Problem with AttributeSet Getters and Delegates

Development Programming & Scripting C++
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1

Recently I started to learn Gameplay Ability System and I have a problem regarding AttributeSet, Getters and Delegates that respond to Attribute changes. I have my Ability System Component created on MainCharacter which is Base Class for my future Characters I then derived CharacterPaladin class from it. I decided to create PlayerState when I will respond to all Attribute changes. However my game crashes when I use one of the AttributeSet Getters.

Crash LOG:

LoginId:f119695349758d2c727103ac0b900461
EpicAccountId:6f905fcc596f42b99f3aa89bdc239b69

Unhandled Exception: EXCEPTION_ACCESS_VIOLATION reading address 0x000000000000004c

UnrealEditor_GameplayAbilities
UnrealEditor_Projekt!AMainPlayerState::HealthChanged() [E:\WS_Ramen\Projekt\Source\Projekt\MainPlayerState.cpp:67]
UnrealEditor_Projekt!TBaseUObjectMethodDelegateInstance<0,AMainPlayerState,void __cdecl(FOnAttributeChangeData const &),FDefaultDelegateUserPolicy>::ExecuteIfSafe() [E:\UnrealEngine5\UE_5.0\Engine\Source\Runtime\Core\Public\Delegates\DelegateInstancesImpl.h:611]
UnrealEditor_GameplayAbilities
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UnrealEditor_UnrealEd
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kernel32
ntdll

These are my getters from AMainCharacter

AMainCharacter.h

	virtual class UAbilitySystemComponent* GetAbilitySystemComponent() const override;

	class UGASAttributeSet* GetPlayerAttributeSetBase() const;

AMainCharacter.cpp

UAbilitySystemComponent* AMainCharacter::GetAbilitySystemComponent() const
{
	return AbilitySystemComponent;
}
UGASAttributeSet* AMainCharacter::GetPlayerAttributeSetBase() const
{
	return Attributes;
}

And this is my MainPlayerState class

MainPlayerState.h

// Fill out your copyright notice in the Description page of Project Settings.

#pragma once

#include "CoreMinimal.h"
#include "GameFramework/PlayerState.h"
#include "GameplayTagContainer.h"
#include "GASAttributeSet.h"
#include "MainPlayerState.generated.h"

/**
 * 
 */
UCLASS()
class PROJEKT_API AMainPlayerState : public APlayerState
{
	GENERATED_BODY()

public:
	AMainPlayerState();
	
	UFUNCTION(BlueprintCallable, Category = "PlayerCharacter|MainPlayerState")
	bool IsAlive() const;

	//Getters for attributes
	UFUNCTION(BlueprintCallable, Category = "GAS|BaseCharacter|Attributes")
	float GetHealth() const;

	UFUNCTION(BlueprintCallable, Category = "GAS|BaseCharacter|Attributes")
	float GetMaxHealth() const;

	UFUNCTION(BlueprintCallable, Category = "GAS|BaseCharacter|Attributes")
	float GetResource() const;

	UFUNCTION(BlueprintCallable, Category = "GAS|BaseCharacter|Attributes")
	float GetMaxResource() const;

protected:
	UPROPERTY()
	class UGASAbilitySystemComponent* PlayerAbilitySystemComponent;
	
	UPROPERTY()
	class UGASAttributeSet* PlayerAttributeSetBase;

	FGameplayTag DeadTag;

	FDelegateHandle HealthChangedDelegateHandle;
	FDelegateHandle MaxHealthChangedDelegateHandle;
	FDelegateHandle ResourceChangedDelegateHandle;
	FDelegateHandle MaxResourceChangedDelegateHandle;

	virtual void BeginPlay() override;

	// Attribute changed callbacks
	virtual void HealthChanged(const FOnAttributeChangeData& Data);
	virtual void MaxHealthChanged(const FOnAttributeChangeData& Data);
	virtual void ResourceChanged(const FOnAttributeChangeData& Data);
	virtual void MaxResourceChanged(const FOnAttributeChangeData& Data);
};


MainPlayerState.cpp

// Fill out your copyright notice in the Description page of Project Settings.


#include "MainPlayerState.h"
#include "GASAbilitySystemComponent.h"
#include "MainCharacter.h"
#include "GASAttributeSet.h"
#include "UPlayerResourceWidget.h"

AMainPlayerState::AMainPlayerState()
{
	DeadTag = FGameplayTag::RequestGameplayTag(FName("StateTag.Dead"));
}

bool AMainPlayerState::IsAlive() const
{
	return GetHealth() > 0.0f;
}

float AMainPlayerState::GetHealth() const
{
	AMainCharacter* Player = Cast<AMainCharacter>(GetPawn());
	return Player->GetPlayerAttributeSetBase()->GetHealth();
}

float AMainPlayerState::GetMaxHealth() const
{
	return PlayerAttributeSetBase->GetMaxHealth();
}

float AMainPlayerState::GetResource() const
{
	return PlayerAttributeSetBase->GetResource();
}

float AMainPlayerState::GetMaxResource() const
{
	return PlayerAttributeSetBase->GetMaxResource();
}

void AMainPlayerState::BeginPlay()
{
	Super::BeginPlay();
	GEngine->AddOnScreenDebugMessage(-1,2,FColor::Red,TEXT("Entered Begin play"));
	
