UE4 C++：Actor与Component的创建、销毁

目录

Actor的创建与销毁

创建

UClass*

TSubclassOf

SpawnActor()

销毁

直接销毁：Destroy()

设置生命周期

Component 的创建与销毁

创建

构造函数创建：CreateDefaultSubobject

Runtime创建：NewObject、RegisterComponent()

加载资源

FObjectFinder构造函数加载资源

LoadObject加载资源

设置组件层级关系

销毁组件

各类组件创建与初始化

UStaticMenshComponent

UBoxComponent

USphereComponent

USkeletalMeshComponent

USpringArmComponent和UCameraComponent

UPhysicsThrusterComponent

UTexRenderComponent

UProjectileMovementComponent

---

Actor的创建与销毁

创建

UClass*

TSubclassOf<T>

SpawnActor()

UPROPERTY(EditAnywhere, Category = "init")
	UClass* bullet0; // 取类

UPROPERTY(EditAnywhere, Category = "init")
	TSubclassOf<Amissile> bullet; //取Amissile类及其派生类

UPROPERTY(EditAnywhere, Category = "init")
	Amissile* bullet2; // 取类的实例

销毁

直接销毁：Destroy()

MissileIns->Destroy();

设置生命周期

构造函数设置InitialLifeSpan

InitialLifeSpan = 8.0f;

BeginPlay里使用SetLifeSpan()设置声明周期

Component 的创建与销毁

创建

构造函数创建：CreateDefaultSubobject<T>

UPROPERTY(VisibleAnywhere)
	UStaticMeshComponent* paddle1;

paddle1 = CreateDefaultSubobject<UStaticMeshComponent>(TEXT("paddle1"));

Runtime创建：NewObject<T>、RegisterComponent()

Mesh = NewObject<UStaticMeshComponent>(this,TEXT("MyMesh"));
Mesh->SetupAttachment(root);
Mesh->RegisterComponent(); // 注册渲染/物理状态
// 可配合 LoadObject() 

加载资源

FObjectFinder构造函数加载资源

• ConstructorHelpers::FObjectFinder<T>

static ConstructorHelpers::FObjectFinder<UStaticMesh> paddleMesh(TEXT("StaticMesh'/Game/Demo_Drone/SM/paddle.paddle'"));
if (paddleMesh.Succeeded())
{
	paddle1->SetStaticMesh(paddleMesh.Object);
}

LoadObject加载资源

UStaticMesh* bodyMesh = LoadObject<UStaticMesh>(this,TEXT("StaticMesh'/Game/Demo_Drone/SM/drone.drone'"));
if (bodyMesh)
{
	body->SetStaticMesh(bodyMesh);
}

设置组件层级关系

• 设置根组件RootComponent或者SetRootComponent()
• SetupAttachment
• AttachToComponent

RootComponent = outCollison;
SetRootComponent(outCollison);

paddle1->SetupAttachment(body, TEXT("paddle1"));
paddle2->SetupAttachment(body, TEXT("paddle2"));
paddle3->AttachToComponent(body, FAttachmentTransformRules::KeepRelativeTransform, TEXT("paddle3"));
paddle4->AttachToComponent(body, FAttachmentTransformRules::KeepRelativeTransform, TEXT("paddle4"));

childSceneComponent->AttachToComponent(root, FAttachmentTransformRules::SnapToTargetIncludingScale);

销毁组件

• DestoryComponent()
• UnregisterComponent()使用RegisterComponent创建，需要先注销再销毁

Mesh->UnregisterComponent();
Mesh->DestroyComponent();

各类组件创建与初始化

UStaticMenshComponent

paddle1 = CreateDefaultSubobject<UStaticMeshComponent>(TEXT("paddle1"));
auto paddleMesh = ConstructorHelpers::FObjectFinder<UStaticMesh>(TEXT("StaticMesh'/Game/Demo_Drone/SM/paddle.paddle'"));
if (paddleMesh.Object != nullptr)
{
	paddle1->SetStaticMesh(paddleMesh.Object);
}

UBoxComponent

outCollison = CreateDefaultSubobject<UBoxComponent>(TEXT("outCollison"));
outCollison->SetBoxExtent(FVector(60, 60, 15));
outCollison->SetSimulatePhysics(true);
outCollison->SetCollisionProfileName(TEXT("WorldDynamic"));
outCollison->SetCollisionEnabled(ECollisionEnabled::NoCollision);

USphereComponent

sphereComp = CreateDefaultSubobject<USphereComponent>(TEXT("SphereComp"));
sphereComp->InitSphereRadius(5.0f);
sphereComp->SetCollisionProfileName(TEXT("WorldDynamic"));
sphereComp->SetGenerateOverlapEvents(true);
sphereComp->OnComponentBeginOverlap.AddDynamic(this, &Amissile::Overlaphandler);

// overlap 函数绑定
void Amissile::Overlaphandler(UPrimitiveComponent* OverlappedComponent,
				AActor* OtherActor, 
				UPrimitiveComponent* OtherComp,
				int32 OtherBodyIndex,
				bool bFromSweep,
				const FHitResult& SweepResult){}

USkeletalMeshComponent

SkeletalMeshComp = CreateDefaultSubobject<USkeletalMeshComponent>(TEXT("SkeletalMeshComp"));
SkeletalMeshComp->SetGenerateOverlapEvents(true);
SkeletalMeshComp->SetSimulatePhysics(true);

USpringArmComponent和UCameraComponent

springArmComp = CreateDefaultSubobject<USpringArmComponent>(TEXT("SpringArm"));
springArmComp->SetupAttachment(RootComponent);
cameraComp = CreateDefaultSubobject<UCameraComponent>(TEXT("Camera"));
cameraComp->SetupAttachment(springArmComp);

UPhysicsThrusterComponent

upThrusterComp = CreateDefaultSubobject<UPhysicsThrusterComponent>(TEXT("upThrusterComp"));
upThrusterComp->SetupAttachment(RootComponent);
upThrusterComp->SetWorldRotation(UKismetMathLibrary::MakeRotFromX(FVector(-this->GetActorUpVector())));
upThrusterComp->ThrustStrength = 980.0f;
upThrusterComp->SetAutoActivate(true);

UTexRenderComponent

CountdownText = CreateDefaultSubobject<UTextRenderComponent>(TEXT("CountdownNumber"));
CountdownText->SetHorizontalAlignment(EHTA_Center);
CountdownText->SetWorldSize(150.0f);
CountdownText->AttachTo(RootComponent);
CountdownTime = 3;
CountdownText->SetText(FString::FromInt(FMath::Max(CountdownTime, 0)));

UProjectileMovementComponent

projectileMovementComp = CreateDefaultSubobject<UProjectileMovementComponent>(TEXT("projectileMovement"));
projectileMovementComp->InitialSpeed = 500.0f;