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Mermhouse

Based on game build 7140014 | Last updated: 2026-03-06

Overview​

The mermhouse prefab represents a structure in DST that functions as a Merm spawner. It manages a pool of Merm units and regenerates them over time, especially at night (unless the game is in Winter). It interacts with several core systems: childspawner (for minion management), burnable (for fire behavior), lootdropper (for demolition rewards), workable (for hammering interaction), and hauntable (for ghost haunting). The crafted variant also interfaces with the deployhelper and worldsettingstimer components to support dynamic spawning rate adjustments via Wurt's offering pot.

Usage example​

-- Creating a pristine Mermhouse instance
local house = Prefab("mermhouse", ...)

-- Attaching and configuring child spawner
house:AddComponent("childspawner")
house.components.childspawner.childname = "merm"
house.components.childspawner:SetSpawnPeriod(TUNING.MERMHOUSE_RELEASE_TIME)
house.components.childspawner:SetMaxChildren(TUNING.MERMHOUSE_MERMS)

-- Enabling loot and burn behavior
house:AddComponent("lootdropper")
house.components.lootdropper:SetLoot({ "boards", "rocks", "pondfish" })
MakeMediumBurnable(house)

Dependencies & tags​

Components used: burnable, childspawner, combat, deployhelper, hauntable, inspectable, lootdropper, updatelooper, workable, worldsettingstimer, health (via MakeMediumBurnable, MakeLargePropagator, MakeObstaclePhysics).

Tags added/checked: structure, CLASSIFIED, NOCLICK, placer, burnt.
The component also checks for character, merm, playerghost, INLIMBO in haunt targeting logic.

Properties​

No public properties are defined on the mermhouse prefab itself — it uses component properties exposed via inst.components.X. Key component-based properties used include:

  • childspawner.childname (string) — prefab name of spawned Merm.
  • childspawner.childreninside (integer) — current count of available children in the house.
  • childspawner.canemergencyspawn (boolean) — whether emergency spawning is enabled.
  • hauntable.value (number) — haunt value used when a ghost interacts.

Main functions​

MakeMermHouse(name, common_postinit, master_postinit)​

  • Description: Factory function that constructs and returns a Prefab for a Mermhouse. Accepts optional per-instance post-initialization callbacks.
  • Parameters:
    • name (string) — name of the prefab ("mermhouse" or "mermhouse_crafted").
    • common_postinit (function | nil) — invoked on both server and client during entity creation.
    • master_postinit (function | nil) — invoked only on master sim (server) after components are added.
  • Returns: Prefab — fully configured prefab definition.

OnEnableHelper(inst, enabled, recipename, placerinst)​

  • Description: Enables or disables the placement helper visual ring (e.g., during offering pot crafting). Used only by crafted variant on non-dedicated servers.
  • Parameters:
    • inst (Entity) — the entity instance.
    • enabled (boolean) — whether to show/hide the helper ring.
    • recipename (string) — name of the recipe being crafted.
    • placerinst (Entity) — optional reference to the placer entity used for distance checks.
  • Returns: Nothing.

onhammered(inst, worker)​

  • Description: Handles destruction of the house via hammering, extinguishing fire, dropping loot, spawning collapse FX, and removing the entity.
  • Parameters:
    • inst (Entity) — the house entity.
    • worker (Entity) — the entity performing the hammer action.
  • Returns: Nothing.

onhit(inst, worker)​

  • Description: Triggered when the house is damaged (but not destroyed), releases all Merm children and plays a hit animation.
  • Parameters:
    • inst (Entity) — the house entity.
    • worker (Entity) — the entity striking the house.
  • Error states: No effect if inst:HasTag("burnt").

StartSpawning(inst), StopSpawning(inst)​

  • Description: Enable/disable automatic child spawing based on world state (isday, iswinter, burnt). Called by OnIsDay callback.
  • Parameters:
    • inst (Entity) — the house entity.
  • Returns: Nothing.

OnSpawned(inst, child)​

  • Description: Callback fired when a Merm leaves the house. Plays a door sound and may stop spawning if daytime and children remain.
  • Parameters:
    • inst (Entity) — the house entity.
    • child (Entity) — the spawned Merm.
  • Returns: Nothing.

OnGoHome(inst, child)​

  • Description: Callback fired when a Merm returns home. Plays a door sound and restarts spawning if no children remain outside.
  • Parameters:
    • inst (Entity) — the house entity.
    • child (Entity) — the returning Merm.
  • Returns: Nothing.

OnIsDay(inst, isday)​

  • Description: World state listener that toggles spawning on/off based on time of day. Stops spawning at day, starts at night (unless burnt or in winter).
  • Parameters:
    • inst (Entity) — the house entity.
    • isday (boolean) — current daylight state.
  • Returns: Nothing.

OnHaunt(inst)​

  • Description: Handles ghost haunt attempts: spawns a Merm at the house via onhit, if haunt chance passes and a valid target is nearby.
  • Parameters:
    • inst (Entity) — the house entity.
  • Returns: boolean — true if haunt succeeded, false otherwise.

UpdateSpawningTime(inst, data)​

  • Description: Adjusts regen and spawn periods dynamically based on kelp offering count in the nearby offering pot. Used only by crafted variant.
  • Parameters:
    • inst (Entity) — the crafted house entity.
    • data (table) — event payload containing inst, count of offerings.
  • Returns: Nothing. Early exit if data invalid or offering pot out of range.

Events & listeners​

  • Listens to: onignite, burntup, isday (via WatchWorldState), onbuilt, ms_updateofferingpotstate (crafted variant only).
  • Pushes: None — relies on component-level events (childspawner, burnable, workable) for state updates.