AttachToComponent not working

Development Programming & Scripting
1

I am trying to attach an actor to a component of the player but it is not working… Any suggestions?

void ABasePlayer::PickupItem(APickupItem * const item)
{
  //Call the on pickup method of the item. This is called before the attachment to component method is because
  //if physics are being simulated, then the physics object loses its parents.
  item->OnPickupItem();
  //Attach item to items component.
  item->AttachToComponent(equippedItemComponent, FAttachmentTransformRules::SnapToTargetNotIncludingScale, NAME_None);
}
2

I don’t understand
//if physics are being simulated, then the physics object loses its parents.

you should disable physics before attaching to the other component.

other question would be
equippedItemComponent is definitely not a nullptr?

3

Physics sim is stopped when the OnPickupItem() method is called.

void APickupItem::OnPickupItem()
{
	staticMesh->SetSimulatePhysics(false);
	staticMesh->SetCollisionResponseToAllChannels(ECollisionResponse::ECR_Overlap);
}

Also equippedItemComponent is not null since before this function is called, it is initialized in BeginPlay

equippedItemComponent = CreateDefaultSubobject<USceneComponent>(TEXT("EquippedItemComponent"));
  equippedItemComponent->SetupAttachment(RootComponent);
4

The hierarchy is like this:
RootComponent->staticMesh
So staticMesh is not the root.

5

staticMesh is the root of the APickupItem?

6

isn’t that already a problem?
if I remember correctly when we tried to simulate a non root component it kind of feels like it’s detached from the root component (moves independently of the actual actor),

what I would expect to happen is:

  • Simulating physics on the non root component leads to it getting moved away from the original distance to its root component
  • Stopping simulating physics freezes that new distance to the root component
  • Attaching the root component with snap to target moves the root component to the target location
  • The static mesh moves to keep the relative distance to the root it had, at the time when you stopped physics simulation.
7

Ah OK, I didn’t know that’s what really happened. I thought that it dragged the whole actor with it… Thanks for the answer, I managed to fix the problem like you said… Made staticMesh my RootComponent.