Inventory Screens

Documentation Unreal Engine Player Combat Inventory UI

Each ready inventory style ships its own inventory screen, opened with I or a tap of View. Copy one and restyle it, or build your own on the checks and requests the shipped screens use.

Set it up

3 minutes

1
Use the open world list
Open BP_UPC_Character, select InventoryComponent, and set Config to InventoryConfig_UPC_OpenWorldList from Demo/Items/Inventory.
2
Take the chest's loot
Press Play in LVL_UPC_Demo, walk down the hallway to the loot chest and press F. Its three potions, the ring and the necklace move into your satchel.
3
Drink a potion
Press I, or tap View. Click Consumables in the category column, or move to it and press A. Point at the potions and click them, press E, or press A: the stack drops to two, and Health rises when it is below full (UPC.Debug.Vitals 1 shows it). Press I to close.

Keys

To	Keyboard and mouse	Gamepad
Open your inventory	I	Tap View (holding it a second respawns)
Close it	I or Escape	View or B
Open it at a stash box or a loot chest	E	A

On the open world list:

To	Keyboard and mouse	Gamepad
Open a category	Click it, or Enter or Right on it	A, or Right
Highlight an item; its card follows	Point at it, or Up and Down	D-pad or stick
Run its main action; at a chest or the stash, Take or Store	Click it, right click it, or E	A
Pick it for Combine	C, or click the Combine prompt	Right trigger
Drop it; at a chest, take everything	R	X
Put it on a belt slot (a quick-use slot), when the config has one	F, or 1 to 4 for that slot	Y
Step through the categories of the panel you are in		LB and RB
Cross to the chest or stash panel and back	Arrows	D-pad
Back to the categories, then close	Left, or Escape	Left, or B

On the survival grid and party RPG screens:

To	Keyboard and mouse	Gamepad
Select an item and show its actions	Click it	D-pad
Move an item	Drag it	A to pick it up, A where it goes
Put a picked-up item back	Escape	B
Run its main action; with a chest open, store your own item	Right click it
Focus its actions	X	X
Turn a picked-up item in a grid	R	Y
Move between panels	Q and E	LB and RB
Put the picked-up or selected item on a belt slot	1 to 4

A prompt or button grays out while it cannot run. An item dragged out of the panel drops to the ground. The open world list pauses a solo game; disconnect Pause For Screen in the screens component's Open Inventory to keep it running.

The three screens

BPC_UPC_InventoryScreens, on the player controller, opens the screen its Inventory Screen Classes names for the character's config; a config with no row gets the Fallback Inventory Screen, the open world list, and a row naming no screen opens none, as for the demo player's InventoryConfig_UPC_Simple.

Config	Screen	Shows
`InventoryConfig_UPC_OpenWorldList`, unlisted configs, no config	`WBP_UPC_InventoryScreen_OpenWorldList`	Category column, one sorted list, the highlighted item's card with prompts, weight bar
`InventoryConfig_UPC_SurvivalGrid`	`WBP_UPC_InventoryScreen_SurvivalGrid`	Grid case of turning items, open pouches' cells under it, key items, Hands doll, Sort button
`InventoryConfig_UPC_PartyRPG`	`WBP_UPC_InventoryScreen_PartyRPG`	Backpack with Sort button, one pouch's slots at a time, paper doll, belt row, weight bar

Each screen also shows the belt when the config has one, and a stash's or chest's items beside yours. Survival Grid, Party RPG and Open World List cover each config.

Item actions

An item's actions follow its fragments (Items).

Action	Works on	Sends
Equip, Unequip	An item with an Equippable fragment	Request Equip Item, Request Unequip Item
Consume	Demo `BP_UPC_ItemFragment_UseEffect` (potion heals 40, mixed herb 50)	Request Use Item, answered by `GA_UPC_UseItem`
Combine	An item a carried item combines with	Request Combine
Drop	An item with a World Item fragment	`UPC.Event.DropItem`, answered by `GA_UPC_DropFromScreen`
Add to belt	An item a press of the slot would draw or use	Request Assign Slot
Split (grid, party RPG)	A stack: half moves to the first free place of its container	Request Move
Take, Store (chest or stash box)	An item in the chest or stash, or yours while one is open	Request Transfer at a chest, Request Move at the stash

The main action is the first that applies: Take, Store, Unequip, Equip, Consume. Consume and Drop need GA_UPC_UseItem and GA_UPC_DropFromScreen, which the demo's AbilitySet_UPC_Default grants; add both to your character's Starting Ability Set (Input).

