. The brain integrates standard behaviors (Wander, RunAway, Panic, FaceEntity, Leash) and defines custom action triggers (e.g., eat_food_action, returntobeefalo).

Dependencies & Tags​

  • Components used:
    • health (self.inst.components.health)
    • burnable (self.inst.components.burnable)
    • eater (self.inst.components.eater)
    • entitytracker (self.inst.components.entitytracker)
    • hauntable (self.inst.components.hauntable)
    • inventoryitem (self.inst.components.inventoryitem)
    • yotc_racecompetitor (self.inst.components.yotc_racecompetitor)
    • yotc_racestats (self.inst.components.yotc_racestats)
  • Tags checked/avoided:
    • INLIMBO, outofreach, scarytoprey, character, beefalo, baby, HasCarrat, planted, Held
  • Behaviors imported:
    • doaction, faceentity, leash, panic, runaway, wander
    • behaviors/doaction, behaviors/faceentity, behaviors/leash, behaviors/panic, behaviors/runaway, behaviors/wander
  • Constants:
    • AVOID_PLAYER_DIST, AVOID_PLAYER_DIST_SQ, AVOID_PLAYER_STOP
    • SEE_BAIT_DIST, MAX_WANDER_DIST
    • RACE_WANDER_DURATION, RACE_WANDER_MAX_DIST, RACE_WANDER_TIMES, RACE_WANDER_DATA

Properties​

No public instance properties are explicitly declared in the constructor or elsewhere. Behavior state is managed internally via the self.bt behavior tree and helper functions.

Main Functions​

CarratBrain:OnStart()​

  • Description: Initializes the behavior tree for the Carrat. Constructs a priority-based root node that handles states such as OnFire, AvoidElectricFence, racing (with sub-states prerace, postrace, raceover, racing, panic_race_start), panic from haunting, fleeing from scary entities, eating food, returning to beefalo, and wandering. The tree is assigned to self.bt.
  • Parameters: None.
  • Returns: None. Assigns the root behavior tree to self.bt.

Helper Functions (Internal)​

racing_get_checkpoint(inst)​

  • Description: Returns the next race checkpoint entity if the entity is a race competitor; otherwise nil.
  • Parameters:
    • inst (EntityInstance): The Carrat entity instance.
  • Returns: EntityInstance? — The next checkpoint entity or nil.

racing_get_checkpoint_pt(inst)​

  • Description: Returns the world position (Vector3) of the next race checkpoint, or nil. Triggers the "carrat_error_walking" event if the Carrat has speed 0 and has not yet spoken about walking issues (tracked via walkspeechdone).
  • Parameters:
    • inst (EntityInstance): The Carrat entity instance.
  • Returns: Vector3? — The checkpoint position or nil.

get_race_direction(inst)​

  • Description: Computes a perturbed heading toward the next race checkpoint, incorporating directional variance based on the Carrat's yotc_racestats.direction_modifier.
  • Parameters:
    • inst (EntityInstance): The Carrat entity instance.
  • Returns: number? — The calculated heading in radians, or nil if no checkpoint exists.

is_racecompetitor(inst)​

  • Description: Checks whether the entity has the yotc_racecompetitor component.
  • Parameters:
    • inst (EntityInstance): The Carrat entity instance.
  • Returns: boolean.

is_waiting_for_race_to_start(inst)​

  • Description: Checks if the Carrat is in the "prerace" state.
  • Parameters:
    • inst (EntityInstance): The Carrat entity instance.
  • Returns: boolean.

get_trainer(inst)​

  • Description: Retrieves the trainer entity (via entitytracker key "yotc_trainer"), if present.
  • Parameters:
    • inst (EntityInstance): The Carrat entity instance.
  • Returns: EntityInstance? — The trainer entity or nil.

get_nearby_trainer_pt(inst)​

  • Description: Returns the trainer's position if within TUNING.YOTC_RACER_TRAINER_DIST; otherwise nil.
  • Parameters:
    • inst (EntityInstance): The Carrat entity instance.
  • Returns: Vector3? — The trainer's position or nil.

edible(inst, item)​

  • Description: Determines if item is edible for the Carrat based on multiple conditions (e.g., CanEat, is bait, not held, not planted, on passable terrain, same platform).
  • Parameters:
    • inst (EntityInstance): The Carrat entity instance.
    • item (EntityInstance): The potential food item.
  • Returns: boolean.

eat_food_action(inst)​

  • Description: Searches for edible bait items within SEE_BAIT_DIST, avoiding items too close to scarytoprey entities (respects AVOID_PLAYER_DIST). Returns a buffered EAT action for the nearest safe food, or nil if no valid target is found.
  • Parameters:
    • inst (EntityInstance): The Carrat entity instance.
  • Returns: BufferedAction? — An action targeting an edible item or nil.

returntobeefalo(inst)​

  • Description: If inst.beefalo_carrat is true, searches for a nearby beefalo (excluding babies and those already carrying a Carrat), and returns a GOHOME buffered action.
  • Parameters:
    • inst (EntityInstance): The Carrat entity instance.
  • Returns: BufferedAction? — A GOHOME action targeting a beefalo or nil.

Events & Listeners​

  • Pushes:
    • "carrat_error_walking" — Triggered inside racing_get_checkpoint_pt when the Carrat has speed 0 and has not yet marked walkspeechdone as true. Used for speech or UI feedback in race contexts.