The new motion tweening of symbols - awkward - what am i doing wrong?

Question

Hello.
I have been doing classic tween animations for years now, and i still have to find a use for the new one to get benefits of these custom easing like "spring" etc which would be very handy to have without doing them manually. But as soon as i say to myself "ok lets try this new tweening" im running into absurds like the one on screenshot. Its a simple animation of symbol from left to right with added "spring" easing... as you can see its nothing like the one shown on the preview... Whats wrong with this? Does it need ot have like bazylion of frames to be able to work properly? And why its cutted on top so it doesnt look like elastic spring but rather like somehting hitting hard wall?

Answer 1

Agreed that the motion editor is unintuitive and generally not very good.
The issue you are running into here is this: When you apply an ease, flash does not expect you to want to ease between those two keyframes. That would be what you expect to happen, and that would be useful, but it's not the way it works. It is actually using the entire motion tween to decide how it's going to perform the ease. It's kind of difficult to describe, so maybe these screenshots will help illustrate what's going on.
In this shot, the entire length of the tween contains two keyframes. One is the start, and the other is the max height of the spring.
Everything is ruined if I duplicate the last keyframe. The expectation would be that the spring would apply between the first two keyframes, but it actually tweens the whole span.
You can sort of get an idea of what's going on as you slide those keyframes together.
If you split the motion, it will work as expected... sort of. Not sure about others, but it causes issues in our code if a movieclip's tween is not unbroken. So the whole motion editor is pretty worthless to me, and I wind up making a ton of keyframes by hand instead.