Item Definitions & Fragments

UCrimsonInventoryItemDefinition is a Const, Abstract, Blueprintable UObject data asset. It holds Fragments (definition-level data) and StateFragments (per-instance mutable state templates).

cpp

UCLASS(Blueprintable, Const, Abstract)
class UCrimsonInventoryItemDefinition : public UObject
{
    UPROPERTY(EditDefaultsOnly, BlueprintReadOnly, Category = Display)
    FText DisplayName;

    UPROPERTY(EditDefaultsOnly, BlueprintReadOnly, Category = State, Instanced)
    TArray<TObjectPtr<UCrimsonInventoryItemFragment>> Fragments;

    UPROPERTY(EditDefaultsOnly, BlueprintReadOnly, Category = State, Instanced)
    TArray<TObjectPtr<UCrimsonInventoryStateFragment>> StateFragments;

    UPROPERTY(EditAnywhere, BlueprintReadWrite, Category = Item, meta = (AssetRegistrySearchable))
    FGameplayTag ItemType;
};

Built-in item fragments

Class	Display Name	Key properties
`UCrimsonInventoryItemFragment_Data`	Inventory Data	`bUnique`, `bStackable`, `MaxStackSize`
`UCrimsonInventoryItemFragment_Footprint`	Inventory Footprint	`Dimensions` (FIntPoint, for grid), `Weight` (float, for weight constraint), `SlotCost` (int, for multi-slot flat items), `bAllowRotation`
`UCrimsonInventoryItemFragment_Visuals`	Item Visuals	`ItemIcon`, `SlotWidgetClass`, `PickupActorClass`, `PickupMesh`
`UCrimsonInventoryItemFragment_Constraint`	Inventory Constraints	`ConstraintsToCheck` - instanced constraints evaluated alongside the component stack
`UCrimsonInventoryItemFragment_GrantCurrency`	Grant Currency	Currency type and amount granted on pickup (item is consumed)

cpp

UCLASS(Blueprintable, DisplayName = "Inventory Footprint")
class UCrimsonInventoryItemFragment_Footprint : public UCrimsonInventoryItemFragment
{
    /** W x H in cells (grid layouts). */
    UPROPERTY(EditAnywhere, BlueprintReadOnly, meta = (ClampMin = "1"))
    FIntPoint Dimensions = FIntPoint(1, 1);

    /** Mass / encumbrance per single unit (weight layouts + float-tag weight constraint). */
    UPROPERTY(EditAnywhere, BlueprintReadOnly, meta = (ClampMin = "0.0"))
    float Weight = 0.f;

    /** Slots this item consumes per stack in a flat-slot layout. */
    UPROPERTY(EditAnywhere, BlueprintReadOnly, meta = (ClampMin = "1"))
    int32 SlotCost = 1;

    /** Whether grid layouts may rotate this item to fit. */
    UPROPERTY(EditAnywhere, BlueprintReadOnly)
    bool bAllowRotation = false;
};

Sensible defaults

Items without a Footprint fragment behave as 1x1, weight 0, 1-slot. You only need the fragment when an item is genuinely larger, heavier, or non-default.

State fragments (per-instance replicated mutable state)

Class	Purpose	Key API
`UCrimsonInventoryStateFragment_Durability`	Tracks current/max durability for equipment	`ApplyDurabilityChange(float)`, `GetDurabilityPercentage()`, `IsBroken()`
`UCrimsonInventoryStateFragment_Lifetime`	Tracks elapsed time for time-limited items	Timer-driven countdown; override in BP to implement expiry