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Inventory Components

Overview

The Inventory system is built around UMIPBaseInventoryManagerComponent (IMC), which holds a replicated list of item entries, slot counts, and sorting state. UMIPPlayerServerIMC extends it for the player (equip/unequip, consume, move, swap). UMIPStoragesManagerComponent and storage IMCs (UMIPStorageIMC, UMIPDynamicStorageIMC, UMIPNPCStorageIMC) manage multiple inventories (storages) and moving items between them. UMIPItemSelectionComponent handles UI-driven item selection (e.g. repair one, enhance).

Key traits:

  • Server-authoritative: Add/remove/move/swap are server RPCs or server-only; replication keeps clients in sync.
  • Save: Items and slot state are persisted via the save system; saveable component integration for load order.
  • Slots: Max size, unlocked size, temp unlocked, used slots; expansion and slot checks for add/move.

All paths below are relative to Plugins/ModularInventoryPlus/Source/ModularInventoryPlus/.

Key Classes & Files

Class File
UMIPBaseInventoryManagerComponent Public/Inventory/MIPBaseInventoryManagerComponent.h
UMIPPlayerServerIMC Public/Inventory/PlayerInventory/MIPPlayerServerIMC.h
UMIPStoragesManagerComponent Public/Inventory/Storage/MIPStoragesManagerComponent.h
UMIPStorageIMC Public/Inventory/Storage/MIPStorageIMC.h
UMIPDynamicStorageIMC Public/Inventory/Storage/MIPDynamicStorageIMC.h
UMIPNPCStorageIMC Public/Inventory/Storage/MIPNPCStorageIMC.h
UMIPItemSelectionComponent Public/Inventory/ItemSelection/MIPItemSelectionComponent.h
UMIPAdvancedChatItemLinkerComponent (inventory-related; see plugin Public/Inventory)

Component Hierarchy

UMIPBasePlayerControllerComponent
└── UMIPBaseInventoryManagerComponent   (base IMC; implements IAbilitySystemInterface)
    └── UMIPPlayerServerIMC             (player inventory: equip, consume, swap, move)
    └── UMIPStorageIMC                  (generic storage)
        ├── UMIPDynamicStorageIMC        (tag-based dynamic storage)
        └── UMIPNPCStorageIMC            (NPC-bound storage)

UMIPBaseSaveableComponent
└── UMIPStoragesManagerComponent        (holds StorageIMCs + DynamicStorageIMCs, active storage, move-to-storage)

UMIPClientPlayerControllerComponent
└── UMIPItemSelectionComponent          (StartItemSelection / StopItemSelection, hover callbacks)

UMIPBaseInventoryManagerComponent

  • Replication: FMIPItemList UnsortedInventoryList, UsedItemSlots, UniqueInventoryTag (ReplicatedUsing).
  • Slots: MaxInventorySize, UnlockedInventorySize, TempUnlockedSlotsSize, SlotsPerRow. Helpers: GetTotalUnlockedSlotsCount(), IsAtMaxSlots(), CheckHasEnoughSlots, CheckHasEnoughSlotForItem, GetRequiredItemSlots, IsSlotIndexUnlocked. Unlock is driven by UMIPControllerCommonSaveableObjectsComponent (permanent) or temp internal.
  • Items: GetItemEntriesConst(), GetItemEntryAtIndexConst, HasEnoughItem, HasItemTag, GetItemIndexByTag, GetItemIndexByUniqueId, GetItemCountByTag, GetFreeItemIndex, IsIndexFree. Add: AddItemByTag / AddItemByTagNoNotification. Remove: RemoveItem_ServerOnly, RemoveItemByTag_ServerOnly, RemoveItemByUniqueId_ServerOnly. Load: LoadItem, OnItemFullyLoaded. Create: CreateTempItemEntry, CreateTempItemEntryWithAssetId, CreateTempItemEntryWithDynamicPieces.
  • Move: MoveItemToAnotherInventory(InTargetIMC, ...), CheckThisInventoryCanMoveForItem.
  • Swap: SwapItemIndexes, ServerSwapIndexes.
  • Currency: RemoveCurrency, HasEnoughCurrency (delegate to UMIPCurrencyComponent).
  • Sorting: SortedItemsMapping, GetItemEntryAtSortedIndex, GetRealItemIndex, GetSortedItemIndex, bAutoArrange, OnAutoArrangeStateChanged, SortAndBroadcast, ClientItemEntriesSortedDelegate.
  • Delegates: ItemEntryChangedDelegate, ClientItemEntriesSortedDelegate, OnItemSlotsCountChangedDelegate.
  • Save: GetSaveID(), MarkPieceDirty, MarkItemEntryDirty / K2_MarkItemEntryAsDirty. Listens to OnAllLoadingCompleted and replication change.

