Slow In and Slow Out
From Anipedia
Information below from: Tutorial:Motion_tweening
[edit] Easing and the Ease In/Ease Out Graph
A default tween equates the same distance of motion from one frame to another. The idea of easing is to start a tween by making one end of the tween faster or slower than the other, resulting in smoother and more believable motion. The ease tool is found in the Properties window - the same place you did your full clockwise rotation.
After you set the easing bar either way, watch your animation by pressing "Enter" or going to Control > Test Movie, and notice how it will change the speed of the tween.
Easing allowed for some control of the speed of a tween, but it is very limited compared to the Graph Editor. Right next to to the easing tool is a button that says "Edit...". With the tween selected, click this button and the Graph Editor window will appear. Flash calls this the Custom Ease In/Ease Out window.
Take a look at the animations with their coinciding graphs:
|
No Easing |
Slow In 100% |
Slow Out 100% |
 |
 |
 |
===Control points=== As you can see at the beginning and end of each graph their is a black dot. This is a control point. The graph editor can support multiple control points at any point in the graph. Each control point, when selected, has two manipulator handles. If you drag one it drags the other along with it. It controls the curve for that point. This is useful for complicated tweens that may demonstrate, for example, an object being affected by gravity, like a bouncing ball. The only thing in the graph you cannot change is that it must have a minimum of two points (beginning and end), and those points must remain at 0% and 100%, respectively.
In the below images you will learn how to add another control point and how to manipulate it.
This animation was made using the graph beneath it:
My beginning and end control points have steeper curves than the easing slider can make, so if you are not satisfied with the ease sliders, remember that you can edit them in the graph editor, right next to the slider on the Edit... button.
Keep in mind though that if two tweens are sitting next to eachother and one of them has easing, the other one has to match the incoming speed of the other tween, otherwise you will get a strong sudden slowing down or speeding up effect. For example, if you end a tween on a 5% animation speed per frame, the next tween should be coming in at 5% per frame as well for a smooth transition. Sometimes flash will do this automatically for you. An easy and fairly accurate way to do this is to measure where your manipulators are based on points on the graph.
