How to clear timeline curves to reuse the timeline component?

Development Programming & Scripting C++
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1

I’m using UE4.27

Hi! In my project I have a timeline component that I want to reuse for different purposes instead of creating a bunch of different timeline components which seems unnecessary. The problem I’m having though is that there doesn’t seem to be a way to clear the curves of the timeline once you’ve added one like so:

MyTimeLine->AddInterpFloat(MyCurve, TimelineUpdate);

Now, if I add a new InterpFloat, say, something like:

MyTimeLine->AddInterpFloat(MyCurve, AnotherTimelineUpdate);

From what I understand, now this value inside the timeline component:

TArray<struct FTimelineFloatTrack> InterpFloats;

Has two elements. And when I run the timeline it will run the function attached to the FOnTimelineFloat InterpFunc; that’s inside each struct, that is, I’m running two different InterpFuncs at the same time.

How come I can’t clear this array, or remove one of its elements? It’s entirely possible I might be missing something obvious though.

Thanks!

2

Quick update: I tried to do something different but now I have a different problem:

I AddInterpFloat to the BeginPlay function. Which only adds one element to the array.

Then my idea is to rebind the delegate instead:

Have these in my header:

FOnTimelineFloat TimelineUpdate;
FOnTimelineEvent TimelineFinished;

And in my .cpp BeginPlay I have:

MyTimeLine->AddInterpFloat(MyCurve, TimelineUpdate);
MyTimeLine->SetTimelineFinishedFunc(TimelineFinished);

And I have this one in a later place in my code:

TimelineUpdate.BindDynamic(this, &AEntity::Callback_TimelineUpdate);

TimelineFinished.BindDynamic(this, &AEntity::Callback_TimelineFinished);

And in another place I have:

TimelineUpdate.BindDynamic(this, &AEntity::Callback_AnotherTimelineUpdate);

TimelineFinished.BindDynamic(this, &AEntity::Callback_AnotherTimelineFinished);

Now the problem I’m having is that the delegate doesn’t seem to bind, not even on the first one. Nothing happens when the timeline is called. I’m confused. I have tried calling unbind to see if it makes a difference, it doesn’t.

EDIT: Ok, just did a test and the delegates are bound but they are not being run when the timeline is playing.

3

Another update: I noticed that if I bind the delegates before the AddInterpFloat (in the BeginPlay), then it works for that binding. But the timeline doesn’t respond to rebinding the delegates later. Is this a bug?

EDIT: In fact, even when the delegate is unbound after being set, the timeline still runs the function that should not be bound anymore.

1 Like
4

I managed to work around the problem by using a seperate delegate.

Like this:

Put these in the header:

	// Timeline Variables
	FOnTimelineFloat TimelineFloat;
	FOnTimelineEvent TimelineFinished;

Then create these:

DECLARE_DYNAMIC_DELEGATE_OneParam(FOnTimeLineUpdate, float, PAlpha);

....

FOnTimeLineUpdate OnTimeLineUpdate;

In BeginPlay, do this:

TimelineFloat.BindDynamic(this, &AEntity::Callback_OnTimeLineUpdate);
TimelineFinished.BindDynamic(this, &AEntity::Callback_OnTimelineFinished);
		
MyTimeLine->AddInterpFloat(MyCurve, TimelineFloat);
MyTimeLine->SetTimelineFinishedFunc(TimelineFinished);

Then, you hook up the new seperate delegate like this:

OnTimeLineUpdate.BindDynamic(this, &AEntity::Callback_OneTimelineUpdate);

Then when the timeline runs, it calls the original delegate, which reroutes like this:

void AEntity::Callback_OnTimeLineUpdate(float PAlpha)
{
	if (OnTimeLineUpdate.IsBound())
	{
		OnTimeLineUpdate.Execute(PAlpha);
	}
}

It’s a very roundabout way of doing it but it seems to work.