Easing

Frames with motion tween play at a constant speed, but for more realistic animation you will certainly have to make the speed of objects more dynamic. This can be done by using more keyframes, but that is very time consuming. That is why Giotto has easing option. If you want to create the effect of acceleration and deceleration, you can use the easing option.
easing

How to enable Easing

To use easing you need to have created motion tween. Then you have to click anywhere on the tween (purple time strip). Now take a look on the Object properties window – Easing button is now active. Click on it to open the Easing dialog window.

Using Easing options

easing
As you can see from the picture above, easing options window is in form of a graph. X Axis represents the number of tweened frames, and Y Axis the percentage of animated movement or the percentage of the animated journey of the object. When the line is straight diagonal animation will play with constant speed. If you want to change the speed just left click on one of the black dots on the line and drag. Instead of a straight line you will get a curve. You can see our examples below. When the curve is moved up and left, the animation will decelerate (as shown on the picture below). You can see that the curve tells us that the 50% of the whole animation will happen in only 4 frames. The other 50% will be spread over the rest 20 frames. This will give us the impression that the animated object started to move very quickly and then decreased its speed. Of course, it is up to you to decide what will be the rate of decelerating by setting the curve appropriate for your needs. The same principle is used for acceleration; if the curve is moved down and right, the motion tween will accelerate. When you are satisfied with the curve click OK button and the easing option will be applied to your animation. If you want to remove or just start over, click Reset button and the curve will become straight again.
easing