LinkedAnimGraphs within a LinkedAnimClassLayer not being removed when calling UnlinkAnimClassLayer

Development Character & Animation
1

(On 4.27)

Every time my characters switch weapons, they unlink the old weapon’s set of AnimClassLayers and link in the new weapon’s set of AnimClassLayers, via UnlinkAnimClassLayers(Class) and LinkAnimClassLayers(Class) respectively.

However I found that LinkedAnimGraphs that some of those AnimClassLayers might utilize are not successfully unlinked, and linger on the USkeletalMeshComponent, and are there to stay.

After switching weapons a bunch of times, the list logged by this code

	if (const USkeletalMeshComponent* SkelMeshComp = GetSkelMeshComponent())
	{
		for (auto It = SkelMeshComp->GetLinkedAnimInstances().CreateConstIterator(); It; ++It)
		{
			const UAnimInstance* LinkedAnimInstance = *It;
			UE_LOG(LogTemp, Display, TEXT("Linked anim instance is: %s"), *GetNameSafe(LinkedAnimInstance))
		}
	}

… becomes really big, bringing down my FPS, as shown by UnrealInsights:

1455×248 33.5 KB

Is linking and unlinking anim class layers when switching weapons no longer a valid usecase? Or is that I’m not supposed to be using LinkedAnimGraphs within those class layers? And if this is a valid usecase of both, what’s the best way to clear out those lingering LinkedAnimGraphs via C++?

Thanks for the help!

2

For future seekers, this bit of code (being called from the master AnimInstance) seems to have solved the issue

	// Linked instances like to linger in our skeletal mesh unless we destroy them manually
	if (USkeletalMeshComponent* SkelMeshComp = GetSkelMeshComponent())
	{
		// ... so do just that (ClearAnimScriptInstance will internally call ResetLinkedAnimInstances which is what we're really after...)
		SkelMeshComp->ClearAnimScriptInstance();

		// ...but this nullifies ourselves as the master anim instance, so undo that side effect
		SkelMeshComp->SetAnimInstanceClass(GetClass());
		SkelMeshComp->AnimScriptInstance = this;
	}

It’s not ideal, it feels wrong (especially considering the fact that ResetLinkedAnimInstances is a private member of USkeletalMeshComponent and we’re hacking our way into calling it) but it oddly seems to be the only way to work around this bug?

2 Likes
3

I’m looking for a solution for this too. Did you ever find a better solution to this?

4

Anyone with an answer to this? Any suggestions would be really appreciated.