Blueprint Child class of C++ crashes when opening full editor view

Development Programming & Scripting Blueprint
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1

Coming up with a problem, I’ve set up a custom Pawn child class named X. It allows me to compile no problem, but when I create a child BP class based on this pawn class, it keeps crashing the editor with Access violation reading location 0x0000000000000520. This happens when I click the Open in full view editor once the BP is created. Not sure why. The break point on this warning is on GENERATED_BODY() which makes me think it’s related to components hierarchy.

    X.h:
    
    #pragma once
    
    #include "GameFramework/Pawn.h"
    #include "CableComponent.h"
    #include "X.generated.h"
    
    UCLASS()
    class TUX_087_API AX : public APawn
    {
    	GENERATED_BODY()
    
    public:
    	// Sets default values for this pawn's properties
    	AX();
    
    	// Called when the game starts or when spawned
    	virtual void BeginPlay() override;
    	
    	// Called every frame
    	virtual void Tick( float DeltaSeconds ) override;
    
    	// Called to bind functionality to input
    	virtual void SetupPlayerInputComponent(class UInputComponent* InputComponent) override;
    
    	// Behavior
    	UPROPERTY(EditAnywhere, Category = "Behavior")
    	class UBehaviorTree* HangingMaruta_Behavior;
    
    	/// Components ///
    
    	// Scene
    	UPROPERTY(VisibleAnywhere, BlueprintReadOnly, Category = "Components")
    		USceneComponent* Scene;
    
    	// Stable end of Constraint
    	UPROPERTY(VisibleAnywhere, BlueprintReadOnly, Category = "Components")
    		UStaticMeshComponent* EndofChain;
    
    	// HangingMaruta Mesh
    	UPROPERTY(VisibleAnywhere, BlueprintReadOnly, Category = "Components")
    		UStaticMeshComponent* HangingMaruta;
    
    	// Physics Constraint
    	UPROPERTY(VisibleAnywhere, BlueprintReadOnly, Category = "Components")
    		UPhysicsConstraintComponent* Constraint;
    
    	// Grab Trigger
    	UPROPERTY(VisibleAnywhere, BlueprintReadOnly, Category = "Components")
    		UBoxComponent* ActionTrigger;
    
    	// EndGrabTrigger
    	UPROPERTY(VisibleAnywhere, BlueprintReadOnly, Category = "Components")
    		USphereComponent* EndGrabTrigger;
    
    	// Cable
    	UPROPERTY(VisibleAnywhere, BlueprintReadOnly, Category = "Components")
    		UCableComponent* Cable;
    
    	// SpotLight
    	UPROPERTY(VisibleAnywhere, BlueprintReadOnly, Category = "Components")
    		USpotLightComponent* Light;
    
    
    	/// Variables ///
    
    	// Is The Maruta already grabbing a target? 
    	UPROPERTY(EditAnywhere, BlueprintReadWrite, Category = "Components")
    		bool bIsGrabbingTarget;
    
    	// Is the player within Range?
    	UPROPERTY(VisibleAnywhere, BlueprintReadWrite, Category = "Components")
    		bool bPlayerIsInRange;
    
    	// New Clamped MaxWalkSpeed Value
    	UPROPERTY(VisibleAnywhere, BlueprintReadWrite, Category = "Components")
    		float NewMaxWalkSpeed;
    
    	UPROPERTY(VisibleAnywhere, BlueprintReadWrite, Category = "CharacterRef")
    	class AMyCharacterTest* CharacterRef;
    
    	// Grab Ability Cooldown Timer handle
    	FTimerHandle TimerHandle_GrabAbilityCD;


      X.cpp:

 #include "TUX_087.h"
 #include "X_AIController.h"
 #include "MyCharacterTest.h"
 #include "Runtime/AIModule/Classes/BehaviorTree/BlackboardComponent.h"
 #include "Runtime/Engine/Classes/PhysicsEngine/PhysicsConstraintComponent.h"
 #include "Runtime/Engine/Classes/PhysicsEngine/PhysicsConstraintActor.h"
 #include "Runtime/Engine/Classes/Kismet/KismetMathLibrary.h"
 #include "Runtime/Core/Public/Math/UnrealMathUtility.h"
 #include "CableComponent.h"
 #include "X.h"


// Sets default values
AX::AX()
{
// Set this pawn to call Tick() every frame.  You can turn this off to improve performance if you don't need it.
PrimaryActorTick.bCanEverTick = true;
AIControllerClass = AX_AIController::StaticClass();


// Create Components 
Scene = CreateDefaultSubobject<USceneComponent>("Scene");
EndofChain = CreateDefaultSubobject<UStaticMeshComponent>("EndofChain");
X= CreateDefaultSubobject<UStaticMeshComponent>("HangingMaruta");
Constraint = CreateDefaultSubobject<UPhysicsConstraintComponent>("Constraint");
ActionTrigger = CreateDefaultSubobject<UBoxComponent>("Trigger");
Cable = CreateDefaultSubobject<UCableComponent>("Cable");
EndGrabTrigger = CreateDefaultSubobject<USphereComponent>("EndTrigger");
Light = CreateDefaultSubobject<USpotLightComponent>("Light");

Scene->bAbsoluteRotation = true;

// Set Root
RootComponent = Scene;

// Attach RootComponent Child Components.
EndofChain->SetupAttachment(RootComponent);
X->SetupAttachment(RootComponent);
Constraint->SetupAttachment(RootComponent);
EndGrabTrigger->SetupAttachment(RootComponent);

// Attach XChild Components.
ActionTrigger->SetupAttachment(HangingMaruta);
Cable->SetupAttachment(HangingMaruta);
HangingMaruta->SetSimulatePhysics(true);

// Attach EndofChain Child Components.
Light->SetupAttachment(EndofChain);


// Add overlapping event on Trigger
ActionTrigger->OnComponentBeginOverlap.AddDynamic(this, &AX::SetTarget);
ActionTrigger->OnComponentEndOverlap.AddDynamic(this, &AX::ResetTarget);
EndGrabTrigger->OnComponentEndOverlap.AddDynamic(this, &AX::DetachTarget);


// Clamp Max Walk Speed value
//NewMaxWalkSpeed = 600.f;
 }
2

I think it would help to see the definition of your parent-class and what you declared inside it.

3

Woops, Thanks… there’s the code of the custom class. I was also able to reproduce this error in another project.

4

Here’s a look at the exception being thrown.

119934-x.png
119934-x.png1404×506 28.6 KB

5

How can an exception be thrown in a class-definition?.. Especially in a line that’s only for the pre-processor? Lol, anyway. I would try to move function-calls on components out of the constructor and into an override of PostInitializeComponents. Maybe this helps.

edit: I’m thinking about SetSimulatePhysics in particular. Isn’t there also a bool for that? I don’t remember at the moment. If so, you could also try to set the bool inside the constructor, instead of calling the function.

6

So I’ve finally worked it out, apperantly the problem was with a function I had setting Blackboard values. In addition to fixing some collisions with the ActionTrigger. Thanks anyways for the feedback! I’ll see about moving those function calls to PostInitialize.