Add a BaseInventoryComponent to your player and it can carry things. It keeps items in slots, remembers which one is deployed, and handles picking up, dropping and switching.
Slots
MaxSlots sets how many slots there are, and Behaviour sets how they work:
| Behaviour | Description |
|---|---|
| Hotbar | One item per slot, like Rust or Minecraft. When an item's preferred slot is taken it goes to the first empty one. |
| Buckets | Slots are categories and any number of items share one, like GMod or Half-Life. Items always land in their preferred slot. |
Items ask for a slot with their PreferredSlot property, and sort within a bucket by SlotOrder.
Picking things up
PickupMode controls how the inventory takes items lying in the world:
| Mode | Description |
|---|---|
| None | It doesn't. Call PickupWorldItem from your own code when you want one taken. |
| Touch | Walking near a world item picks it up, like GMod or Quake. |
| Use | The player presses use on the item to take it. |
With AutoSwitchOnPickup on, picking up something better than what's held deploys it. Better means a higher Value, which you set on each item.
Picking up a weapon the player already has doesn't give a second copy. The duplicate donates its ammo to the reserve instead.
Loadouts
Turn the Loadout feature on to have starting gear. StartingItems is a list of prefabs given when the inventory starts, along with any StartingAmmo. Call GiveLoadout() yourself when you want to give it again, on respawn for example.
Switching, dropping, removing
Switch( item ) deploys an item, Drop( item ) throws it out into the world, Remove( item ) destroys it. Query what's held with Items, ActiveItem, GetSlot( n ) and GetItem<T>().
var inventory = player.GetComponent<BaseInventoryComponent>();
var item = inventory.ActiveItem;
if ( item.IsValid() )
Log.Info( $"Holding {item.DisplayName} in slot {item.Slot}" );
All of this is host authoritative. The owning client can call these too, they route through the host.
Ammo
Reserve ammo lives on the inventory, not on the weapon, so two guns that share an ammo type share their reserve. An ammo type is a BaseAmmoResource asset with a name, an icon and a max reserve. Create one from the Asset Browser.
GetAmmo, GiveAmmo and TakeAmmo on the inventory read and change the pool.
Making an item
BaseInventoryItem is anything an inventory can hold. On its own it's a pickup with a display name, an icon and a slot preference. Override its hooks to give it behaviour:
OnEquipped/OnHolsteredrun on every peer when it's deployed or put away.OnControlruns each frame on the owning client while it's deployed. Read input here.OnAdded/OnRemovedrun on the host when it enters or leaves an inventory.OnDropplaces the item in the world when dropped. Return false to refuse the drop.
:::info
There's no built in inventory or hotbar UI. Build your own from Items, GetSlot and ActiveItem. They're synced and cheap enough to read from HUD code every frame.
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