Shadowthrall Horns Brain

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

Overview

The ShadowThrallHornsBrain component implements the behavior tree for the Shadowthrall Horns entity, which functions as a coordinated sub-division of the larger Shadowthrall boss. It manages combat prioritization, sequential attack coordination (especially with "hands" and "wings" teammates), and positional behavior (wandering, targeting, formation positioning). This brain integrates with several components: Combat for attack state and target tracking, EntityTracker for referencing teammates, and KnownLocations for spawn-based homing.

Usage example

This brain is typically attached to an entity instance during prefab initialization and does not require manual method calls. The behavior tree is constructed automatically when the entity enters its StateGraph.

inst:AddComponent("shadowthrallhornsbrain")
-- The component is added implicitly via prefabs that use this brain class
-- and the behavior tree starts running when the entity's stategraph begins.

Dependencies & tags

Components used:

• combat: accessed via inst.components.combat.target, inst.components.combat:InCooldown(), inst.components.combat:TargetIs(target).
• entitytracker: accessed via inst.components.entitytracker:GetEntity(name).
• knownlocations: accessed via inst.components.knownlocations:GetLocation(name).
• stategraph: referenced via inst.sg:HasStateTag("jumping"), inst.sg.mem.lastattack.

Tags: None identified (no tags added/removed by this component directly).

Properties

Property	Type	Default Value	Description
inst.formation	number or nil	nil	Angle offset (in degrees) used to compute formation position relative to the target; only used if non-nil.
bt	BT	nil (assigned in OnStart)	The BehaviorTree root instance constructed during OnStart() initialization.

Main functions

OnStart()

• Description: Initializes the behavior tree root node for the Shadowthrall Horns entity. Constructs a hierarchical priority tree that handles turn-based attack sequencing, movement toward targets, formation positioning, wandering, and attack triggering.
• Parameters: None.
• Returns: None.
• Error states: This function must be called exactly once during entity initialization (typically via the StateGraph). If inst.formation is set but target position is unavailable, formation calculation silently returns nil.

GetHome(inst)

• Description: Helper function that retrieves the spawn point location for use in wandering or leashing logic.
• Parameters:
  • inst: Entity instance.
• Returns: vector3 or nil — position of the location named "spawnpoint" from KnownLocations, or nil if not found.
• Error states: Returns nil if "spawnpoint" has not been registered in KnownLocations.

GetTarget(inst)

• Description: Retrieves the current combat target of the entity.
• Parameters:
  • inst: Entity instance.
• Returns: Entity instance or nil — the value of inst.components.combat.target.
• Error states: May return nil if no target is set.

GetTargetPos(inst)

• Description: Returns the current world position of the combat target.
• Parameters:
  • inst: Entity instance.
• Returns: vector3 or nil — position of the target, or nil if no target exists.
• Error states: Returns nil if target is nil or target lacks GetPosition().

GetFormationPos(inst)

• Description: Calculates a position offset from the target based on the entity's configured inst.formation angle and a fixed distance (FORMATION_DIST = 6).
• Parameters:
  • inst: Entity instance.
• Returns: vector3 or nil — offset position if inst.formation is set and target position is available; otherwise nil.
• Error states: May return nil if inst.formation is nil, or if GetTargetPos(inst) returns nil.

IsTheirTurnToAttack(inst, teammate)

• Description: Determines whether a specified teammate (teammate name such as "hands" or "wings") should attack before this entity based on attack timestamp comparison and shared target.
• Parameters:
  • inst: Entity instance.
  • teammate: string — name key for the teammate entity as registered in EntityTracker.
• Returns: boolean — true if the teammate is present, has a valid StateGraph memory with a recorded lastattack, and attacked earlier than this entity while sharing the same target.
• Error states: Returns false if teammate is nil, missing StateGraph, missing lastattack, missing Combat component, or has a different target.

IsMyTurnToAttack(inst)

• Description: Checks whether this entity is allowed to initiate an attack, considering both its own combat cooldown and precedence over teammates.
• Parameters:
  • inst: Entity instance.
• Returns: boolean — true if attack is not on cooldown and no teammate with precedence has attacked more recently.
• Error states: Returns false if currently in attack cooldown or if a teammate's turn is active per IsTheirTurnToAttack.

IsTarget(inst, target)

• Description: Convenience wrapper around Combat:TargetIs.
• Parameters:
  • inst: Entity instance.
  • target: Entity instance — the entity to compare against the current combat target.
• Returns: boolean — true if target matches inst.components.combat.target.
• Error states: Returns false if target is nil or mismatched.

Events & listeners

• Listens to: None (this brain does not register its own event listeners; it uses StateGraph memory and component callbacks).
• Pushes:
  • "doattack" — pushed via inst:PushEvent("doattack", { target = ... }) when the entity’s turn arrives and attack conditions are met (inside ForceAttack node). This event triggers the actual combat action sequence.

The "doattack" event is expected to be handled elsewhere, typically by combat-related StateGraph states or prefabs referencing the entity's attack logic.