Ghostbrain

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

Overview

GhostBrain is a behavior tree (BT) implementation that defines how ghost entities (e.g., ghost) decide whether to follow or wander. It prioritizes chasing a valid living character within range, but retreats or dissipates if no suitable target is found. The brain uses the behavior tree framework to orchestrate state-driven actions: a high-priority follow action while a target exists, and a fallback wander-then-dissipate sequence otherwise.

Key relationships:

• Uses Combat component (ghost.components.combat:TargetIs) to determine active targeting state.
• Uses Health component (target.components.health:IsDead()) to verify target viability.

Dependencies & Tags

• Components used:
  • health: Checked via IsDead() for target validation.
  • combat: Checked via TargetIs() for mutual targeting during ghost-friendly interactions.
• Tags:
  • TARGET_MUST_TAGS = \{"character"\}: Targets must have this tag.
  • TARGET_CANT_TAGS = \{"INLIMBO", "noauradamage"\}: Targets with these tags are excluded.

Properties

Property	Type	Default Value	Description
followtarget	GameObject?	nil	Holds the currently selected character to follow; cleared if target becomes invalid (e.g., dead, out of range, or invisible).

Main Functions

GhostBrain:OnStart()

• Description: Initializes the behavior tree root node. Sets up a priority-based behavior: first attempts to follow a valid target if found, otherwise executes a sequence of waiting 10 seconds while wandering, then dissipating (transitioning to "dissipate" state in the SG).
• Parameters: None.
• Returns: None.

GetFollowTarget(ghost)

• Description: Calculates and updates the ghost's current follow target. Clears ghost.brain.followtarget if it becomes invalid, then searches for the first living character within 10 units (by distance squared TUNING.GHOST_FOLLOW_DSQ) that meets targeting rules. Respects ghost-friendly tags ("ghostlyfriend" or "abigail"), requiring mutual targeting before following them. Non-ghost-friendly characters are followed unconditionally if alive and visible.
• Parameters:
  • ghost: GameObject — The ghost entity whose brain is computing the target.
• Returns: GameObject? — The selected target if found, otherwise nil.

Events & Listeners

None. GhostBrain does not register or dispatch events; it operates solely via behavior tree evaluation.