An Introduction to Expressions

Expressions are the essential component of a special kind of animation known as procedural animation. (You’ll see this same sentiment expressed again in Chapter 15, “Animation with Expressions;” as they say, repetition is the key to comprehension.) As the name suggests, this method of animation uses mathematical procedures to produce the motion, rotation, and all other applicable parameters of modification to your objects.

At first glance, expressions can seem quite daunting. Because they give you the freedom to do almost anything, there are usually several ways to accomplish any one goal. Consequently, learning to use expressions can get a little overwhelming. What you will find with experience, though, is that certain patterns often recur in your use of expressions that will help you to break them down into more manageable chunks.