Learning ActionScript 3.0

Chapter 7. MOTION

From your very first experiment to the umpteenth time you’ve performed a familiar task, moving assets with code can be a gratifying experience. In addition to creating more dynamic work by freeing yourself from the permanency of the timeline, there is something very immediate and pleasing about controlling the motion of a symbol instance purely with ActionScript.

Because programming motion can cover a large number of concepts, we’ve chosen a few as the main focus areas for this subject. In each area, we offer what we call simplified simulations—that is, we do not maintain that our examples accurately reflect real-world scenarios. We won’t be accounting for every possible force that can act on an object in each sample file. On the contrary, we try to present approaches to each topic that are simple enough to integrate into your projects with ease.

In addition to simplifying some topics, we also hope to show that math can be your friend. To some of you, this is a given, but to others, having to deal with numbers is an uphill journey. If you find yourself in the latter category, we hope to smooth over some of the smaller bumps that might be caused by a knee-jerk reaction to the need for math. Understanding just a few small applications of mathematical or scientific principles can really go a long way. You may even find yourself becoming comfortable with these principles and applying them even when there are other ways to accomplish a goal.

In this chapter, we’ll look ...