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6 Actor

047 SetActorLocation

蓝图中的 BeginPlay 先于 C++ 代码中的 BeginPlay 执行

Item.cpp
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void AItem::BeginPlay()
{
    Super::BeginPlay();

    UWorld* World = GetWorld();

    SetActorLocation(FVector(0.f, 0.f, 50.f));
    FVector Location = GetActorLocation();
    FVector Forward = GetActorForwardVector();

    DRAW_SPHERE(Location);
    DRAW_VECTOR(Location, Location + Forward * 100.f);
}

048 SetActorRotation

Item.cpp
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void AItem::BeginPlay()
{
    Super::BeginPlay();

    UWorld* World = GetWorld();

    SetActorLocation(FVector(0.f, 0.f, 50.f));
    SetActorRotation(FRotator(0.f, 45.f, 0.f));
    FVector Location = GetActorLocation();
    FVector Forward = GetActorForwardVector();

    DRAW_SPHERE(Location);
    DRAW_VECTOR(Location, Location + Forward * 100.f);
}

049 Actor World Offset

Item.cpp
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void AItem::Tick(float DeltaTime)
{
    Super::Tick(DeltaTime);

    float MovementRate = 50.f;
    float RotationRate = 45.f;

    AddActorWorldOffset(FVector(MovementRate * DeltaTime, 0.f, 0.f));
    AddActorWorldRotation(FRotator(0.f, RotationRate * DeltaTime, 0.f));
    DRAW_SPHERE_SINGLE_FRAME(GetActorLocation());
    DRAW_VECTOR_SINGLE_FRAME(GetActorLocation(), GetActorLocation() + GetActorForwardVector() * 100.f);
}

051 The Sine Function

Item.h
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class SLASH_API AItem : public AActor
{
private:
    float RunningTime;
    float Amplitude = 0.25f;
    float TimeConstant = 5.f;
};
Item.cpp
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void AItem::Tick(float DeltaTime)
{
    Super::Tick(DeltaTime);

    RunningTime += DeltaTime;

    float DeltaZ = Amplitude * FMath::Sin(RunningTime * TimeConstant);

    AddActorWorldOffset(FVector(0.f, 0.f, DeltaZ));

    DRAW_SPHERE_SINGLE_FRAME(GetActorLocation());
    DRAW_VECTOR_SINGLE_FRAME(GetActorLocation(), GetActorLocation() + GetActorForwardVector() * 100.f);
}

052 Exposing Variables to Blueprint

  1. EditDefaultsOnly：只能在蓝图的细节面板中编辑
  2. EditInstanceOnly：只能在蓝图实例中编辑
  3. EditAnywhere：在蓝图和蓝图实例中都能编辑

053 Visible, But Not Editable

  1. VisibleDefaultsOnly：只能在蓝图的细节面板中查看
  2. VisibleInstanceOnly：只能在蓝图实例中查看
  3. VisibleAnywhere：在蓝图和蓝图实例中都能查看

054 Exposing Variables to the Event Graph

  1. BlueprintReadOnly：可以在事件图表中 get
  2. BlueprintReadWrite：可以在事件图表中 get 和 set

当变量为 private 时，meta = (AllowPrivateAccess = "true") 可以让事件图表获得操作该变量的权限

055 Exposing Functions

  1. BlueprintCallable：可以在事件图表中调用
  2. BlueprintPure：事件图表中调用此函数的节点不会有输入引脚
Item.h
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class SLASH_API AItem : public AActor
{
protected:
    virtual void BeginPlay() override;

    UPROPERTY(EditAnywhere, BlueprintReadOnly, Category = "Sine Parameters")
    float Amplitude = 0.25f;
    UPROPERTY(EditAnywhere, BlueprintReadOnly, Category = "Sine Parameters")
    float TimeConstant = 5.f;

    UFUNCTION(BlueprintPure)
    float TransformedSin();
    UFUNCTION(BlueprintPure)
    float TransformedCos();
private:
    UPROPERTY(VisibleAnywhere, BlueprintReadOnly, meta = (AllowPrivateAccess = "true"))
    float RunningTime;
};
Item.cpp
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float AItem::TransformedSin()
{
    return Amplitude * FMath::Sin(RunningTime * TimeConstant);
}

float AItem::TransformedCos()
{
    return Amplitude * FMath::Cos(RunningTime * TimeConstant);
}

056 Template Functions

057 Components

058 Components in C++

Item.h
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class SLASH_API AItem : public AActor
{
private:
    UPROPERTY(VisibleAnywhere)
    UStaticMeshComponent* ItemMesh;
}
Item.cpp
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AItem::AItem()
{
    PrimaryActorTick.bCanEverTick = true;

    ItemMesh = CreateDefaultSubobject<UStaticMeshComponent>(TEXT("ItemMeshComponent"));
    SetRootComponent(ItemMesh);
}

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