Unreal engine 4 - Actor not updating (when instancing on c++)?

Question

My custom actor (containing a few custom UMeshComponent) does not update when I change its location or the visibility of its components.

I instantiate it this way in StartPlay() of my GameMode class:

  MyCustomActor = GetWorld()->SpawnActor<AMyCustomActor>(AMyCustomActor::StaticClass());

Then I set its new location like this:

  MyCustomActor->SetActorLocation(FVector(100,0,0));

Is it because I did not set the Owner? Or what is wrong?

Note

I don't understand why, but my code works now... It might be linked to those warnings:

LogActor:Warning: GameSession /Game/PersistentLevel.GameSession_19 has natively added scene component(s), but none of them were set as the actor's RootComponent - picking one arbitrarily

and

LogActor:Warning: Natively added component (MyCustomActor_143.RootComponent) was left unattached from the actor's root.

Answer 1

The problem is that in the constructor of your "MyCustomActor" you need to assign a RootComponent that is a SceneComponent. Typically you will see something like a ShapeComponent (SphereComponent, CylinderComponent, etc.).

Then in the constructor, once you have a RootComponent defined in the actor, you need to attach the RootComponent to all other SceneComponents that you add to that Actor.

Constructor Example:

AMyActor::AMyActor()
{
    BoxComponent = CreateDefaultSubobject<UBoxComponent>(TEXT("BoxCollider"));
    // ... setup your box component here ...
    RootComponent = BoxComponent;

    StaticMeshComponent = CreateDefaultSubobject<UStaticMeshComponent>(TEXT("Mesh"));
    // ... setup your static mesh component here ...
    StaticMeshComponent->AttachTo( RootComponent ); // Or you could write StaticMeshComponent->AttachTo( BoxComponent );
}

By setting this as the RootComponent, and assuming your Actor is set to Movable, is active, and allowed to update, your call to SetActorLocation(FVector(100, 0, 0)); will move your actor to that location.