Chapter 9. Animation with Motion Tweening

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Frame-by-frame animation has two drawbacks: First, it's labor- intensive ; second, it creates large files. Macromedia Flash MX offers a way to mitigate both problems with a process called tweening . In Chapter 8, you created a three-frame animation of a bouncing ball by changing the position of the ball graphic in each of the three keyframes. Then you learned how to stretch out the animation by adding in-between frames that simply repeated the contents of the preceding keyframe. With tweening, you create similar keyframes, but Flash breaks the keyframe changes into multiple steps and displays them in the in-between frames .

To tween a graphic, Flash creates a series of incremental changes to that graphic; these changes are simple enough that Flash can describe them mathematically. Flash performs two types of tweening: motion tweening and shape tweening. This chapter covers motion tweening; Chapter 10 covers shape tweening.

Both types of tweening follow the same basic pattern. You give Flash the beginning and end of the sequence by placing graphic elements in keyframes. Then you tell Flash to spread the change out over a certain number of steps by placing that number of frames between the keyframes. Flash creates a series of images with incremental changes that accomplish the action in the desired number of frames.

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