Combine

Pick Combine on an item (C or the right trigger on the open world list, the item's actions elsewhere), then pick the other item with its main action. An item in hand counts, so poison coats the sword in hand. A line with a Cancel button names the picked item; Cancel, Back, a right click, closing the screen or a count change lets it go. On the grid and party screens, dropping one item on another also combines them. Combines covers recipes.

Open it at a box or a chest

On the actor's UPC Interactable, an Options entry with Option Id OpenInventory opens the screen as its payload starts, with the actor's UPC World Inventory beside your bag when it has one. An option with no payload opens nothing, so give it one that ends at once. Closing the screen brings the prompt back.

Interaction Option

▾Option

Option Id

Payload Spec

Delay Seconds

Stash: BP_UPC_StorageBox gives the character its storage container's Access Tag while it stands in the box's zone, so any inventory screen opened there shows the stash beside your items. A project that wants the stash only through the box's Open option grants the Access Tag when that option runs instead of on entering the zone. Take and Store move as many units as fit, to the place where most fit; a drag moves them where you drop them.
Loot chest: BP_UPC_LootChest's E opens the screen and F takes everything without one (Loot Chests).

An item in the stash or chest also takes Equip, Add to belt and a drag onto the belt or paper doll: one step brings it into your inventory and hand or belt, under a Take's checks (reach, access, weight). A refusal shows on the message line (Too Heavy, Full). On the survival grid an item on the belt or in hand takes no cell.

Copy a screen into your game

The screens are standard-UMG Widget Blueprints in Demo/UI/Widgets/Inventory.

Duplicate the screen and BPC_UPC_InventoryScreens into your folder, and put the component copy on your player controller in place of the demo's. It toggles the screen on IA_UPC_Inventory (mapped to I and a tap of View in the demo's IMC_UPC_Default); a controller of your own needs a mapping context with that action.
Register your config: add a row to Inventory Screen Classes, a map in the component copy's Class Defaults (not on the config), pairing your config with your screen; without one the copy opens the fallback.

Details

Class Defaults

Inventory Screens

Inventory Screen Classes

3 Map elements

InventoryConfig_UPC_OpenWorldList

WBP_UPC_InventoryScreen_OpenWorldList

InventoryConfig_UPC_SurvivalGrid

WBP_UPC_InventoryScreen_SurvivalGrid

InventoryConfig_UPC_PartyRPG

WBP_UPC_InventoryScreen_PartyRPG

Fallback Inventory Screen

WBP_UPC_InventoryScreen_OpenWorldList

Inventory Screen Context

IMC_UPC_InventoryScreen

Inventory Screen Context Priority

100

Open Inventory Option Id

OpenInventory

The screen each inventory config opens. A config with no row, and an inventory with no config, open the fallback.

Restyle the copy in the Widget Blueprint editor. Most games change these:

Setting	On	Holds
Category Rows	Open world list	Each category's label and item kinds; Other Kinds for what no row names, Belt Only for the belt's items
Places	`WBP_UPC_PaperDoll`	Each body place, its label and tile position
Refusal Words	Message line	Words per refusal reason; a reason with no row shows the last part of its tag

WBP_UPC_ListPanel draws one container as a category column beside a sorted list; place one per inventory shown. Mirrored puts the column on the right, Neighbor lets the arrows cross to the next panel.

A copy keeps using the Common blocks (tiles, views, panels, paper doll, message line) and the carry flow in BFL_UPC_InventoryScreens (pick up, put down or back, send to belt), so keep the demo in your project.

Rearrange freely. The screen finds each piece by its variable, so move or wrap any panel. The weight bar, belt panel, hint bar and item details can go; the list, grid and slot views, message line and actions are its core.

