Interaction, Inventory and Using Items

Interaction

Interaction is performed using the E key. When the Character is overlapping with an Item, they can press E to Interact with it.

Note: Item is a C++ class derived from AActor. It is used as a base class for all items that can be interacted with by the Character. The Shield, Weapon, FoodItem classes are all children of Item and override its functions.

For now, Interact functionality is the same for all Items. Interaction with any Item would Destroy() it and add a copy into the Character’s Inventory.

This functionality was done by making a class UInteractInterface deriving from UE4’s Interface C++ class.
This InteractInterface has a virtual function Interact(AActor* Interacter) that gets overriden in Item like so:

Interact()

void AItem::Interact(AActor* Interacter)
{
	// Cast Interacter to Main
	AMain* Main = Cast<AMain>(Interacter);

	if (Main)
	{
		Main->ResetIdleTimer();

		//Add values to a SlotStructure Object
		FSlotStructure SlotStructure;
		SlotStructure.ItemStructure = ItemStructure;
		SlotStructure.Quantity = 1;

		// Add the object to the Inventory
		bool Success = Main->Inventory->AddToInventory(SlotStructure);

		if (Success)Destroy();
	}
}

Inventory menu

The Inventory menu is toggled by the Tab key and shows a grid of the Items that the Character has in its Inventory.

• Inventory menu

Each Item slot on the grid shows a thumbnail image and quantity. When the player hovers the mouse pointer over a slot, an Item tooltip appears next to the pointer to show the Item’s name, description and an Use text (for example: “Click to Eat.”).

Clicking on the Item slot calls a virtual function UseItem() declared in Item.

If the Item was labeled as Consumable, it would be spawned with scale (0.0, 0.0, 0.0) and if labeled as Equippable, (1.0, 1.0, 1.0). A Consumable Item’s Quantity would also be decremented after calling its UseItem() function.

Following is UseItem() defined in class Weapon. Using the Item removes the currently Equipped Weapon and attaches itself to the required socket.

UseItem()

bool AWeapon::UseItem(AMain* Main)
{
	// Call the base function
	Super::UseItem(Main);

	// If this is a Two-Handed Weapon, remove the equipped Shield, if any
	if (bIsTwoHanded)
	{
		if (Main->EquippedShield)
		{
			Main->EquippedShield->Destroy();
			Main->SetEquippedShield(nullptr);
		}
	}

	Main->SetEquippedWeapon(this);

	// Disable collision of the CollisionVolume
	CollisionVolume->SetCollisionEnabled(ECollisionEnabled::NoCollision);
	CollisionVolume->SetCollisionResponseToAllChannels(ECR_Ignore);

	// Set Weapon Instigator
	SetInstigator(Main->GetController());

	SkeletalMesh->SetCollisionResponseToChannel(ECC_Camera, ECR_Ignore);
	SkeletalMesh->SetCollisionResponseToChannel(ECC_Pawn, ECR_Ignore);

	SkeletalMesh->SetSimulatePhysics(false);

	bShouldRotate = false;

	if (!bWeaponParticles)
	{
		IdleParticlesComponent->Deactivate();
	}

	// Attach Weapon to Sheath Socket.
	Main->TimedSheathe();

	// Set bIsWeaponDrawn as false as the Weapon is sheathed.
	Main->bIsWeaponDrawn = false;

	// If in Combat Mode, draw the weapon.
	if (Main->bInCombatMode)
	{
		Main->DrawWeapon();
	}

	return true;
}

You can view the code of the project here!

In Action

• Adding and Using Item: Herb

• Adding and Using Item: Bread