How to use OnActorBeginOverlap in UE4 C++ - c++

Question

I'm working on a small game in UE4 and hit a small issue.
So far, I've got the player dealing damage to enemies (via raycast/line trace) all in C++. Now I'm trying to make the enemy cause damage to the player when their collision boxes overlap.
The player uses the TakeDamage() function as does the enemy to deal damage to each other.
Currently, the enemy does deal damage to the player with this Blueprint setup when both of the collisons overlap.
I'm trying to translate this into C++.
I have been looking at many websites which say to use either OnActorBeginOverlap() or OnComponentBeginOverlap() with the AddDynamic() function. However, when trying to call OnActorBeginOverlap() it doesn't appear when I do BoxCollider-> but OnComponentBeginOverlap() does, but does not have the AddDynamic() function. From what I understand, AddDynamic is a macro which I'm not too familiar with. OnActorBeginOverlap() does appear without the BoxCollider->. Both objects are Actors.
Any ideas?
Code Example:
BasicZombie.h
#pragma once
#include "CoreMinimal.h"
#include "GameFramework/Actor.h"
#include "Components/BoxComponent.h"
#include "BasicZombie.generated.h"
UCLASS()
class MERCENARIES_API ABasicZombie : public AActor
{
GENERATED_BODY()
public:
// Sets default values for this actor's properties
ABasicZombie();
void Destroy();
UPROPERTY(EditAnywhere)
UBoxComponent* BoxCollider;
protected:
// Called when the game starts or when spawned
virtual void BeginPlay() override;
virtual float TakeDamage(float DamageAmount, struct FDamageEvent const& DamageEvent, class AController* EventInstigator, AActor* DamageCauser) override;
private:
UPROPERTY(EditDefaultsOnly)
float maxHealth = 100.0f;
UPROPERTY(VisibleAnywhere)
float health;
void DealDamage();
public:
// Called every frame
virtual void Tick(float DeltaTime) override;
};
BasicZombie.cpp
#include "BasicZombie.h"
#include "MainCharacter.h"
#include "GameFramework/Actor.h"
#include "DrawDebugHelpers.h"
#include "Engine/Engine.h"
// Sets default values
ABasicZombie::ABasicZombie()
{
// Set this actor to call Tick() every frame. You can turn this off to improve performance if you don't need it.
PrimaryActorTick.bCanEverTick = false;
BoxCollider = CreateDefaultSubobject<UBoxComponent>(TEXT("BoxCollider"));
BoxCollider->OnComponentBeginOverlap.AddDynamic(this, &AMainCharacter::OnCollision);
health = maxHealth;
}
// Called when the game starts or when spawned
void ABasicZombie::BeginPlay()
{
Super::BeginPlay();
}
float ABasicZombie::TakeDamage(float DamageAmount, struct FDamageEvent const& DamageEvent, class AController* EventInstigator, AActor* DamageCauser)
{
float DamageToApply = Super::TakeDamage(DamageAmount, DamageEvent, EventInstigator, DamageCauser);
DamageToApply = FMath::Min(health, DamageToApply);
health -= DamageToApply;
UE_LOG(LogTemp, Warning, (TEXT("Health Remaining: %f")), health);
//GEngine->AddOnScreenDebugMessage(-1, 3.0f, FColor::Red, FString::Printf(TEXT("Health Remaining: %f"), health));
Destroy();
return DamageToApply;
}
//void ABasicZombie::DealDamage()
//{
//
//}
void ABasicZombie::Destroy()
{
if (health <= 0)
{
UWorld* WorldRef = GetWorld();
AMainCharacter* mainCharacter = Cast<AMainCharacter>(WorldRef->GetFirstPlayerController()->GetCharacter());
mainCharacter->currentScore += 500;
GEngine->AddOnScreenDebugMessage(-1, 3.0f, FColor::Green, FString::Printf(TEXT("Score: %i"), mainCharacter->currentScore));
AActor::Destroy();
}
}
// Called every frame
void ABasicZombie::Tick(float DeltaTime)
{
Super::Tick(DeltaTime);
}
MainCharacter.h
// Fill out your copyright notice in the Description page of Project Settings.
