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Mermthrone

Based on game build 714014 | Last updated: 2026-03-06

Overview​

The mermthrone prefab implements the Merm King’s throne structure, which appears in the Forest world. It exists in two forms: an unoccupied, buildable construction stage (mermthrone_construction) and a fully built throne (mermthrone). When the Merm King appears, the throne is "occupied", becoming indestructible and immune to fire and propagator damage, and updates its minimap icon accordingly. The structure supports construction, hammering, burning, and deconstruction, emitting world-level events (onthronebuilt, onthronedestroyed) for orchestration.

The component logic is embedded directly in the fn (for built throne) and construction_fn (for construction site) functions, and uses several standard components (workable, burnable, lootdropper, constructionsite) to handle game mechanics.

Usage example​

-- Example: Spawn a throne and check if it’s occupied by the Merm King
local throne = SpawnPrefab("mermthrone")
throne.Transform:SetPosition(0, 0, 0)

-- Check occupied status via MermKingManager (requires mastersim)
if TheWorld.components.mermkingmanager then
    if TheWorld.components.mermkingmanager:IsThrone(throne) then
        print("Throne is occupied!")
    end
end

Dependencies & tags​

Components used: workable, burnable, lootdropper, constructionsite, inspectable, propagator (removed when occupied), soundemitter, animstate, transform, minimapentity, network, hauntable Tags added/removed: Adds mermthrone to built throne; constructionsite to construction stage. Removes propagator/burnable when occupied.

Properties​

No public properties are defined or modified directly in this file.

Main functions​

The logic is implemented in local callback functions bound to component events and entity lifecycle hooks. No methods are exported as standalone public functions, but the following are core internal helpers:

OnConstructed(inst, doer)​

  • Description: Called when construction is completed. Verifies material requirements; if satisfied, replaces the construction site with mermthrone, emits build sound, and fires onthronebuilt.
  • Parameters: inst (Entity) — the construction site entity; doer (Entity) — builder (unused).
  • Returns: Nothing.
  • Error states: Does not proceed unless all materials for CONSTRUCTION_PLANS[inst.prefab] are met.

ondeconstruct_common(inst)​

  • Description: Fires onthronedestroyed event when a throne (occupied or not) is deconstructed.
  • Parameters: inst (Entity) — the throne entity.
  • Returns: Nothing.

onburnt_common(inst)​

  • Description: Fires onthronedestroyed event when the throne is fully burnt.
  • Parameters: inst (Entity) — the throne entity.
  • Returns: Nothing.

onhammered_common(inst, worker)​

  • Description: Handles hammering logic for both construction and regular throne: extinguishes fire (if burning), drops loot, spawns collapse FX.
  • Parameters: inst (Entity); worker (Entity) — the hammerer.
  • Returns: Nothing.

onhammered_construction(inst, worker)​

  • Description: Hammer callback for construction site. Calls onhammered_common, drops all construction materials, and removes the entity.
  • Parameters: inst (Entity); worker (Entity).
  • Returns: Nothing.

onhammered_regular(inst, worker)​

  • Description: Hammer callback for built throne. Calls onhammered_common, fires onthronedestroyed, and removes the entity.
  • Parameters: inst (Entity); worker (Entity).
  • Returns: Nothing.

onhit_construction(inst, worker)​

  • Description: Called on partial hammer hits during construction. Plays hit animation, cancels construction.
  • Parameters: inst (Entity); worker (Entity).
  • Returns: Nothing.
  • Error states: Does nothing if entity is burnt.

onconstruction_built(inst)​

  • Description: Called when construction finishes. Prevents collisions, plays placement animation/sound, and prevents future construction.
  • Parameters: inst (Entity) — now a mermthrone.
  • Returns: Nothing.

onsave(inst, data)​

  • Description: Serializes burning state. Stores data.burnt = true if currently burnt or burning and ignoring fuel.
  • Parameters: inst (Entity); data (table) — save data table.
  • Returns: Nothing.

onload(inst, data)​

  • Description: Restores burnt state on load. Calls onburnt callback if saved as burnt.
  • Parameters: inst (Entity); data (table | nil) — loaded data.
  • Returns: Nothing.

OnMermKingCreated(inst, data)​

  • Description: Reacts to Merm King spawn event. Disables workability, removes fire propagator, removes burnable component, and updates minimap icon.
  • Parameters: inst (Entity) — the throne; data (table) — event data containing throne.
  • Returns: Nothing.

OnMermKingDestroyed(inst, data)​

  • Description: Reacts to Merm King removal. Re-enables workability, restores burnable and propagator, sets canlight, and resets minimap icon.
  • Parameters: inst (Entity); data (table) — event data containing throne.
  • Returns: Nothing.

OnThroneRemoved(inst)​

  • Description: Fallback listener for when throne is removed indirectly (e.g., via Remove()). Fires onthronedestroyed if throne is registered with mermkingmanager.
  • Parameters: inst (Entity).
  • Returns: Nothing.

Throne_Initialize(inst)​

  • Description: Deferred initializer run on startup (after OnLoad). Checks if a Merm King already exists and triggers OnMermKingCreated.
  • Parameters: inst (Entity).
  • Returns: Nothing.

invalid_placement_fn(player, placer)​

  • Description: Validation function for placement. Alerts player via talker if placement blocked (e.g., invalid terrain).
  • Parameters: player (Entity | nil); placer (Entity | nil).
  • Returns: Nothing (early return on mouse_blocked).

Events & listeners​

  • Listens to:
    • onburnt — calls onburnt_common.
    • ondeconstructstructure — calls ondeconstruct_common.
    • onmermkingcreated — triggers OnMermKingCreated if throne matches data.throne.
    • onmermkingdestroyed — triggers OnMermKingDestroyed if throne matches data.throne.
    • onremove — triggers OnThroneRemoved if throne is registered in mermkingmanager.
    • onbuilt (construction) — triggers onconstruction_built.
  • Pushes:
    • onthronebuilt — after successful construction.
    • onthronedestroyed — on destruction via hammer, burn, deconstruct, or removal.