Section: Building Escape Original. :Lecture: "Using Physics Handles"

[Ashton_Fox]

I am having some errors with the fowling code:

The .h FIle:

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

#pragma once

#include "DrawDebugHelpers.h"
#include "CoreMinimal.h"
#include "Components/ActorComponent.h"
#include "GameFramework/Controller.h"
#include "Public/CollisionQueryParams.h"
#include "PhysicsEngine/PhysicsHandleComponent.h"
#include "Components/InputComponent.h"
#include "PhysicsEngine/PhysicsHandleComponent.h"
#include "DrawDebugHelpers.h"
#include "CoreMinimal.h"
#include "Components/ActorComponent.h"
#include "garbberComponet.generated.h"


UCLASS( ClassGroup=(Custom), meta=(BlueprintSpawnableComponent) )
class BUILDINGESCSPEORGIN_API UgarbberComponet : public UActorComponent
{
	GENERATED_BODY()

public:	
	// Sets default values for this component's properties
	UgarbberComponet();

	void Grab();
	void Release();
	void FindPhysicsHandleComponent();
	void SetUpEveryFrame();
	const FHitResult GetFirstPhysicsBodyInReach();

	UPROPERTY(EditAnywhere)
	float Reach = 100.0f;
	UPhysicsHandleComponent* PhysicsHandle = nullptr;
	UInputComponent* InputComponent = nullptr;

protected:
	// Called when the game starts
	virtual void BeginPlay() override;

public:	
	// Called every frame
	virtual void TickComponent(float DeltaTime, ELevelTick TickType, FActorComponentTickFunction* ThisTickFunction) override;

		
};

The .cpp file:

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

#include "garbberComponet.h"
#include "DrawDebugHelpers.h"
#include "CoreMinimal.h"
#include "Components/ActorComponent.h"
#include "GameFramework/Controller.h"
#include "Public/CollisionQueryParams.h"
#include "PhysicsEngine/PhysicsHandleComponent.h"
#include "Components/PrimitiveComponent.h"
#include "Engine/World.h"

// Sets default values for this component's properties
UgarbberComponet::UgarbberComponet()
{
	// Set this component to be initialized when the game starts, and to be ticked every frame.  You can turn these features
	// off to improve performance if you don't need them.
	PrimaryComponentTick.bCanEverTick = true;

	// ...
}

// Called when the game starts
void UgarbberComponet::BeginPlay()
{
	Super::BeginPlay();

	// ...
}

void UgarbberComponet::Grab()
{
	auto HitResult = GetFirstPhysicsBodyInReach();
	auto ComponentToGrab = HitResult.GetComponent();
	auto ActorHit = HitResult.GetActor();

	if(ActorHit)
	{
PhysicsHandle -> GrabComponentAtLocation(ComponentToGrab, NAME_None, ComponentToGrab -> GetOwner() -> GetActorLocation());
	}
}
void UgarbberComponet::Release()
{

}
// Called every frame
void UgarbberComponet::TickComponent(float DeltaTime, ELevelTick TickType, FActorComponentTickFunction *ThisTickFunction)
{
	Super::TickComponent(DeltaTime, TickType, ThisTickFunction);

		FVector PlayerVeiwpointLocation;
	FRotator PlayerVeiwpointRotation;
		FCollisionQueryParams TracePerams = (FName(TEXT("")), false, GetOwner());
	const FVector LineTraceEnd = PlayerVeiwpointLocation + PlayerVeiwpointRotation.Vector() * Reach;
	FHitResult* Hit;
	GetWorld()->LineTraceSingleByObjectType(*Hit, PlayerVeiwpointLocation, LineTraceEnd, FCollisionObjectQueryParams(ECollisionChannel::ECC_PhysicsBody), TracePerams);
	AActor *ActorHit = Hit->GetActor();
	InputComponent = GetOwner()->FindComponentByClass<UInputComponent>();

	PhysicsHandle -> SetTargetLocation(LineTraceEnd);


	// ...
}
void UgarbberComponet::FindPhysicsHandleComponent()
{
		PhysicsHandle = GetOwner()->FindComponentByClass<UPhysicsHandleComponent>();
}
	const FHitResult UgarbberComponet::GetFirstPhysicsBodyInReach()
	{
if (InputComponent)
	{
		InputComponent->BindAction("Grab", IE_Pressed, this, UgarbberComponet::Grab());
		InputComponent->BindAction("Grab", IE_Released, this, UgarbberComponet::Release());
	}
	else
	{
	}
		if(PhysicsHandle -> GrabbedComponent)
	{
			FVector PlayerVeiwpointLocation;
	FRotator PlayerVeiwpointRotation;
		FCollisionQueryParams TracePerams = (FName(TEXT("")), false, GetOwner());
	const FVector LineTraceEnd = PlayerVeiwpointLocation + PlayerVeiwpointRotation.Vector() * Reach;
	FHitResult* Hit;
	GetWorld()->LineTraceSingleByObjectType(*Hit, PlayerVeiwpointLocation, LineTraceEnd, FCollisionObjectQueryParams(ECollisionChannel::ECC_PhysicsBody), TracePerams);
	AActor *ActorHit = Hit->GetActor();
	InputComponent = GetOwner()->FindComponentByClass<UInputComponent>();

	PhysicsHandle -> SetTargetLocation(LineTraceEnd);
	return FHitResult();
	}

Thank You

[DanM]

I asked on Udemy for you to actually state what the problem here but formatting your post correctly I saw this

FHitResult* Hit;
GetWorld()->LineTraceSingleByObjectType(*Hit, PlayerVeiwpointLocation, LineTraceEnd, FCollisionObjectQueryParams(ECollisionChannel::ECC_PhysicsBody), TracePerams);

Hit should not be a pointer, dereferencing it on the next line would most definitely be a crash since it’s not pointing to anything and also

return FHitResult();

Your returning a default initialised FHitResult object and not the variable which has the correct values (once the above issue is fixed)

[Ashton_Fox]

Thank You, It seams to be working now