#pragma once
#include "CoreMinimal.h"
#include "GameFramework/Character.h"
#include "Camera/CameraComponent.h"
#include "Components/CapsuleComponent.h"
#include "Components/InputComponent.h"
#include "GameFramework/PlayerController.h"
#include "MainCharacter.generated.h"
class AHandgun;
UCLASS()
class MERCENARIES_API AMainCharacter : public ACharacter
{
GENERATED_BODY()
public:
// Sets default values for this character's properties
AMainCharacter();
void OnCollision(UPrimitiveComponent* OverlappedComponent, AActor* OtherActor, UPrimitiveComponent* OtherComponent, int32 OtherBodyIndex, bool bFromSweep, const FHitResult& Hit);
protected:
// Called when the game starts or when spawned
virtual void BeginPlay() override;
virtual float TakeDamage(float DamageAmount, struct FDamageEvent const& DamageEvent, class AController* EventInstigator, AActor* DamageCauser) override;
private:
UPROPERTY(EditDefaultsOnly)
TSubclassOf<AHandgun> HandgunClass;
UPROPERTY()
AHandgun* Handgun;
public:
// Called every frame
virtual void Tick(float DeltaTime) override;
// Called to bind functionality to input
virtual void SetupPlayerInputComponent(class UInputComponent* PlayerInputComponent) override;
//Handles Input for moving FORWARD and BACK
UFUNCTION()
void MoveForward(float value);
//Handles input for moving RIGHT and LEFT
UFUNCTION()
void MoveRight(float value);
UFUNCTION()
void Shoot();
UFUNCTION()
void printHealth();
//FPS camera
UPROPERTY(VisibleAnywhere)
UCameraComponent* MainCharacterCameraComponent;
UPROPERTY(EditAnywhere, BlueprintReadWrite, Category = Gameplay)
FVector MuzzleOffset;
UPROPERTY()
int32 playerScore;
UPROPERTY()
int32 currentScore;
UPROPERTY()
float maxHealth = 1000.0f;
UPROPERTY(EditAnywhere, BlueprintReadWrite)
float currentHealth;
};
MainCharacter.cpp
// Fill out your copyright notice in the Description page of Project Settings.
#include "MainCharacter.h"
#include "Engine/Engine.h"
#include "GameFramework/Actor.h"
#include "Handgun.h"
#include "GameFramework/Character.h"
#include "Components/SkeletalMeshComponent.h"
// Sets default values
AMainCharacter::AMainCharacter()
{
// Set this character to call Tick() every frame. You can turn this off to improve performance if you don't need it.
PrimaryActorTick.bCanEverTick = true;
//Create a first person camera component
MainCharacterCameraComponent = CreateDefaultSubobject<UCameraComponent>(TEXT("FirstPersonCamera"));
check(MainCharacterCameraComponent != nullptr);
//Attach the camera component to our capsule component
MainCharacterCameraComponent->SetupAttachment(CastChecked<USceneComponent, UCapsuleComponent>(GetCapsuleComponent()));
//Position the camera slightly above the eyes
MainCharacterCameraComponent->SetRelativeLocation(FVector(0.0f, 0.0f, 50.0f + BaseEyeHeight));
//Enable the pawn to control camera rotation
MainCharacterCameraComponent->bUsePawnControlRotation = true;
currentHealth = maxHealth;
playerScore = currentScore;
}
// Called when the game starts or when spawned
void AMainCharacter::BeginPlay()
{
Super::BeginPlay();
check(GEngine != nullptr);
GEngine->AddOnScreenDebugMessage(-1, 5.0f, FColor::Yellow, TEXT("[MainCharacter DEBUG] - MainCharacter in use."));
GEngine->AddOnScreenDebugMessage(-1, 5.0f, FColor::Green, FString::Printf(TEXT("[MainCharacter DEBUG] - Current Score: %f"), playerScore));
Handgun = GetWorld()->SpawnActor<AHandgun>(HandgunClass);
Handgun->AttachToComponent(GetMesh(), FAttachmentTransformRules::KeepRelativeTransform, TEXT("WeaponSocket"));
Handgun->SetOwner(this);
}
// Called every frame
void AMainCharacter::Tick(float DeltaTime)
{
Super::Tick(DeltaTime);
//printHealth();
}
// Called to bind functionality to input
void AMainCharacter::SetupPlayerInputComponent(UInputComponent* PlayerInputComponent)
{
Super::SetupPlayerInputComponent(PlayerInputComponent);
//Set up movement bindings.
