Shadowthrall Centipede Brain

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

Overview

This brain component governs the behavior of individual segments in the Shadowthrall Centipede entity. It implements a behavior tree that orchestrates two primary modes: seeking and consuming miasma (which can trigger body growth) and wandering when not actively feeding. The brain participates in a segment-level control negotiation system where segments compete for control based on their current intent—eating miasma has higher priority than wandering. When a segment gains control, it executes its behavior tree; otherwise, it waits in a requesting state.

Key interactions include the centipedebody component (for control status and segment growth), eater (for identifying edible miasma clouds), timer (to track feeding cooldowns), and knownlocations (for home position, though currently unused).

Usage example

Typically, this brain is automatically added and assigned to each Shadowthrall Centipede segment entity during prefab initialization. Modders should not need to instantiate it manually.

-- Not typically used directly by modders
-- The brain is attached automatically via the prefab's OnSpawn function:
inst:AddBrain("brains/shadowthrall_centipede_brain")

Dependencies & tags

Components used:

• centipedebody: SegmentHasControl(), GrowNewSegment()
• eater: CanEat(), GetEdibleTags()
• timer: TimerExists(), StartTimer()

Tags:

• shadowthrall_centipede (used in TestWanderPoint for spatial queries)

Properties

Property	Type	Default Value	Description
control_priority	integer	PRIORITY_BEHAVIOURS.WANDERING	Priority level for control negotiation. Set to EATING when actively consuming miasma, otherwise WANDERING.
miasma_counter	integer	0	Tracks consecutive miasma consumed. Reset after growth or feeding delay.
cached_rotation	number	nil	Cached forward direction used to compute interaction angle for miasma.
cached_forwardvector	Vector3	nil	Cached forward vector (recomputed when rotation changes).

Main functions

The brain class itself does not expose public methods beyond the constructor. All logic resides in nested helper functions used within the behavior tree.

ShadowThrallCentipedeBrain:OnStart()

• Description: Initializes the behavior tree. Sets up two major node groups: one for requesting control and one for executing behavior while in control. The root priority node decides between these based on whether the segment currently holds control.
• Parameters: None (part of the Brain class lifecycle).
• Returns: nil
• Error states: None. Relies on behavior tree infrastructure (PriorityNode, WhileNode, ConditionNode, DoAction, Wander) to manage transitions and execution.

CanInteractPosWithinAngle(inst, pos)

• Description: Helper that determines if a target position lies within the centipede segment's forward-facing interaction cone.
• Parameters:
  • inst (Entity): The segment entity whose forward direction is used.
  • pos (Vector3): The target position to test.
• Returns: boolean — true if within ANGLE_INTERACT_WIDTH degrees of the segment's forward direction.
• Error states: None.

GetHome(inst)

• Description: Provides the current position as the wandering home location. (The spawnpoint location lookup is commented out.)
• Parameters:
  • inst (Entity): The segment entity.
• Returns: Vector3 — The segment's current position.
• Error states: None.

TestForMiasma(item, inst)

• Description: Predicate used to filter valid miasma targets. Checks age, edibility, and angular proximity.
• Parameters:
  • item (Entity): Potential miasma cloud.
  • inst (Entity): The centipede segment.
• Returns: boolean
• Error states: Returns false if miasma is too new (<1 second alive), not edible, or outside the interaction angle.

FindValidMiasma(inst)

• Description: Scans nearby entities for a valid miasma target. Excludes miasma if the segment's current stategraph has the "busy" tag.
• Parameters:
  • inst (Entity).
• Returns: Entity? — First valid miasma entity found, or nil.
• Error states: Returns nil if no valid miasma exists within range or if the segment is "busy".

DoFindAndEatMiasmaAction(inst)

• Description: Creates a buffered action to eat a target miasma. On success, increments the miasma counter and triggers segment growth when the threshold (EAT_MIASMA_MAX) is reached.
• Parameters:
  • inst (Entity).
• Returns: BufferedAction? — Action if a target miasma exists, otherwise nil.
• Error states: Returns nil if no valid miasma target is found.

GetWanderDirection(inst)

• Description: Generates a random wander direction within +/- 90 degrees of the segment's current facing.
• Parameters:
  • inst (Entity).
• Returns: number — Angle in radians.
• Error states: None.

TestWanderPoint(pt)

• Description: Validates a potential wander destination to prevent overcrowding and hazardous placement (holes, under overhangs).
• Parameters:
  • pt (Vector3).
• Returns: boolean — true if no other segment is within 2 units, not near a hole, and on land.
• Error states: None.

TakeControlToEat(inst)

• Description: Requests control for eating. Sets priority to EATING.
• Parameters:
  • inst (Entity).
• Returns: boolean — true if a valid miasma target is found (and request succeeds), otherwise false.
• Error states: None.

TakeControlToWander(inst)

• Description: Requests control for wandering. Sets priority to WANDERING.
• Parameters:
  • inst (Entity).
• Returns: boolean — Always true.
• Error states: None.

Events & listeners

None. This component does not register or fire any events.