	AMainCharacter* Player = Cast<AMainCharacter>(GetPawn());
	if(Player)
	{
		PlayerAbilitySystemComponent = Cast<UGASAbilitySystemComponent>(Player->GetAbilitySystemComponent());
		PlayerAttributeSetBase = Player->GetPlayerAttributeSetBase();
		
		if(PlayerAbilitySystemComponent)
		{
			GEngine->AddOnScreenDebugMessage(-1,2,FColor::Red,TEXT("Entered creating Delegets"));
			
			HealthChangedDelegateHandle = PlayerAbilitySystemComponent->GetGameplayAttributeValueChangeDelegate(PlayerAttributeSetBase->GetHealthAttribute()).AddUObject(this,&AMainPlayerState::HealthChanged);
			MaxHealthChangedDelegateHandle = PlayerAbilitySystemComponent->GetGameplayAttributeValueChangeDelegate(PlayerAttributeSetBase->GetMaxHealthAttribute()).AddUObject(this, &AMainPlayerState::MaxHealthChanged);
			ResourceChangedDelegateHandle = PlayerAbilitySystemComponent->GetGameplayAttributeValueChangeDelegate(PlayerAttributeSetBase->GetResourceAttribute()).AddUObject(this, &AMainPlayerState::ResourceChanged);
			MaxResourceChangedDelegateHandle = PlayerAbilitySystemComponent->GetGameplayAttributeValueChangeDelegate(PlayerAttributeSetBase->GetMaxResourceAttribute()).AddUObject(this, &AMainPlayerState::MaxResourceChanged);
		}
	}
	
}

void AMainPlayerState::HealthChanged(const FOnAttributeChangeData& Data)
{
	float Health = Data.NewValue;
	GEngine->AddOnScreenDebugMessage(-1,2,FColor::Red,FString::Printf(TEXT("Health: %f"),GetHealth()));
	
	AMainCharacter* Player = Cast<AMainCharacter>(GetPawn());
	
		UUPlayerResourceWidget* PlayerResourceWidget = Player->GetFloatingResourceWidget();
		if(PlayerResourceWidget)
		{
			GEngine->AddOnScreenDebugMessage(-1,2,FColor::Red,TEXT("Entered Health Changed"));
			PlayerResourceWidget->SetHeathPercentage(Health / GetMaxHealth());
			
		}
	

	/*
	if(!IsAlive())
	{
		if(Player)
		{
			//TODO Call Die function here
			GEngine->AddOnScreenDebugMessage(-1,4,FColor::Red,TEXT("PLAYER DIED"));
		}
	}
	*/
}

void AMainPlayerState::MaxHealthChanged(const FOnAttributeChangeData& Data)
{
	float MaxHealth = Data.NewValue;
	
	AMainCharacter* Player = Cast<AMainCharacter>(GetPawn());
	if(Player)
	{
		UUPlayerResourceWidget* PlayerResourceWidget = Player->GetFloatingResourceWidget();
		if(PlayerResourceWidget)
		{
			PlayerResourceWidget->SetHeathPercentage(GetHealth() / MaxHealth);
		}
	}
}

void AMainPlayerState::ResourceChanged(const FOnAttributeChangeData& Data)
{
	float Resource = Data.NewValue;

	AMainCharacter* Player = Cast<AMainCharacter>(GetPawn());
	if(Player)
	{
		UUPlayerResourceWidget* PlayerResourceWidget = Player->GetFloatingResourceWidget();
		if(PlayerResourceWidget)
		{
			PlayerResourceWidget->SetManaPercentage(Resource / GetMaxResource());
		}
	}
}

void AMainPlayerState::MaxResourceChanged(const FOnAttributeChangeData& Data)
{
	float MaxResource = Data.NewValue;

	
	AMainCharacter* Player = Cast<AMainCharacter>(GetPawn());
	if(Player)
	{
		UUPlayerResourceWidget* PlayerResourceWidget = Player->GetFloatingResourceWidget();
		if(PlayerResourceWidget)
		{
			PlayerResourceWidget->SetManaPercentage(GetResource() / MaxResource);
		}
	}
}
2

I have the same issue. Same exception. No workaround at present.

Attempting to access data via Getter results in EXCEPTION_ACCESS_VIOLATION.

3

Hey, looking back at this I think that initialization of ASC and Attributes in BeginPlay() in PlayerState may be too late. I recommend looking at: GitHub - tranek/GASDocumentation: My understanding of Unreal Engine 5's GameplayAbilitySystem plugin with a simple multiplayer sample project. as this approach of creating AbilitySystemComponent and AttributeSet is better than what I’ve done here, alternatively you can try to initialize it in the constructor or switch to your Character class for binding the delegates if you’re okay with the clutter. Anyway imo it will be best to look at the GASDocumentation as this approach seems to be the best (Epic also uses it in Fortnite).