Cave Vents

Based on game build 714014 | Last updated: 2026-03-04

Overview

cave_vents.lua defines the cave_vent_rock prefab, an interactive environmental entity that dynamically adjusts its spewing behavior based on world conditions (e.g., rift activity, toadstool gas emission) and player interaction. It integrates with the heater, lootdropper, workable, timer, inspectable, and miasmamanager components to simulate geothermal activity, spew miasma clouds, and respond to mining. The vent type is computed by GetVentType() and can be HOT, MIASMA, COLD, GAS, or NONE, with behavior handlers registered in vent_type_fns.

Usage example

local vent = SpawnPrefab("cave_vent_rock")
if vent and vent.Transform then
    vent.Transform:SetPosition(x, y, z)
    vent.UpdateVentilation() -- Recompute spewing behavior based on world state
    if vent.components.workable then
        print("Vent work left:", vent.components.workable.workleft)
    end
end

Dependencies & tags

Components used: heater, lootdropper, inspectable, workable, timer, miasmamanager, riftspawner, toadstoolspawner.
Tags: Adds boulder, HASHEATER. Uses conditional tag miasma_venter for MIASMA-type vents.

Properties

Property	Type	Default Value	Description
ventilation_type	number	VENT_TYPES.NONE	Current vent type (see VENT_TYPES constants).
set_loot_table	string or nil	nil	Loot table override set during world generation.
_gaslevel	number	0	Internal gas buildup level (used for gas vents).
_gasuptask / _gasdowntask	Task or nil	nil	Periodic tasks managing gas buildup and decay.

Main functions

UpdateVentilation(inst, is_populating, vent_type)

• Description: Recomputes and applies the current vent type. Stops old vent effects and triggers new ones (e.g., start miasma spewing or hot air).
• Parameters: inst (Entity) — the vent entity; is_populating (boolean) — true if called during world gen initialization; vent_type (number, optional) — override vent type (default: computed via GetVentType).
• Returns: Nothing.
• Error states: Safely handles missing vent function definitions via vent_type_fns[old_vent_type].on_stop_venting nil checks.

GetHeat(inst)

• Description: Returns the heat output value for the heater component based on the current vent type.
• Parameters: inst (Entity).
• Returns: number — heat magnitude (e.g., TUNING.CAVE_VENTS.HEAT.HOT_ACTIVE).
• Error states: Sets heater thermics (exothermic/endothermic) to false for non-active types.

ForceSpew(inst)

• Description: Immediately triggers spew timers for all vent types by setting their remaining time to FRAMES.
• Parameters: inst (Entity).
• Returns: Nothing.

CustomOnHaunt(inst, haunter)

• Description: Custom haunt reaction; with 50% chance, forces a spew on haunting.
• Parameters: inst (Entity), haunter (Entity).
• Returns: boolean — true if haunting should succeed (i.e., a spew occurred), otherwise false.

OnSave(inst, data)

• Description: Serializes state to data. Saves ventilation_type and set_loot_table.
• Parameters: inst (Entity), data (table).
• Returns: Nothing.

OnLoad(inst, data)

• Description: Restores vent state during load. Does not re-initialize timers immediately (handled by scheduled tasks).
• Parameters: inst (Entity), data (table).
• Returns: Nothing.

Events & listeners

• Listens to: timerdone — triggers OnTimerDone to restart vent spew timers.
• Pushes: OnSave and OnLoad are custom hooks on inst (not pushed events).
• World listeners: Subscribes to ms_riftaddedtopool, ms_riftremovedfrompool, toadstoolstatechanged, and toadstoolkilled on TheWorld to recompute ventilation when rift/toadstool states change.