Custom Instance Data per Level Sequence Actor

This is very useful if you want to have custom per instance data, by default UE has a default instance data class which allows you to override the world origin of your sequence your are playing.

Warning

The TransformOrigin doesn’t handle scale.

Simple raw implementation:

// Most of the spawning and initializing parts are from the sequencer BP function library.
FActorSpawnParameters SpawnParams;
	SpawnParams.SpawnCollisionHandlingOverride = ESpawnActorCollisionHandlingMethod::AlwaysSpawn;
	SpawnParams.ObjectFlags |= RF_Transient;
	SpawnParams.bAllowDuringConstructionScript = true;
	
	// Defer construction for autoplay so that BeginPlay() is called
	SpawnParams.bDeferConstruction = true;
	
	LevelSequenceActor = GetWorld()->SpawnActor<ALevelSequenceActor>(SpawnParams);
	
	FMovieSceneSequencePlaybackSettings PlaybackSettings;
	PlaybackSettings.bAutoPlay = true;
	PlaybackSettings.PlayRate = PlayRate;
	LevelSequenceActor->PlaybackSettings = PlaybackSettings;
	LevelSequenceActor->GetSequencePlayer()->SetPlaybackSettings(PlaybackSettings);
	
	LevelSequenceActor->SetSequence(LevelSequence.LoadSynchronous());
	
	LevelSequenceActor->bOverrideInstanceData = true;
	auto* InstanceData = Cast<UDefaultLevelSequenceInstanceData>(LevelSequenceActor->DefaultInstanceData);
	// there is also an actor version
	InstanceData->TransformOrigin = GetInstanceTransform();
	
	LevelSequenceActor->InitializePlayer();
	
	FTransform DefaultTransform;
	LevelSequenceActor->FinishSpawning(DefaultTransform);
	
	LevelSequencePlayer = LevelSequenceActor->GetSequencePlayer();
	LevelSequencePlayer->OnFinished.AddUniqueDynamic(this, &ThisClass::OnSequencerFinished);

With bOverrideInstanceData true ALevelSequenceActor::GetInstanceData() (from the interface IMovieScenePlaybackClient) will return DefaultInstanceData.

The transform origin is used by FGatherTransformOrigin::Run, which uses IMovieSceneTransformOrigin with NativeGetTransformOrigin.