UMIPPlayerServerIMC

  • Delegates: ItemEntryRemovedDelegate, OnItemEquippedDelegate, OnItemUnequippedDelegate, OnEquipmentMeshShowOrHideDelegate, ClientEquipmentEntryRemovedDelegate, ClientEquipmentEntryAddedDelegate, NotifyAddItemResultDelegate, ClientOnConsumeItemDelegate, ServerOnConsumedItemDelegate, ClientOnFailedToConsumeItem, EquipUnEquipSoundDelegate.
  • Struct: FMIPRemovedItemInfo (RemovedItemType, ItemPrimaryTag, ItemUniqueId, ItemIndex). Equip/unequip and mesh show/hide use the existing structs in the codebase.
  • Behavior: Extends base IMC with server RPCs for equip, unequip, consume, and client/server delegate flow for UI and gameplay.

UMIPStoragesManagerComponent

  • Attachment: Owned by actor that has saveable + storage responsibility (e.g. player).
  • Storage lists: StorageIMCs, DynamicStorageIMCs (by tag). FindStorageIMCByTag, GetCurrentActiveStorageIMC, GetCurrentActiveStorageTag, GetDynamicStorageIMCByTag, GetCurrentActiveDynamicStorageIMC. AddStorageIMC, AddUniqueStorageIMC.
  • Move: StartMoveItemToStorage(FromIndex, ToIndex, Amount), OnMoveItemFromStorage (callback with value + additional data).
  • Repurchase: GetRepurchaseStorageLastSoldSequence(Tag), IncrementRepurchaseStorageLastSoldSequence(Tag); RepurchaseStorageTagAndSequenceMap (SaveGame).
  • Delegates: StorageItemEntryChangedDelegate, OnDynamicInventoryItemEntryChangedDelegate. OnItemEntryChanged, OnDynamicInventoryItemEntryChanged forward to these.
  • Config: EndStorageInteractionTags – when interaction ends, active storage can be cleared or updated as needed.

UMIPStorageIMC / UMIPDynamicStorageIMC / UMIPNPCStorageIMC

  • UMIPStorageIMC: Base storage IMC; TryMoveItemToStorageOnServer, ServerMoveItemToInventory, ClientInitializeStorage.
  • UMIPDynamicStorageIMC: InitializeDynamicStorage(UniqueInventoryTag), RemoveFirstSoldItem; overrides OnItemEntryChanged, OnRep_UniqueInventoryTag; registers with manager in AddDynamicStorageIMCToManager.
  • UMIPNPCStorageIMC: Spawnable storage component for NPCs; overrides BeginPlay and OnItemEntryChanged.

UMIPItemSelectionComponent

  • Attachment: Client PlayerController (UMIPClientPlayerControllerComponent).
  • API: StartItemSelection(InItemSelectionTag), StopItemSelection(), OnItemHovered(InItemEntry), OnItemUnhovered(InItemEntry) (and selection result flow). Uses UMIPSettings → ItemSelectionMapping (tag → TSubclassOf<UMIPBaseItemSelectionChecker>). Cursor changes via UMIPCursorComponent::ChangeCursorWithName (disabled cursor during selection; default on stop).
  • Delegates: FOnItemSelection, FOnItemSelectionSelected (item selection tag + result struct). Used for repair-one, enhance, etc. via custom checkers (e.g. UMIPRepairOneItemSelectionChecker).

Integration

  • Save/Load: Inventory entries and slot counts are saved/loaded via server load component and saveable objects; IMC listens for OnAllLoadingCompleted.
  • Currency: Fee checks and removal go through UMIPCurrencyComponent referenced on the base IMC.
  • Equipment: See UMIPEquipmentGE and equipment components; equip/unequip delegates on UMIPPlayerServerIMC.
  • Action progress / level features: Level-based features (e.g. enhance, reforge) use UMIPBasePlayerLevelBasedFeatureComponent and may trigger inventory operations.