AI blackboard object reference upon actor destroy

Development Programming & Scripting AI
, , , , ,
1

I would like to get clarification on the observation I noticed during my AI/BehaviorTree/Blackboard usage:

Based on my experiment, It seems that when a blackboard referenced actor (object) is destroyed externally (triggered by DestroyActor somewhere else), the said blackboard object (referencing the actor) automatically becomes un-set, without me explicitly resetting that reference to none. Is this observation correct and the intended behavior that I can rely on as “officially supported”?

Thanks!

L.

2

Any comments on this? Are black board object references “weak”?

3

The following code snippet as found from BlackboardKeyType_Object.cpp seems to confirm the speculation:

UObject* UBlackboardKeyType_Object::GetValue(const UBlackboardKeyType_Object* KeyOb, const uint8* RawData)
{
	// RawData can be NULL if the key is corrupted by bad data, such as if someone has duplicated a key in a derived
	// blackboard.  We must handle that bad data case gracefully.  It's likely that we need to handle this for
	// all blackboard key types, so possibly GetValueFromMemory should handle the NULL case instead.  But for now I'm
	// just fixing the case I came across.
	if (RawData == NULL)
	{
		return NULL;
	}

	FWeakObjectPtr WeakObjPtr = GetValueFromMemory<FWeakObjectPtr>(RawData);
	return WeakObjPtr.Get();
}

bool UBlackboardKeyType_Object::SetValue(UBlackboardKeyType_Object* KeyOb, uint8* RawData, UObject* Value)
{
	TWeakObjectPtr<UObject> WeakObjPtr(Value);
	return SetWeakObjectInMemory<UObject>(RawData, WeakObjPtr);
}