Restyle everything from one asset

Change Colors, Fonts, Surfaces (including Extra Cells, the frame around a pouch's cells) and Sizes in Demo/UI/Theme/UITheme_UPC_Default; screens (copies too), HUD, interaction prompts and showcase key hints follow. To theme a widget you add, give it a row in the Theme Roles map in its containing Widget Blueprint's Class Defaults: the widget's name and a role, such as InfoBox with Panel for a Border named InfoBox. Rename the key with the widget, or that part keeps its own look and the Output Log names the old key.

Build your own screen

A screen of your own reads the inventory on the player's machine and sends requests; only the server changes it:

Draw each container Get Containers lists, from Get Items in Container (it leaves out an item that gave up its place while on the belt or in hand), on the pawn's UPC Inventory.
Bind On Layout Changed to redraw the container it names, and On Capacity Changed to redraw one that grew, shrank, opened or closed.
Act through a request: ask its check (table below), then send it. A Take or Store button picks no place, so it first asks a finder where the most units fit, then sends the finder's Out Destination:

Button	Ask	Then send
Take from a chest, or Store in one	Find Transfer Destination, with the chest's World Inventory	Request Transfer
Store in the stash	Find Move Destination, with the stash's container	Request Move
Take out of the stash	Find Add Destination	Request Move

The server makes the change; On Layout Changed redraws it.

Read the inventory

The smallest read side prints a container on every change:

BP_UPC_Character · print a container whenever it changes

Container

Target

Container

Return Value

Array

Loop Body

Completed

Array Element

Array Index

Target

Return Value

Target

Display Name

Target

Instance

Return Value

Format{Name} x{Count}

Name

Count

Result

In Text

AdvancedEvery read node and event

Node	Answers
Get Containers	Every container in the order adds fill them, open bags included.
Get Container Definition	Display Name, Icon, Layout.
Get Container Size	Slots by 1, columns by rows, or 0 by 0 for a list.
Get Items in Container	Items in place order.
Get Items in Sort Order	Items in the order Request Sort would lay them out, moving nothing.
Get Item At	The item in a slot (a grid cell included) or at a list position.
Get Item Placement	Container, Position (-1 for no place) and Rotated.
Get Item Cells, Get Position Of Cell	An item's top-left cell and size as it lies; the Position a cell stands for.
Get Item Stack Count	The count to print.
Get Weight, Get Effective Limit	The load; the Weight Limit rule's limit with its bonus.
Get Item Footprint	Grid size, for a drag picture or tile.
Is Held By	Whether the belt or a hand holds the item.

Event	Fires
On Layout Changed	Once per changed container, after the change settles.
On Capacity Changed	A container's size changes (capacity bonus, bag opening or closing).
On Carry Changed	A change that can move the load or a rule's answer: reread Get Weight.
On Item Count Changed	With an item and the units the character carries.
On Combined	As a combine's units land, once per group landing together.

Ask before you send

The server runs each request's check too; ask it first so a button grays out.

Before you send	Ask
Request Move	Can Place
Request Transfer (chest)	Can Transfer
Request Assign Slot (belt)	Can Assign Slot
Request Equip Item (equipment manager)	Can Equip Item
Request Unequip Item	Can Unequip Item
Request Use Item	Is Item Carried And In Reach
Request Combine	Can Combine (UPC Inventory Statics)
A Drop button	Can Item Leave
A bank panel's "go to the bank" state	Is Container In Reach

AdvancedMove, sort, Take and Store

Can Place answers what moving Count units to a Destination would do, with Out Units the units that move:

Answer	The drop
Place	Moves into a free place; part of a stack splits off there.
Merge	Joins a stack of the same item, as many units as fit (5 of 15).
Swap	Trades places with the one item there.
Combine	Runs a Combine Set recipe or combine (Combines).
Into Bag	Goes inside the open bag there (Bags and Banks).
Refused	Moves nothing; Out Reason says why.

Request Move moves the units as Can Place answered. A held item moves where it is dropped: Request Move lets go of it first (belt clear, or put-away for an item in hand alone), then places it, and refuses when letting go leaves it no place. A screen's drop onto a place sends the move first, then clears the belt slot or sends Unequip (sent first, an Unequip can start a timed put-away that refuses the move). Where Belt Space or Equipped Space frees an item's place, as on the survival grid, one request takes the whole stack off the belt or out of the hand. Find First Fit answers the first free place a new stack would take, for a "move to" button.

