Inventory

Overview

All Out provides a player inventory API that allows you to create items, give them to players, and for players to arrange, use, and drop items in your game.

There are three core concepts:

• Item definitions (Item_Definition): what an item is (name/icon/stacking + your own fields)

• Item instances (Item_Instance): an actual stack in the world/in an inventory

• Inventories (Inventory): a container of slots that holds item instances

Every player has a built-in inventory at player.default_inventory.

Persistence

If you'd like player inventories to be automatically saved across game sessions, enable the "Auto Save Player Inventory" box in the Edit -> Game Settings section of the editor

Inventory API reference

Item_Definition_Desc :: struct {
    id:         string;
    name:       string;
    icon:       Texture_Asset;
    stack_size: s64;    // 1 = not stackable, -1 = infinite
    tier:       Item_Tier;
}

Items :: struct {
    // Inventories
    create_inventory  :: proc(unique_id: string, capacity: s64) -> Inventory;
    destroy_inventory :: proc(inventory: Inventory) -> bool;
    set_capacity      :: proc(inventory: Inventory, capacity: s64);

    // Item definitions + instances
    register_item_definition :: proc(desc: Item_Definition_Desc, $Definition_Type: typeid = Item_Definition, instance_type: typeid = Item_Instance) -> Definition_Type;
    create_item_instance     :: proc(definition: Item_Definition, count: s64 = 1) -> Item_Instance;
    create_item_instance     :: proc(definition: Item_Definition, $T: typeid, count: s64 = 1) -> T;
    destroy_item_instance    :: proc(instance: Item_Instance, count: s64 = -1);

    // Moving items around
    can_move_item_to_inventory                  :: proc(instance: Item_Instance, inventory: Inventory, will_destroy_item: ref bool) -> bool;
    move_item_to_inventory                      :: proc(instance: Item_Instance, inventory: Inventory);
    move_as_many_items_as_possible_to_inventory :: proc(instance: Item_Instance, inventory: Inventory, destroyed_item: ref bool) -> s64;
    remove_item_from_inventory                  :: proc(instance: Item_Instance, inventory: Inventory);
    can_swap_items                              :: proc(inventory_a: Inventory, inventory_b: Inventory, slot_a: s64, slot_b: s64) -> bool;
    swap_items                                  :: proc(inventory_a: Inventory, inventory_b: Inventory, slot_a: s64, slot_b: s64);

    // Queries
    calculate_room_in_inventory_for_item :: proc(definition: Item_Definition, inventory: Inventory) -> s64;
    destroy_all_items :: proc(inventory: Inventory);

    // UI (optional)
    draw_inventory :: proc(rect: Rect, inventory: Inventory, options: Inventory_Draw_Options) -> bool;
    draw_hotbar    :: proc(player: Player, inventory: Inventory, options: Inventory_Draw_Options) -> Draw_Hotbar_Result;
}

Inventory :: class : Inventory_Base {
    get_item :: proc(inventory: Inventory, index: s64) -> Item_Instance;
}

Item_Definition :: class : Item_Definition_Base {
    get_name :: method() -> string;
    get_id   :: method() -> string;
    get_icon :: method() -> Texture_Asset;
}

Item_Instance :: class : Item_Instance_Base {
    get_definition :: method() -> Item_Definition;
}

Quick start (register + give an item)

Register item definitions once in ao_before_scene_load, then create instances and move them into a player’s inventory.

// Optional: custom item types
Weapon_Definition :: class : Item_Definition {
    damage: s64;
}

Weapon_Item :: class : Item_Instance {
    durability: s64 @ao_serialize; // @ao_serialize makes it automatically save this field across sessions
}

sword_defn: Weapon_Definition;

ao_before_scene_load :: proc() {
    sword_defn = Items.register_item_definition(
        {id="sword", name="Iron Sword", icon=get_asset(Texture_Asset, "icons/sword.png"), stack_size=1, tier=.COMMON},
        Weapon_Definition,
        Weapon_Item
    );
    sword_defn.damage = 10;
}

give_sword :: proc(player: Player) {
    item := Items.create_item_instance(sword_defn, Weapon_Item);

    will_destroy: bool;
    if Items.can_move_item_to_inventory(item, player.default_inventory, ref will_destroy) {
        item.durability = 100;
        Items.move_item_to_inventory(item, player.default_inventory);
    }
    else {
        // Inventory full → destroy the instance we created
        Items.destroy_item_instance(item);
    }
}

Displaying the hotbar

To show the standard inventory hotbar UI on screen, call Items.draw_hotbar inside your Player's ao_late_update method. Without it, the inventory system works behind the scenes but the player won't see it!

Player :: class : Player_Base {
    ao_late_update :: method(dt: float) {
        if this->is_local_or_server() {
            draw_player_hotbar(this);
        }
    }
}

draw_player_hotbar :: proc(player: Player) {
    options := Inventory_Draw_Options.default();
    result := Items.draw_hotbar(player, player.default_inventory, options);

    // result.selected_item is the currently highlighted item (or null)
    // result.inventory_open tells you if the full bag UI is showing
}

Items.draw_hotbar handles the entire hotbar + bag toggle UI for you. It returns a Draw_Hotbar_Result with selected_item, selected_item_index, inventory_open, and dropped_item fields.

Checking if a player already has an item

A common pattern is to give an item only if the player doesn't already have one:

player_has_item :: proc(player: Player, definition: Item_Definition) -> bool {
    inv := player.default_inventory;
    for i: 0..inv.capacity-1 {
        item := inv->get_item(i);
        if item != null && item->get_definition() == definition {
            return true;
        }
    }
    return false;
}

give_sword_if_needed :: proc(player: Player) {
    if player_has_item(player, sword_defn) return;
    give_sword(player);
}

You can also check how much room is left for a specific item type before creating it:

room := Items.calculate_room_in_inventory_for_item(sword_defn, player.default_inventory);
if room > 0 {
    give_sword(player);
}

Custom Inventories

You can create inventories that aren’t tied to a player, for things like:

• Chests / storage containers

• Fish/mob teams

chest_inventory := Items.create_inventory("chest_01", 12);

To access items:

for i: 0..chest_inventory.capacity-1 {
    item := chest_inventory->get_item(i);
    if item == null continue;
    defn := item->get_definition();
    log_info("Slot %: %", {i, defn->get_name()});
}

Dropped Items

If you want players to drop items into the world (and let other players pick them up), use the dropped items system:

import "core:dropped_items"

Spawning a dropped item

item := Items.create_item_instance(sword_defn, Weapon_Item);
dropped := Dropped_Item.spawn(player.entity.world_position, item);

Drop animation + snapping to navmesh

server_rng: u64;

dropped->do_spawn_animation(ref server_rng, navmesh); // navmesh is optional

Handling drag-drop from the hotbar UI

If you use Items.draw_hotbar, players can drag an item out of the UI to drop it. Dropped_Item.handle_dropped_item removes it from the inventory and spawns a dropped item entity.

result := Items.draw_hotbar(player, player.default_inventory, Inventory_Draw_Options.default());

dropped: Dropped_Item;
if Dropped_Item.handle_dropped_item(result, player.entity.world_position, ref dropped) {
    dropped->do_spawn_animation(ref server_rng, navmesh);
}

Dropped items automatically despawn over time (with a warning bar). Holding the interact button on an item resets its despawn timer.

You can make a dropped item exclusive (only visible/pickable by one player) using dropped->set_exclusive(player).