UEC++生成Actor

1、直接生成Actor

GetWorld()->SpawnActor<AActor>();

GetWorld()->SpawnActor(AActor::StaticClass());

UWorld* world = GetWorld();
world->SpawnActor<AActor>(AActor::StaticClass());

SpawnActor 在 world 类中的定义

/** Templated version of SpawnActor that allows you to specify a class type via the template type */
    template< class T >
    T* SpawnActor( const FActorSpawnParameters& SpawnParameters = FActorSpawnParameters() )
    {
        return CastChecked<T>(SpawnActor(T::StaticClass(), NULL, NULL, SpawnParameters),ECastCheckedType::NullAllowed);
    }

    /** Templated version of SpawnActor that allows you to specify location and rotation in addition to class type via the template type */
    template< class T >
    T* SpawnActor( FVector const& Location, FRotator const& Rotation, const FActorSpawnParameters& SpawnParameters = FActorSpawnParameters() )
    {
        return CastChecked<T>(SpawnActor(T::StaticClass(), &Location, &Rotation, SpawnParameters),ECastCheckedType::NullAllowed);
    }
    
    /** Templated version of SpawnActor that allows you to specify the class type via parameter while the return type is a parent class of that type */
    template< class T >
    T* SpawnActor( UClass* Class, const FActorSpawnParameters& SpawnParameters = FActorSpawnParameters() )
    {
        return CastChecked<T>(SpawnActor(Class, NULL, NULL, SpawnParameters),ECastCheckedType::NullAllowed);
    }

    /** 
     *  Templated version of SpawnActor that allows you to specify the rotation and location in addition
     *  class type via parameter while the return type is a parent class of that type 
     */
    template< class T >
    T* SpawnActor( UClass* Class, FVector const& Location, FRotator const& Rotation, const FActorSpawnParameters& SpawnParameters = FActorSpawnParameters() )
    {
        return CastChecked<T>(SpawnActor(Class, &Location, &Rotation, SpawnParameters),ECastCheckedType::NullAllowed);
    }
    /** 
     *  Templated version of SpawnActor that allows you to specify whole Transform
     *  class type via parameter while the return type is a parent class of that type 
     */
    template< class T >
    T* SpawnActor(UClass* Class, FTransform const& Transform,const FActorSpawnParameters& SpawnParameters = FActorSpawnParameters())
    {
        return CastChecked<T>(SpawnActor(Class, &Transform, SpawnParameters), ECastCheckedType::NullAllowed);
    }

2、滞后生成Actor

// 创建actor生成变换
   FTransform tran;
   // 滞后生成Actor
   AActor* actor = GetWorld()->SpawnActorDeferred<AActor>(AActor::StaticClass(), tran);
   // 确定生成对象到世界
   actor->FinishSpawning(tran);

SpawnActorDeferred 在 world 类中的定义

/**
    * Spawns given class and returns class T pointer, forcibly sets world transform (note this allows scale as well). WILL NOT run Construction Script of Blueprints 
    * to give caller an opportunity to set parameters beforehand.  Caller is responsible for invoking construction
    * manually by calling UGameplayStatics::FinishSpawningActor (see AActor::OnConstruction).
    */
   template< class T >
   T* SpawnActorDeferred(
       UClass* Class,
       FTransform const& Transform,
       AActor* Owner = nullptr,
       APawn* Instigator = nullptr,
       ESpawnActorCollisionHandlingMethod CollisionHandlingOverride = ESpawnActorCollisionHandlingMethod::Undefined
       )
   {
       if( Owner )
       {
           check(this==Owner->GetWorld());
       }
       FActorSpawnParameters SpawnInfo;
       SpawnInfo.SpawnCollisionHandlingOverride = CollisionHandlingOverride;
       SpawnInfo.Owner = Owner;
       SpawnInfo.Instigator = Instigator;
       SpawnInfo.bDeferConstruction = true;
       return (Class != nullptr) ? Cast<T>(SpawnActor(Class, &Transform, SpawnInfo)) : nullptr;
   }