Reset lastFrameAdvance after an AnimationAction.jumpTo

[solarized-fox]

I noticed that the frame some of my animations started on seemed somewhat random, even after calling Sprite.jumpToFirstFrame. after doing some digging, I believe this code is the culprit. it seems the way animations in indigo work is that a timestamp is saved each time a frame advances, and when the time since that timestamp is greater than the current frame's designated duration, it flips to the next frame

if so, reusing the lastFrameAdvance value here seems incorrect. for example, if you call Sprite.jumpToFirstFrame midway through frame n, it will effectively jump to midway through frame 0 rather than the beginning, which I don't think is the expected effect. using the current time instead seems to fix the issue I was having, but it's possible there's an intentional design choice I'm not aware of, so feel free to use your discretion here

[davesmith00000]

I think I've seen this myself very occasionally - I suspect I just don't use sprite animations very often / in this way so the bug hasn't struck me as being a big thing. But I think you're probably right and it would be great to get it resolved!

What I don't know without working on it, is whether or not this is the right fix.

Do you think you could try and write a unit test that shows and then fixes the issue? There is already an AnimationRefTests test suite you could make use of.

[solarized-fox]

@davesmith00000 yeah I noticed it because a jump animation I'm using had two frames which gave it the appearance of having random playback haha. it's late here but I will look into writing unit tests tomorrow, I wanted to be sure my hypothesis wasn't way off base before I put the time into writing tests. thanks for the tip on the AnimationRef test suite, that'll make things a lot easier than I was anticipating 👍

[solarized-fox]

alright, I wrote up a test that demonstrates the problem. this should pass on this branch, but if you check this file out on main it will fail on line 107