ActionScript™ 3.0 Bible

Chapter 31. Scripting Animation

Introduction

In this chapter

• Understanding Animation

• Using Motion XML

• Animating in Flash CS3 Professional

• Animating in Flex 2

• Using Other Animation Packages

Animation is one of the serious strong points of the Flash platform. Flash evolved out of an animation tool, and it continues to be used to animate everything from web comics to popular television shows and advertisements. There has always been a big gap between using the Flash IDE to animate by hand and creating animations in ActionScript 3.0. New functionality in Flash CS3 Professional helps to bridge this gap. In addition, Flex sports its own animation framework and there are a number of freely available third‐party animation frameworks for ActionScript 3.0.

Understanding Flash Player and Animation

Intuitively, you know that animation is movement. Specifically, animation is movement achieved by sequencing individual still pictures. Your eyes and your brain conspire to interpret these separate pictures, or frames, as one fluid motion, through persistence of vision.

Frame rate

Flash Player, like all things running on a computer, displays static frames in sequence. It attempts to display these frames as fast as the frame rate of the movie, which is measured in frames per second. Motion at 30 frames per second (fps) appears fluid, but presenting even more frames per second can help—although the brain might not be able to distinguish these frames as individual pictures, their image is factored into the perception ...