Pickups, Drops and Holders

A world item (BP_UPC_WorldItem) holds an item, a count and the item's state, such as durability.

It shows the Visuals Drop Mesh, else the Mesh, firing On Visuals Ready, and collides as one box that characters and the camera pass through. A dropped bag carries its contents (Get Bag Items).

A world item offers Pick Up on Interact (E in the demo), its prompt showing the item's Display Name and Icon (Interaction). Units top up stacks of the item; one carrying state becomes its own stack. Under an inventory config a pickup takes what fits and leaves the rest (Get Units That Fit says how many and why). On Pickup Taken fires on the server as the item goes; Try Pick Up hands it over from your Blueprint.

With no room, Pick Up stays on the prompt with the reason as its verb (No Room, Too Heavy, Can't Carry More, Can't Carry, Out of Reach) and a press does nothing; a rack's Take does the same.

Tick Swap When Full on the inventory config to swap instead: the prompt reads Swap ("Swap Sword for Shield") and a press puts the item in the way down where the drop key would, then takes the new one. The item in the way is one in hand or on a belt slot that takes the new item, one of the same kind first, so a second sword replaces the sword put away on the belt and never the shield in hand. It swaps only when that item has a World Item fragment and putting it down makes room for the whole new stack, and never puts a stack down for more of the same item; otherwise the prompt keeps its reason. At a rack the item put down goes onto the emptied place when it fits. The demo's InventoryConfig_UPC_SingleItem (one slot, Swap When Full) shows it (One Item at a Time).

With no Pickup Presentation on the character's UPC Interactor, a pickup takes the item at once. Give it one for a reach: a Montage, and a Stand Off Distance, how far from the item the character stands.

The montage carries two notifies. A UPC Approach Window spanning the walk, with Approach Target Name Pickup, moves the character to the spot; without it Stand Off Distance moves nothing. A one-frame UPC Gameplay Event with Event Tag UPC.Event.Interaction.Commit where the hand closes takes the item; without it the item goes at the end. An item lifted differently, such as a crate, ticks Override Pickup Presentation on its World Item fragment for its own reach; one with no montage is taken at once.

An item with a World Item fragment can leave the hand and become a world item.

A character's ability set grants the plugin's drop ability with an Input Tag (UPC.Input.Drop) and an Input Action (Input). To change what a press drops, grant a Blueprint child of UPCDropAbility instead:

Override Can Drop to forbid a drop (a quest item) and Resolve Drop Transform for a throw; On Item Dropped fires on the server with the new world item. An item in a container out of reach stays; a bag drops with its contents, except items the belt or a hand holds.

Two server nodes drop without the ability and refuse items with no World Item fragment. Drop Equipment takes one unit of a drawn item off a character, as a disarm does, landing as its fragment says. Drop Item Instance lays units of an owned item at a transform you pass, resting under Physics Mode Force Disabled.

A UPC Item Holder holds items in named places such as a rack's pegs: a filled place offers Take, an empty one Put Back when the character carries an item the place accepts that has a World Item fragment. Put Back takes the sword in hand first, then another drawn item, then any other accepted carried item.

UPC.Debug.Interaction 1 shows what each character looks at and offers. Log LogUPCInteraction Verbose reports a drop refused for a missing World Item fragment or a playing reach.