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03 — Authoring Items

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How to create an item type, a full reference of its fields, and ready recipes for common items.

Creating the asset

Content Browser → right-click → Miscellaneous → Data Asset → ISItemDefinition.

Location — anywhere in your content. The plugin discovers items through the Asset Registry by class, so the folder structure is yours, and moving assets breaks nothing.

One caveat about the name. The asset name is the item's stable identity: it's what goes into saves and into console commands. Renaming the asset after release invalidates references in other people's save files. DisplayName, on the other hand, can be changed at any time — nothing references it.

Field reference

Presentation

Field Description
DisplayName The name the player sees. Localised like any FText.
Description Longer text for a tooltip or a details panel.
Icon Icon for the UI. A soft reference — see below.
PickupMesh Mesh for an item lying on the ground. Also a soft reference.

Why the icon is a soft reference. Owning an item doesn't pull the texture into memory. Your UI decides when to load it (Blueprint: Async Load Asset; C++: StreamableManager). Because of this, a thousand item types don't drag a thousand textures into the memory of a dedicated server that doesn't need them at all.

Classification

Field Description
ItemTags What the item is: Item.Type.Weapon.Melee, Item.Rarity.Rare, Item.Property.Tradeable.

These tags are read by inventory filters, slot restrictions and queries. Typically an item has one type tag, one rarity tag and any number of property tags.

Matching is hierarchical: an item tagged Item.Type.Weapon.Melee also answers a query for Item.Type.Weapon.

Capabilities

Field Description
Fragments What the item can do. This is where item design happens.

Order matters only for OnUsed — fragments run top to bottom.

Details on each fragment in 04 — Fragments.

Derived values (read-only)

These functions are computed from the fragments and are convenient to call from the UI:

Function What it returns
GetMaxStackSize() how many copies fit in a slot; 1 without a Stackable fragment
GetUnitWeight() weight of one copy; 0 without a Weight fragment
IsUsable() whether a "Use" button makes sense

Recipes

Ready combinations for the most typical items. Copy the closest one and change the values.

Health Potion

DA_HealthPotion
├── DisplayName: "Health Potion"
├── ItemTags: Item.Type.Consumable
└── Fragments:
    ├── Stackable      → MaxStackSize: 10
    └── Consumable     → ConsumeAmount: 1
                         EffectTags: Effect.Heal

The healing itself is yours to implement — the plugin only reports the effect tags. How to wire it up is shown in 04 — Fragments.

Sword

DA_IronSword
├── DisplayName: "Iron Sword"
├── ItemTags: Item.Type.Weapon.Melee, Item.Rarity.Common
└── Fragments:
    ├── Equippable     → EquipmentSlot: Equipment.Slot.Weapon.Main
    │                    EquippedActorClass: BP_SwordActor
    │                    AttachSocketName: hand_rSocket
    │                    GrantedStats: { Item.Stat.Damage: 12 }
    └── Durability     → MaxDurability: 100
                         DurabilityPerUse: 1

Doesn't stack (no Stackable), has individual durability, appears in the character's hand.

Crafting material

DA_CopperOre
├── DisplayName: "Copper Ore"
├── ItemTags: Item.Type.Material
└── Fragments:
    ├── Stackable      → MaxStackSize: 99
    └── Weight         → UnitWeight: 0.5

Ammo for a special slot

DA_Arrow
├── DisplayName: "Arrow"
├── ItemTags: Item.Type.Ammo
└── Fragments:
    └── Stackable      → MaxStackSize: 50

To make arrows land only in the first backpack slots, configure SlotRestrictions on the component — see 05 — Inventory Operations.

Quest item

DA_SealedLetter
├── DisplayName: "Sealed Letter"
├── ItemTags: Item.Type.Quest, Item.Property.QuestItem
└── Fragments: (empty)

No fragments: takes one slot, doesn't stack, does nothing when used. The Item.Property.QuestItem tag lets a shop block its sale via BlockedItemTags.

Torch with fuel

DA_Torch
├── DisplayName: "Torch"
├── ItemTags: Item.Type.Tool
└── Fragments:
    ├── Equippable     → EquipmentSlot: Equipment.Slot.Weapon.Offhand
    │                    EquippedActorClass: BP_TorchActor
    └── Consumable     → MaxCharges: 100
                         bDestroyWhenChargesSpent: true

Charges mode: the item stays in the slot spending charges, and disappears when the fuel runs out.

Item validation

The plugin validates assets automatically — in the editor on save, and at world startup in dev builds. It reports:

  • an empty DisplayName;
  • an empty entry in Fragments;
  • two fragments of the same class (the second silently overrides the first);
  • an Equippable with no slot set;
  • a Stackable with MaxStackSize < 2;
  • a Durability with MaxDurability <= 0 (every copy would start broken).

Turn it off at Project Settings → Game → Inventory System → Validate Items On Startup.

To check everything by hand, run the DemoInvItems command — it lists every item type in the project.

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