Fruitflybrain

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

Overview

FruitFlyBrain is a brain component responsible for defining the AI behavior of fruit fly entities in Don't Starve Together. It uses a behavior tree (BT) to orchestrate high-level decision-making, including wandering, attacking plants, sowing weeds on soil tiles, returning home, and optionally summoning minions (for lord fruit flies). The brain integrates with components such as combat, follower, leader, and knownlocations to coordinate movement and targeting logic. It inherits from the base Brain class and customizes behavior based on whether the entity has the lordfruitfly tag.

Dependencies & Tags

• Components used:

  • combat — to check for active targets and attack cooldowns
  • follower — to retrieve leader position for home navigation
  • leader — to determine if this entity is a leader and to prevent duplicate targeting
  • knownlocations — to retrieve the "home" location when no leader exists

• Tags:

  • lordfruitfly — determines extended behavior: enables child summoning, dodge, and attack staging logic.

Properties

Property	Type	Default Value	Description
self.inst	Entity	—	The entity instance this brain controls.
self.bt	BT	nil	Behavior tree instance, initialized in OnStart.
inst.soiltarget	Entity or nil	nil	Cached soil target for sowing weeds; set by ShouldSowWeeds.
inst.planttarget	Entity or nil	nil	Target plant for attack/farm actions (set externally by FindFarmPlant).

Main Functions

CanSpawnChild(inst)

• Description: Determines whether the fruit fly is allowed to spawn a child. Requires sufficient age, remaining spawn quota, and an active combat target or pending plant/soil target.
• Parameters:
  • inst (Entity): The fruit fly entity instance.
• Returns: boolean — true if all conditions are met for spawning a child.

GetFollowPos(inst)

• Description: Computes the position the fruit fly should use for navigation and home return logic. Prioritizes the leader's position (via follower), falls back to the "home" location (via knownlocations), or defaults to the entity's own position.
• Parameters:
  • inst (Entity): The fruit fly entity instance.
• Returns: Vector — The target position for follow/home behavior.

GetLeader(inst)

• Description: Determines the effective leader of this fruit fly. If the entity itself has a leader component, it is considered the leader; otherwise, it returns the leader of its follower component.
• Parameters:
  • inst (Entity): The fruit fly entity instance.
• Returns: Entity or nil — The leader entity, if any.

GoHomeAction(inst)

• Description: Constructs a WALKTO action that moves the entity to its home position (via GetFollowPos) if no combat target is present.
• Parameters:
  • inst (Entity): The fruit fly entity instance.
• Returns: Action or nil — A buffered walk action, or nil if there is a combat target.

ShouldGoHome(inst)

• Description: Checks whether the entity is farther away from its home position than GO_HOME_DIST (30 world units). Uses squared distance to avoid sqrt.
• Parameters:
  • inst (Entity): The fruit fly entity instance.
• Returns: boolean — true if distance exceeds threshold.

IsNearFollowPos(inst, soil)

• Description: Checks whether a given soil entity is within SEE_DIST (20 world units) of the entity's home/follow position.
• Parameters:
  • inst (Entity): The fruit fly entity instance.
  • soil (Entity): The soil entity to check.
• Returns: boolean — true if the soil is near the follow position.

SowWeedsAction(inst)

• Description: Constructs a PLANTWEED action on the cached soiltarget if set.
• Parameters:
  • inst (Entity): The fruit fly entity instance.
• Returns: Action or nil — A buffered plant weeds action, or nil if no soil target.

ShouldSowWeeds(inst)

• Description: Searches for a suitable soil tile within SEE_DIST using FindEntity, ensuring the tile is near the home/follow position and not already targeted by another entity (via leader:IsTargetedByOther).
• Parameters:
  • inst (Entity): The fruit fly entity instance.
• Returns: boolean — true if a valid soil target is found.

ShouldTargetPlant(inst, plant)

• Description: Checks whether a given plant can be safely targeted. Ensures no other entity (especially the leader) is already targeting it.
• Parameters:
  • inst (Entity): The fruit fly entity instance.
  • plant (Entity): The plant entity to evaluate.
• Returns: boolean — true if no conflict exists.

GetRunAwayTarget(inst)

• Description: Returns the current combat target to run away from (used by the RunAway behavior).
• Parameters:
  • inst (Entity): The fruit fly entity instance.
• Returns: Entity or nil — The combat target to avoid.

FruitFlyBrain:OnStart()

• Description: Initializes the behavior tree root node. Configures behaviors conditionally based on the lordfruitfly tag:
  • Lord fruit flies get: summon child node (with MinPeriod), attack staging (attack/dodge phases), and dodging during cooldown.
  • Regular fruit flies get: ChaseAndAttack with a simple CanTargetAndAttack condition.
• Parameters: None.
• Returns: nil.

Events & Listeners

None identified.

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