UE4 C++ Multiple widgets created for the same actor in UI - c++

Question

I am trying to set up a system that displays the ground loot near the player (i.e., actors that are overlapping the player's UBoxComponent). This needs to change as and when the player moves and the ground loot actors are no longer being overlapped.
I have sort of got it working - when the actors are on their own the function seems to work. However, when two ground loot actors are close to one another, the inventory displays multiple widgets for the same overlapping actor on the floor and sometimes only recognises one of the actors on the floor. It seems to be having trouble when the Player's UBoxComponent overlaps more than one actor at a time. I'll link a YouTube video to help show the issue I'm having because it's quite hard to describe: https://youtu.be/a_zMl1zOUDc
This is the function for updating the ground loot widgets. It is called by a dynamic multicast delegate that is broadcasted from the player class:
// Iterates through the ground loot around the player and displays a widget for each item
void UInventory::UpdateGroundLoot()
{
MyPlayer = Cast<AMainCharacter>(GetOwningPlayer()->GetCharacter());
if(!MyPlayer) { return; } // Null check
// Get a ref to the Player's inventory component
UInventoryComponent* PlayerInventoryComp = MyPlayer->PlayerInventory;
// Clear any current widgets in the ground loot list
GroundLootScrollBox->ClearChildren();
// GroundLootActorsArray is an array of AActors that gets added to/emptied based on AActors that overlap with the Player's UBoxComponent
if(!PlayerInventoryComp && !PlayerInventoryComp->GroundLootActorsArray.IsValidIndex(0)) { return; } // Null check
for(int32 i = 0; i < PlayerInventoryComp->GroundLootActorsArray.Num(); i++)
{
// Cast each element of the GroundLootItems array to AItem* GroundItem
AItem* GroundItem = Cast<AItem>(PlayerInventoryComp->GroundLootActorsArray[i]);
if(!GroundItem) { return; } // Null check
// Add GroundItem to a new array (GroundLootItemsArray). This is an array specifically of AItems (rather than AActors).
GroundLootItemsArray.Add(GroundItem);
GroundLootWidget = CreateWidget<UInventoryItemWidget>(GetOwningPlayer(), InventoryItemWidgetClass);
// Add each created widget to an array of widgets called GroundLootWidgetsArray
GroundLootWidgetsArray.Add(GroundLootWidget);
if(!GroundLootWidgetsArray.IsValidIndex(0) && !GroundLootItemsArray.IsValidIndex(0)) { return; } // Null check
// Display item specific names/thumbnails for each widget created
GroundLootWidgetsArray[i]->ItemName->SetText(GroundLootItemsArray[i]->ItemDisplayName);
GroundLootWidgetsArray[i]->Thumbnail->SetBrushFromTexture(GroundLootItemsArray[i]->Thumbnail);
// Add each array element of the GroundLootWidgetsArray to the scroll box in the widget blueprint
GroundLootScrollBox->AddChild(GroundLootWidgetsArray[i]);
}
}

Answer 1

DevilsD in the comments pointed me in the right direction here. There were two main issues I had.
The delegate that was designed to update the ground loot widgets was being broadcasted in a for loop for every element of the OverlappingActor array. I think this resulted in multiple widgets being displayed for the same actor. The code in the Player's class now looks like this (TriggerEnter and TriggerExit are called by the OnComponentBeginOverlap and OnComponentEndOverlap delegates in the constructor respectively) :
void AMainCharacter::TriggerEnter(UPrimitiveComponent* OverlappedComponent, AActor* OtherActor,
UPrimitiveComponent* OtherComp, int32 OtherBodyIndex, bool bFromSweep, const FHitResult& SweepResult)
{
bItemIsWithinRange = true;
// I think the TSubclassOf ensures that we only pickup AItem classes and it's children - rather than all actors on the ground
OverlappedComponent->GetOverlappingActors(OverlappingActors, TSubclassOf<AItem>(AItem::StaticClass()));
if(PlayerInventory && OverlappingActors.IsValidIndex(0))
{
for(auto& GroundItems : OverlappingActors)
{
PlayerInventory->AddItemToGroundLoot(GroundItems);
}
OnUpdateGroundLoot.Broadcast();
}
}
void AMainCharacter::TriggerExit(UPrimitiveComponent* OverlappedComponent, AActor* OtherActor,
UPrimitiveComponent* OtherComp, int32 OtherBodyIndex)
{
bItemIsWithinRange = false;
if(PlayerInventory && OverlappingActors.IsValidIndex(0))
{
for(auto& GroundItems : OverlappingActors)
{
PlayerInventory->GroundLootActorsArray.Remove(GroundItems);
}
OnUpdateGroundLoot.Broadcast();
OverlappingActors.Empty();
}
}
I wasn't emptying the GroundLootItemsArray every time I was updating the ground loot and so previous ground loot was being stored in this array on each new update. This also resulted in showing the same widget for two different actors. I have now set it to empty along with clearing the children of the scroll box before any widget creation takes place in the UInventory.cpp (which is a child of UUserWidget):
// Iterates through the ground loot around the player and displays a widget for each item
void UInventory::UpdateGroundLoot()
{
MyPlayer = Cast<AMainCharacter>(GetOwningPlayer()->GetCharacter());
if(!MyPlayer) { return; } // Null check
// Get a ref to the Player's inventory component
UInventoryComponent* PlayerInventoryComp = MyPlayer->PlayerInventory;
// Clear any current widgets in the ground loot list
GroundLootScrollBox->ClearChildren();
// Empties this array to prevent replication of Item specific information that gets sent to the widget (i.e., the thumbnail or the name of the item)
GroundLootItemsArray.Empty();
// GroundLootActorsArray is an array of AActors that gets added to/emptied based on AActors that overlap with the Player's UBoxComponent
if(!PlayerInventoryComp && !PlayerInventoryComp->GroundLootActorsArray.IsValidIndex(0)) { return; } // Null check
for(int32 i = 0; i < PlayerInventoryComp->GroundLootActorsArray.Num(); i++)
{
// Cast each element of the GroundLootItems array to AItem* GroundItem
AItem* GroundItem = Cast<AItem>(PlayerInventoryComp->GroundLootActorsArray[i]);
if(!GroundItem) { return; } // Null check
// Add GroundItem to a new array (GroundLootItemsArray). This is an array specifically of AItems (rather than AActors).
GroundLootItemsArray.AddUnique(GroundItem);
GroundLootWidget = CreateWidget<UInventoryItemWidget>(GetOwningPlayer(), InventoryItemWidgetClass);
// Add each created widget to an array of widgets called GroundLootWidgetsArray
GroundLootWidgetsArray.AddUnique(GroundLootWidget);
if(!GroundLootWidgetsArray.IsValidIndex(0) && !GroundLootItemsArray.IsValidIndex(0)) { return; } // Null check
// Display item specific names/thumbnails for each widget created
GroundLootWidgetsArray[i]->ItemName->SetText(GroundLootItemsArray[i]->ItemDisplayName);
GroundLootWidgetsArray[i]->Thumbnail->SetBrushFromTexture(GroundLootItemsArray[i]->Thumbnail);
// Add each array element of the GroundLootWidgetsArray to the scroll box in the widget blueprint
GroundLootScrollBox->AddChild(GroundLootWidgetsArray[i]);
}
}
I also changed the adding of actors/items to the arrays from Array.Add(Actor) to Array.AddUnique(Actor). I'm not sure if this was necessary but it made sense to me because I didn't want more than one of any given item accidently being added to the array.