Horrorfuel

Based on game build 714014 | Last updated: 2026-03-05

Overview

horrorfuel is a prefabricated item (inventory item with local FX) used in DST for Wurt's shadow magic system. It serves two primary roles:

1. Local visual effects container — spawns and manages an animstate-based entity (core) that visually pulses based on the player's sanity.
2. Spellcasting item — when used, it triggers a spell (Wurt_MermSpellFn) that activates nearby shadow minions and consumes the item.

The component does not define a standalone component class but instead is the prefab definition. Its behavior is implemented directly in the fn() constructor.

Usage example

This is not a component to be added manually — it is a prefab. To use this item in gameplay, simply spawn or craft horrorfuel (typically via Wurt's unique recipes). In mod code, you may reference it via TheWorld:SpawnPrefab("horrorfuel").

-- Example: Spawn the horrorfuel item (non-visual on dedicated server)
local item = TheWorld:SpawnPrefab("horrorfuel")
if item ~= nil then
    -- Can be given to player inventory, used as spell item, etc.
    item.components.inventoryitem:OnPutInInventory(player.components.inventory)
end

Dependencies & tags

Components used:

• stackable
• inspectable
• fuel
• repairer
• waterproofer
• inventoryitem
• spellcaster

Tags added:

• waterproofer
• purehorror
• mermbuffcast
• FX (only on the local FX core entity)

Properties

Property	Type	Default Value	Description
core	Entity or nil	nil	Local-only visual FX entity (not replicated). Only created on clients/non-dedicated servers.
currentlight	number	0	Current light override intensity (smoothed).
targetlight	number	0	Target light override intensity (based on sanity).
highlightchildren	table	{ inst.core }	Used for highlighting logic in editor/UI (non-functional in gameplay).
scrapbook_anim	string	"scrapbook"	Animation name used when displayed in scrapbook.
lightcolour	table	{102/255, 16/255, 16/255}	RGB color of emitted light (normalized 0–1).
fxprefab	string	"horrorfuel_castfx"	Prefab name used when casting the spell.
castsound	string	"meta4/casting/shadow"	Sound event path played on spell cast.
_player	Entity or nil	nil	Internal reference to the currently watched player for sanity tracking.

Main functions

Wurt_MermSpellFn(inst, target, pos, doer)

• Description: Spell function executed when the item is used as a spell. It activates Wurt's shadow minions by applying the wurt_merm_planar debuff and cheering them, then destroys the item.
• Parameters:
  • inst (Entity) — The horrorfuel item instance.
  • target (Entity) — Target entity passed on cast (unused in this implementation).
  • pos (Vector3) — Target position (unused in this implementation).
  • doer (Entity) — The entity casting the spell (typically the player).
• Returns: Nothing.
• Error states: No explicit error handling; assumes doer.components.leader and minion components exist. If the item is not stackable, inst:Remove() is called directly.

CalcTargetLightOverride(player)

• Description: Computes the target light intensity for the local FX entity based on player sanity.
• Parameters:
  • player (Entity or nil) — The player whose sanity is being evaluated.
• Returns: Number in [0, 1] — 0 if sanity is ≥60% or no player; otherwise increases as sanity decreases to 0%.
• Error states: Returns 0 if player is nil, or if sanity replica is missing or not in insanity mode.

UpdateLightOverride(inst, instant)

• Description: Updates the AnimState light override on the FX entity. Uses linear interpolation unless instant is true.
• Parameters:
  • inst (Entity) — The FX entity (core).
  • instant (boolean) — If true, sets currentlight directly to targetlight.
• Returns: Nothing.

OnSanityDelta(player, data)

• Description: Event callback that instantly updates all active horrorfuel entities when sanity changes (except overtime).
• Parameters:
  • player (Entity) — The player whose sanity changed.
  • data (table) — Sanity change data (checks data.overtime).
• Returns: Nothing.

OnEntityWake(inst)

• Description: Registers the entity to monitor sanity changes and starts a periodic task to update light override.
• Parameters:
  • inst (Entity) — The entity being woken (either the main item or its core).
• Returns: Nothing.

OnEntitySleep(inst)

• Description: Stops monitoring and cancels the periodic task when the entity falls asleep.
• Parameters:
  • inst (Entity) — The entity falling asleep.
• Returns: Nothing.

CreateCore()

• Description: Helper to spawn and configure the local FX entity (core). Not a component function; used only by fn().
• Parameters: None.
• Returns: Entity — Non-networked, non-persistent FX entity.
• Error states: None.

Events & listeners

• Listens to: sanitydelta — updates FX lighting when player sanity changes.
• Listens to: onremove — clears the watched _player reference when the player is removed.
• Listens to: playeractivated — switches monitored player to the newly activated one.
• Pushes: None — this entity does not push events.