Request Sort tidies one container: same-item stacks join, then items follow the config's Sort Order, then name, then larger stacks (a grid places larger items first). A container it cannot lay out whole stays as it was. Call both requests on the player's machine. A finder prefers a stack with room over a free place, and answers a refusal with its reason when nothing fits.

AdvancedWhy a move is refused

Each reason is a tag under UPC.Inventory.Refused, worded for the player by the demo's Refusal Words:

Reason	Means
`Full`	No free place, or the stack to join is full.
`TooHeavy`, `CategoryFull`, `NotAdmitted`	A Weight Limit, Category Limit or Item Filter refused it.
`NoAccess`	Missing a container's or chest's Access Tag.
`OutOfReach`	A chest beyond its Access Radius.
`OutOfBounds`	A place outside the container, a disallowed turn, a container the inventory lacks, or a bag's own container.
`Occupied`	Items there the moved item can neither join nor swap with.
`Held`	A stack on the belt or in hand would leave what the character carries, or empty into another stack. A finder answers Held only when more would land once the belt or hand let go; a full chest answers Full.
`CapacityInUse`	An item giving extra slots or rows leaves while items lie there (the demo says Empty the extra slots first).
`Split`	Part of a stack whose units carry their own state, such as charges; it moves whole.
`BagNotEmpty`	A bag holding items would go inside another bag.
`NoCombine`	Request Combine named two items no Combine Set takes.
`NotEnough`	A recipe needs more units than the stack holds.
`Locked`	Missing the recipe's Required Tags.

AdvancedEquip from the inventory

Request	Does
Request Equip Item	Draws or puts on an owned item, putting away whatever holds its places. Place names the body place; empty takes the places a press would.
Request Unequip Item	Puts a drawn or worn item away.
Request Cancel Sequence	Stops the running change while a pending step names the item, as closing a screen does.

The config's Equip At Once and Put Away At Once pick instant landing or Draw Timing and Stow Timing, each with optional start and land sounds and Cancel on Move (Containers and Rules). A belt press is not timed this way.

Can Equip Item wants the item equippable, out of hand and takeable (Can Take To Hold: carried and in reach, or in reach in the stash or a chest with a carried container that takes the whole stack), the equipment action's Plan Draw to agree, a place to return to under Equipped Space, and no running change or action holding equipment back. Can Unequip Item wants it in hand with a place to go back to, and Plan Stow to agree (Equipment covers both plans).

A progress bar listens to the equipment manager's On Equip Step Started (the step's Source Item and Timing from Start Time) and On Equip Sequence Ended (a stop's Reason under UPC.Equipment.Cancelled: Moved, Asked, Blocked, Item Left or Interrupted; steps that landed stay), and reads Get Playing Step when it opens partway through.

A paper doll lists its places, asks Get Instance In Place for each (skipping the item with Is Default Item true) and redraws on On Drawn State Changed. A dragged item lights a place where Can Equip Item with that Place says yes, and the drop sends Request Equip Item with it. Equipment covers worn gear and places.

AdvancedThe belt from a screen

Request	Does
Request Assign Slot	Puts an item in a belt slot, as a belt drop does. Empty clears it; an item from another slot trades places; an inventory item takes the slot from the item there. An item in hand is let go at once, with no animation.
Can Assign Slot	Whether it would land: Filter, copy limit, reach, and a place for the item the belt lets go. A stash or chest item passes when Can Take To Hold does.

Find Quick Bar For Pawn finds a belt, Get Slot Of Item an item's slot, and Equip Item If Free draws an item from code at once when it is undrawn, carried, in reach and its places are free.

The demo screens and HUD draw the belt with Get Belt Layout: a diamond for four slots that each name an item kind, a row otherwise, None (hiding every belt part) for no slots. They offer only items Can Put On Belt allows (Equippable or Use Effect fragment). Both live in BFL_UPC_InventoryScreens; Quick Bar owns the belt's rules.

