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Backpack

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

Overview​

The backpack prefab implements a wearable inventory container with support for skin-specific visual follow effects (e.g., animation-synced FX attached to the owner during equipping). It integrates closely with the equippable, container, burnable, and inventoryitem components. It serves as a core wearable item in the game's crafting and inventory systems, opening its container UI when equipped and managing its visual representation (including skin overrides and follow FX) on equip/unequip.

Usage example​

local backpack = SpawnPrefab("backpack")
backpack.Transform:SetPosition(inst.Transform:GetWorldPosition())
inst.components.inventory:AddItem(backpack, true)

-- When equipped, the backpack's container opens and skin follow FX attach to the owner

Dependencies & tags​

Components used: inspectable, inventoryitem, equippable, container, burnable, propagator, highlightchild, colouradder, bloomer, follower
Tags: Adds backpack and FX (for backpack_swap_fx sub-prefab); no tag removal or checking logic in core code.

Properties​

No public properties are initialized directly on the backpack entity instance beyond component internal states. Skin-related behavior is exposed via callbacks in inst.backpack_skin_fns (modder-extendable).

Main functions​

The backpack prefab is primarily a data-driven entity defined via its fn() constructor. Custom behavior is exposed through callback hooks and event listeners. Key internal functions:

onequip(inst, owner)​

  • Description: Invoked when the backpack is equipped. Sets up skin overrides, attaches follow FX, and opens the container to the owner.
  • Parameters:
    inst (entity) – The backpack entity.
    owner (entity) – The entity equipping the backpack.
  • Returns: Nothing.

onunequip(inst, owner)​

  • Description: Invoked when the backpack is unequipped. Detaches follow FX, reattaches idle FX, clears animation overrides, and closes the container.
  • Parameters:
    inst (entity) – The backpack entity.
    owner (entity) – The entity unequipping the backpack.
  • Returns: Nothing.

onburnt(inst)​

  • Description: Called when the backpack is fully burnt. Drops all container contents, closes the container, spawns an ash prefab, and removes the backpack.
  • Parameters: inst (entity) – The backpack entity.
  • Returns: Nothing.

onignite(inst)​

  • Description: Called when the backpack is ignited. Disables container opening by setting canbeopened = false.
  • Parameters: inst (entity) – The backpack entity.
  • Returns: Nothing.

onextinguish(inst)​

  • Description: Called when the backpack is extinguished. Re-enables container opening by setting canbeopened = true.
  • Parameters: inst (entity) – The backpack entity.
  • Returns: Nothing.

OnBackpackSkinChanged(inst, skin_build)​

  • Description: Handler called when the backpack’s skin changes. Resets and reinitializes all follow FX (idle and equip). Removes old FX and recreates them with the new skin build.
  • Parameters:
    inst (entity) – The backpack entity.
    skin_build (string or nil) – The new skin build name.
  • Returns: Nothing.

ForEachSkinFollowFx(inst, cb, ...)​

  • Description: Utility to iterate over all active skin follow FX (idle and equipped). Useful for applying changes en masse (e.g., colour/bloom updates).
  • Parameters:
    inst (entity) – The backpack entity.
    cb (function) – Callback invoked with signature cb(inst, fx, ...).
    ... (any) – Additional arguments passed to cb.
  • Returns: Nothing.

OnSave(inst, data) and OnLoad(inst, data, ents)​

  • Description: Serialization hooks delegated to inst.backpack_skin_fns.onsave and inst.backpack_skin_fns.onload if present. Allows modded skins to persist/restore state.
  • Parameters:
    inst (entity) – The backpack entity.
    data (table) – Serialization table.
    ents (table, only in OnLoad) – Entity mapping.
  • Returns: Nothing.

Events & listeners​

  • Listens to:
    equipskinneditem (pushed via owner:PushEvent(...))
    unequipskinneditem (pushed via owner:PushEvent(...))
    onremove – used internally via ListenForEvent in Bloomer.AttachChild/DetachChild to clean up colour/bloom attachments.
  • Pushes:
    equipskinneditem with inst:GetSkinName() when equipped with a skin.
    unequipskinneditem with inst:GetSkinName() when unequipped with a skin.
    onclose – fired via Container.Close(...).
  • Component-internal listeners:
    colouradder and bloomer components listen for onremove on FX entities to detach cleanly.