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Grassgekkobrain

Based on game build 714014 | Last updated: 2026-03-03

Overview​

Grassgekkobrain defines the behavior tree for the grassgekko entity, a small prey animal in DST. It prioritizes panic responses to electric fences and scaring entities (e.g., players), then falls back to fleeing or wandering. It uses the knownlocations component to determine a target for wandering behavior (specifically, the "herd" location).

Usage example​

local inst = CreateEntity()
inst:AddComponent("knownlocations")
-- ... populate knownlocations with "herd" ...
inst.brain = GrassgekkoBrain(inst)
inst.brain:OnStart()

Dependencies & tags​

Components used: knownlocations (accessed via inst.components.knownlocations:GetLocation("herd")) Tags: Uses the tag "scarytoprey" for one RunAway behavior; "player" for another. Uses NO_TAGS set ({"FX", "NOCLICK", "DECOR","INLIMBO", "stump", "burnt"}) to exclude those entities from avoidance.

Properties​

No public properties.

Main functions​

OnStart()​

  • Description: Initializes and assigns the behavior tree for the grassgekko. Sets up a priority node ordering behavior: panic triggers first, then flight from scary entities and players, and finally wandering.
  • Parameters: None.
  • Returns: Nothing.
  • Error states: Requires inst.components.knownlocations to be present and contain a "herd" location; otherwise, GetLocation("herd") returns nil, and wander behavior may malfunction.

Events & listeners​

None identified.

Behaviors and constants​

The following constants control behavior thresholds (all distances are in game units):

  • MIN_FOLLOW_DIST = 0, MAX_FOLLOW_DIST = 25, TARGET_FOLLOW_DIST = 6 — unused in current code.
  • MAX_WANDER_DIST = 8 — passed to Wander via GetWanderDistFn.
  • LEASH_RETURN_DIST = 15, LEASH_MAX_DIST = 30 — unused in current code.
  • AVOID_PLAYER_DIST = 7, AVOID_PLAYER_STOP = 12 — distance thresholds for fleeing players.
  • AVOID_DIST = 7, AVOID_STOP = 12 — distance thresholds for fleeing from other "scarytoprey" entities.
  • NO_TAGS — list of tags to ignore during avoidance logic.
  • GetWanderDistFn(inst) — returns MAX_WANDER_DIST (8) as a dynamic wander range.

The behavior tree root uses PriorityNode with these behaviors in order:

  1. BrainCommon.PanicTrigger — immediate panic reaction (e.g., to fire).
  2. BrainCommon.ElectricFencePanicTrigger — panic when near electrified fences.
  3. RunAway(self.inst, "scarytoprey", 7, 12, ...) — flee from entities tagged "scarytoprey".
  4. RunAway(self.inst, "player", 7, 12, nil, nil, NO_TAGS) — flee from players, excluding entities with NO_TAGS.
  5. Wander(self.inst, ...) — wander toward the "herd" location returned by knownlocations:GetLocation("herd"), up to 8 units away.