给 DefaultPawn_Blueprint 添加组件 Phusics Handle

（对蓝图做的修改都要保存和编译）添加完组件后，需要 Save 和 编译

使用Physics Handle 需要引入的头文件 #include "PhysicsEngine/PhysicsHandleComponent.h"

不知道用头文件，使用谷歌搜索一下，看官方的文档里面找

使用 UPhysicsHandleComponent* ，需要引入头文件 #include "PhysicsEngine/PhysicsHandleComponent.h"

没有引入组件导致的报错：

引入#include "Components/PrimitiveComponent.h"

使用UPrimitiveComponent* 需要引入 #include "Components/PrimitiveComponent.h"

没有抓起来，Actor是 可移动的

// Grabber.h
#pragma once

#include "CoreMinimal.h"
#include "Components/ActorComponent.h"
#include "Components/InputComponent.h"
#include "PhysicsEngine/PhysicsHandleComponent.h"
#include "Grabber.generated.h"


UCLASS( ClassGroup=(Custom), meta=(BlueprintSpawnableComponent) )
class UNREALENGINEPROJECT_API UGrabber : public UActorComponent
{
	GENERATED_BODY()

public:	
	UGrabber();

protected:
	virtual void BeginPlay() override;

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

private:
	FVector GetLineStart();
	FVector GetLineEnd();
	FHitResult LineTrace();
	UInputComponent* InputComponent = nullptr;
	UPhysicsHandleComponent* PhysicsHandle = nullptr;
	void Grab();
	void Release();
};

// Grabber.cpp


#include "Grabber.h"
#include "Engine/World.h"
#include "DrawDebugHelpers.h"
#include "Components/PrimitiveComponent.h"

UGrabber::UGrabber()
{
	PrimaryComponentTick.bCanEverTick = true;
}


void UGrabber::BeginPlay()
{
	Super::BeginPlay();

	PhysicsHandle = GetOwner()->FindComponentByClass<UPhysicsHandleComponent>();

	InputComponent = GetOwner()->FindComponentByClass<UInputComponent>();

	if (InputComponent)// 使用指针需要判断不为空
	{
		UE_LOG(LogTemp, Warning, TEXT("Input Component is founded!"));
		InputComponent->BindAction("Grab", IE_Pressed, this, &UGrabber::Grab);
		InputComponent->BindAction("Grab", IE_Released, this, &UGrabber::Release);
	}
	else
	{
		UE_LOG(LogTemp, Error, TEXT("Input Component is not founded!"));
	}
	
}


void UGrabber::TickComponent(float DeltaTime, ELevelTick TickType, FActorComponentTickFunction* ThisTickFunction)
{
	Super::TickComponent(DeltaTime, TickType, ThisTickFunction);
}

FVector UGrabber::GetLineStart()
{
	FVector Start;
	FRotator ViewRotator;
	GetWorld()->GetFirstPlayerController()->GetPlayerViewPoint(Start, ViewRotator);
	return Start;
}

FVector UGrabber::GetLineEnd()
{
	FVector Start;
	FRotator ViewRotator;
	GetWorld()->GetFirstPlayerController()->GetPlayerViewPoint(Start, ViewRotator);
	return (Start + ViewRotator.Vector() * 100); // ViewRotator.Vector() 视野的正中心 前方 100cm
}

FHitResult  UGrabber::LineTrace()
{
	//DrawDebugLine(GetWorld(), Start, End, FColor(255, 0, 0), false, 0, 0, 10);

	FHitResult Hit;
	GetWorld()->LineTraceSingleByObjectType(
		Hit,
		GetLineStart(),
		GetLineEnd(),
		FCollisionObjectQueryParams(ECollisionChannel::ECC_PhysicsBody),
		FCollisionQueryParams(FName(TEXT("")), false, GetOwner())
	);
	AActor* Actor = Hit.GetActor();
	if (Actor != nullptr)
	{
		UE_LOG(LogTemp, Warning, TEXT("Line Hit:%s"), *Actor->GetName());
	}
	return Hit;
}

void UGrabber::Grab()
{
	UE_LOG(LogTemp, Warning, TEXT("Grab action is pressed!"));
	FHitResult Hit = LineTrace();
	UPrimitiveComponent* ComponentToGrab = Hit.GetComponent();
	if (Hit.GetActor() && PhysicsHandle)
	{
		UE_LOG(LogTemp, Warning, TEXT("Grab!"));
		//PhysicsHandle->GrabComponent(ComponentToGrab, NAME_None, ComponentToGrab->GetOwner()->GetActorLocation(), true); // 已弃用
		PhysicsHandle->GrabComponentAtLocation(ComponentToGrab, NAME_None, ComponentToGrab->GetOwner()->GetActorLocation());
	}
}

void UGrabber::Release()
{
	UE_LOG(LogTemp, Error, TEXT("Grab action is released!"));
}