PlayerInputComponent->BindAxis("MoveForward", this, &AMainCharacter::MoveForward);
PlayerInputComponent->BindAxis("MoveRight", this, &AMainCharacter::MoveRight);
//Set up Look Bindings
PlayerInputComponent->BindAxis("Turn", this, &AMainCharacter::AddControllerYawInput);
PlayerInputComponent->BindAxis("LookUp", this, &AMainCharacter::AddControllerPitchInput);
//Setup Weapon Shooting
PlayerInputComponent->BindAction(TEXT("Fire"), EInputEvent::IE_Pressed, this, &AMainCharacter::Shoot);
PlayerInputComponent->BindAction(TEXT("printHealth"), EInputEvent::IE_Pressed, this, &AMainCharacter::printHealth);
}
void AMainCharacter::Shoot()
{
Handgun->Shoot();
}
void AMainCharacter::printHealth()
{
GEngine->AddOnScreenDebugMessage(-1, 5.0f, FColor::Green, FString::Printf(TEXT("[MainCharacter DEBUG] - Current Health: %f"), currentHealth));
}
float AMainCharacter::TakeDamage(float DamageAmount, struct FDamageEvent const& DamageEvent, class AController* EventInstigator, AActor* DamageCauser)
{
float DamageToApply = Super::TakeDamage(DamageAmount, DamageEvent, EventInstigator, DamageCauser);
DamageToApply = FMath::Min(currentHealth, DamageToApply);
currentHealth -= DamageToApply;
GEngine->AddOnScreenDebugMessage(-1, 3.0f, FColor::Red, FString::Printf(TEXT("Health Remaining: %f"), currentHealth));
if (currentHealth <= 0)
{
GEngine->AddOnScreenDebugMessage(-1, 3.0f, FColor::Red, TEXT("You're Dead!"));
}
return DamageAmount;
}
void AMainCharacter::MoveForward(float value)
{
//Find out which way is "forward" and reocrd that the player wants to move that way
FVector Direction = FRotationMatrix(Controller->GetControlRotation()).GetScaledAxis(EAxis::X);
AddMovementInput(Direction, value);
}
void AMainCharacter::MoveRight(float value)
{
//Find out which way is "right" and record that the player wants to move that way
FVector Direction = FRotationMatrix(Controller->GetControlRotation()).GetScaledAxis(EAxis::Y);
AddMovementInput(Direction, value);
}
However, the BoxCollider->OnComponentBeginOverlap.AddDynamic(this, &AMainCharacter::OnCollision); in BasicZombie.cpp has a red line under AddDynamic.
I am in a Discord Server for UE4 development, but I haven't had much luck getting any help from there.

Answer 1

Can I see your C++ code? Are you calling AddDynamic from the UBoxComponent?
Try this
UPROPERTY(EditAnywhere)
UBoxComponent* BoxCollider = nullptr;
BoxCollider = GetOwner()->FindComponentByClass<UBoxComponent>();
BoxCollider->OnComponentBeginOverlap.AddDynamic(this, &YourActor::OnCollision);
Use this as your OnCollision signature
void OnCollision(UPrimitiveComponent* OverlappedComponent, AActor* OtherActor, UPrimitiveComponent* OtherComponent, int32 OtherBodyIndex, bool bFromSweep, const FHitResult& Hit);
Also when I was learning unreal engine I dealt with a lot of pitfalls. Try to find a community of unreal engine developers and learn with them.