AdvancedUse, drop and move sounds from a screen

Request Use Item uses an item, as a belt slot does (Inventory). A Drop button asks Can Item Leave (false out of reach; a bag leaves with its items), then sends UPC.Event.DropItem, answered by a UPC Drop Ability with Item Selection From Event and an Ability Trigger on that event, as GA_UPC_DropFromScreen (Pickups, Drops and Holders).

Get Inventory Move Sound, on the equipment manager, gives the pick-up or put-down sound, or None when the item's own draw or put-away sound plays.

Debug it

Log LogUPCInventory Verbose names refused inventory requests, Log LogUPCEquipment Verbose equipment ones.

AdvancedWhat the screens show

A tile shows the icon, count (×4), belt slot in a key-cap badge, an equipped mark, and a holder's load (6/15 on a magazine). A timed equip or combine draws a progress bar along it; closing the screen stops it.
A dragged item stays at the spot you pressed. On the survival grid its picture covers its cells and the case lights them. A line names the put-down (Put it here, Swap places, Combine) or, in Refusal Words, why not. Let go inside the panel away from any tile, it stays put.
The paper doll shows head, neck, shoulders, chest, hands, feet, both hands and both rings. A drop on a place puts back what held it (a spare sword on the shield's place swaps the two); a worn tile dragged off comes off. A place lights green where Can Equip Item takes the item, red where not; the off hand grays out while a two-handed weapon holds both hands.
The open world list shows icon, name, count, weight and gold value, and refuses a reorder (it keeps its sort order).
An open screen stops move, look and combat input; the HUD stays and interaction prompts hide. The screens component reads Pauses Game from Get Screen Rules on opening; while paused, the screen's keys keep working and an equipped item shows at once.
The Inter and Cinzel licenses ship beside their fonts in Demo/UI/Fonts.

MultiplayerWhat runs where

A screen opens only for its controller's local player and reads that player's inventory.
In split screen each screen sits on its player's part (scaled down when too wide) and only the first player has the mouse. Input mode is Game and UI, never UI Only, which would freeze the other player.
Every request is a reliable server call; the server runs the same check and drops a refusal silently. Nothing is predicted, so a change (or another player's chest take) arrives about a round trip later.
Request Use Item and a belt use both send UPC.Event.UseItem, so one Server Only ability answers both. A timed equip or combine plays on the player's machine about half a round trip after the server and stops with the server's reason.

C++C++

UUPCInventoryComponent::CanPlace and RequestMove share one check, answering EUPCPlaceResult; GetItemsInSortOrder and RequestSort share one comparator.
RequestUseItem refuses a world inventory, asks IsItemCarriedAndInReach and sends UPC.Event.UseItem, the event UUPCQuickBarComponent sends for a slot holding an item that is not equippable.
RequestEquipItem(Item, Place) and RequestUnequipItem(Item) ask CanEquipItem or CanUnequipItem, then run DrawWithReach and StowWithReach, or DrawAtOnce and StowAtOnce under the config's bEquipAtOnce and bPutAwayAtOnce. The equipment action's PlanDraw and PlanStow decide what a draw plays.
RequestCombine(Item, Target) runs CanCombine, then one equipment change through StartCombine; bCombineAtOnce lands every unit in that call.
FUPCItemActionTiming holds Seconds, the two sounds and Cancel on Move, on the config and on the Equippable fragment.
The screens add no C++ widget class: each derives from User Widget, apart from the hint bar and its row, which derive from UUPCInputHintListWidget and UUPCInputHintWidget.

AdvancedTroubleshooting

I opens no screen. The player controller carries no BPC_UPC_InventoryScreens, or its mapping context lacks IA_UPC_Inventory.
I opens the open world list under another style. Inventory Screen Classes has no row for the character's config.
Consume is missing or does nothing. The item has no Use Effect fragment, the ability set lacks GA_UPC_UseItem, or your own use ability is not Server Only.
The storage panel never shows at a box. The box's Access Tag differs from the Access Tag of the config's storage container.
Combine does nothing. No recipe or combine in the config's Combine Sets takes the pair (Combines).