Binding Overlap delegate in UBoxComponent subclass

Development Programming & Scripting
1

I’m new to c++ and can’t quite get a handle on delegate binding. I’m trying to write a class derived from UBoxComponent that binds to the OnComponentBeginOverlap dynamic multicast delegate.

I also have a dynamic array of primitive components declared for this class. What I would like this component to do is maintain an index of any and all components from other actors it is overlapping with. Here’s what I’ve got so far:

my h:

#pragma once

#include "Components/BoxComponent.h"
#include "FloorSensor.generated.h"

UCLASS()
class MYPROJECT_API UFloorSensor : public UBoxComponent
{
    GENERATED_BODY()

public:

    UFloorSensor(const FObjectInitializer& ObjectInitializer);
    
    FComponentBeginOverlapSignature StartOverlappingDelegate;
    
    UFUNCTION()
    void StartOverlappingDelegate(class AActor* OtherActor, class UPrimitiveComponent* OtherComp, int32 OtherBodyIndex, bool bFromSweep, const FHitResult& SweepResult);
    
    bool bIsOverlapping;
    
    // Stores overlapping components whose parent actor implements certain interface
    TArray<UPrimitiveComponent*> OverlappingComponents;
};

my ccp:

#include "MyProject.h"
#include "FloorSensor.h"

UFloorSensor::UFloorSensor(const FObjectInitializer& ObjectInitializer)
    : Super(ObjectInitializer)
{
	
}

void UFloorSensor::StartOverlappingDelegate(class AActor* OtherActor, class UPrimitiveComponent* OtherComp, int32 OtherBodyIndex, bool bFromSweep, const FHitResult& SweepResult)
{

}

I’m getting several errors:

error C2365: 'UFloorSensor::StartOverlappingDelegate' : redefinition; previous definition was 'data member'

error C2064: term does not evaluate to a function taking 5 arguments

I’d be hugely grateful for any help here.

2

Hello, jasputin

The error occurs because you have the same name StartOverlappingDelegate for the variable and for the function.

Hoep this helped!

Cheers!

3

Thanks for the reply. That makes sense. I guess I’m not sure what to do with the FComponentBeginOverlapSignature delegate type name in a derived class. Could you clue me in? I’m trying to follow the docs here (https://docs.unrealengine.com/latest/INT/Programming/UnrealArchitecture/Delegates/index.html) but can’t quite make sense of it.

4

Got it working pretty much by just leaving out the delegate type declaration (and getting the right delegate function signature. So now I really don’t know where/how to use FComponentBeginOverlapSignature, but I’ll open a separate question for that when the time comes.

Here’s relevant code:

h:

UFUNCTION()
void StartOverlappingDelegate(class AActor* OtherActor, class UPrimitiveComponent* OtherComp, int32 OtherBodyIndex, bool bFromSweep, const FHitResult & SweepResult);

ccp:

// In constructor
OnComponentBeginOverlap.AddDynamic(this, &UFloorSensor::StartOverlappingDelegate);

// member function defintion
void UFloorSensor::StartOverlappingDelegate(class AActor* OtherActor, class UPrimitiveComponent* OtherComp, int32 OtherBodyIndex, bool bFromSweep, const FHitResult & SweepResult)
{
    UE_LOG(LogTemp, Log, TEXT("Component started overlapping"));
}

This is pretty intuitive and I would have done this first off if I hadn’t read through all the delegates documentation.