Using UniversalTweenEngine with LibGDX music - libgdx

Question

Short question...
How do I correctly use UniversalTweenEngine with the Music class in LibGDX?
Long question...
I've encountered a problem with using UniversalTweenEngine and the Music class in LibGDX. I have a MusicAccessor that implements TweenAccessor like so:
public static final int VOLUME = 0;
#Override
public int getValues(Music target, int tweenType, float[] returnValues) {
switch(tweenType) {
case VOLUME:
returnValues[0] = target.getVolume();
return 1;
default:
assert false;
return -1;
}
}
#Override
public void setValues(Music target, int tweenType, float[] newValues) {
switch(tweenType) {
case VOLUME:
target.setVolume(newValues[0]);
break;
default:
assert false;
}
}
first I used it like this:
Tween.registerAccessor(Music.class, new MusicAccessor());
myMusicInstance.setVolume(0);
Tween.to(myMusicInstance, MusicAccessor.VOLUME, 1f).target(1).start();
Which gave me an error saying that
No TweenAccessor was found for the target
I read some on the problem and saw people having the same issue, and the answer to this question told me that I had to use .cast(Music.class) as well, so i changed it to this:
Tween.to(myMusicInstance, MusicAccessor.VOLUME, 1f).cast(Music.class).target(1).start();
which no longer gives me the error. The snag with this is that it doesn't actually tween any value! I've added TweenCallbacks and done System.out.println("text") in the TweenAccessor's methods, and found out that they aren't being called. So how am I supposed to do for it to work?

Answer 1

I reproduced your problem and managed to fix it, so here is a solution.
First of all you need an instance of TweenManager. Then don't forget to start your music (it won't start by itself). Your MusicAccessor class is ok, so no need to change anything there. The final code snippet:
an instance field
private TweenManager tweenManager = new TweenManager();
constructor (or wherever you used it)
Tween.registerAccessor(Music.class, new MusicAccessor());
myMusicInstance.setVolume(0);
myMusicInstance.play();
and then in render:
tweenManager.update(delta);
Tween.to(music, MusicAccessor.VOLUME, 1f).cast(Music.class).target(1).start(tweenManager);
If anything is unclear, please let me know.