[Open Beta] Procedural On-the-Fly Animation in UE4: iTween!

[JaredTherriault]

Hey everyone, sorry for being late. Extremely late. My girlfriend and I have wanted to take a euro trip for a while and we decided to finally do it. I’ve been gone much of the summer! But now I’m back, to tween with y’all.

@;554268

I have error with packaging … Can you help me ? Thanks !

Sure , what’s the problem? Can you provide a stack trace, error logs or output? Preferably everything?

@SONB;558600

Hi !

Is it possible to change the End Value of a Float From/To tween on the fly, while this tween is already running?

is what I’m trying to do:

Distance Of Selected Step changes later and the End Value of the tween must be updated with it, when I call the function again.

When I test it and try to update the value on the fly while it is already running, it just jumps to the new value, without interpolating to it.
If it’s possible, what did I miss?

Or can I just start the tween again, like I did the first time? Because it works fine this way. If I do start the tween again and again while it’s running, is it internally reused or duplicated?

You can pull out of the return value of any tween event and set ValueTo directly that way, but it will change the interpolation so that the tween interpolates between the original start value and new end value. If the new end value is too “distant” from the original end value it will appear to jump.

What you’re doing is probably ok as long as you don’t see any adverse effects. The tweens automatically destroy themselves when their timers complete, so starting a new one is fine, especially in the case of value tweens since they’ll happen after the first tween every tick and just overwrite the first’s values. There are definitely “safer” alternatives however:

-You can start an interim tween with the start value being the original tween’s original end value and the end value of the interim tween being the new end value you want. Then set the end value of the original tween to be this new interpolated value from the interim tween. Make it run for as many seconds as are left in the original tween. You can get this amount with this pseudo-equation: OriginalNumberOfSeconds * (1.0 - Alpha (“Alpha” is a property on the original tween)). This will give you the number of seconds you have left in the original tween. This is probably the smoothest and safest solution, though a bit convoluted/messy.
-You can call StopTweenByName on the current tween then start it over with the new start value being the current value and the new end value being whatever you want it to be. Since you’re doing linear easing there should be nothing weird or jarring. This is basically what you’re already doing with an extra step to ensure no overlap.

I’m going to have some time today to look into the spline easing issue as well. I’m gonna figure out this dilemma.

@geordie;561746

Okay thankfully I was able to fix - seemed to have been due to there not being a pawn for the player controller when spawning the event actor.

Changed UiTween.SpawnEvent() so that if GetWorldLocal()->GetFirstPlayerController()->GetPawn() is null then it reverts to the old behaviour of just spawning at world origin.

That’s a bug on my end! I guess it didn’t occur to me that there would be situations where you’d use iTween and not have a possessed pawn. Totally my fault.

I switched from World Origin to accommodate large world games for the sake of memory management and preempting the possibility of a tween getting “culled” and not working. I’ll use another object for this attachment. Thank you for finding this bug!

Regarding the earlier points with compiling on xcode, I put in some platform checks for the very latest versions of iTween that should compile without issue. Are you using the very latest version? If so then I have more work to do.

@.Powell;576501

Hi ,

iTween seems really awesome but even though you’re giving it away for free we can’t use it in commercial products unless you are able to give a license.txt with it. Even a Creative Commons license would be fine: CC SA 1.0 Deed | ShareAlike 1.0 Generic | Creative Commons

Thanks!

Hi , I’d never considered this either. I think I started working on working out exactly what i was going to do vis a vis (free) licensing but to be frank it’s not as interesting as programming the thing I’ll take a look at your link later and try to figure something out. The stop-gap is that the easing equations are taken directly from another source with its own license in turn, so i have to figure out exactly what they require in their license before working out my own. All of the rest of the code however is original, so that’s the only thing I really need to consider. I will get back to you!