Chapter 13: Forward Kinematics--Making Things Walk

Overview

What well cover in this chapter:

• Introducing forward and inverse kinematics

• Getting started programming forward kinematics

• Automating the process

• Making it really walk

Up to now, youve been going down a particular path , and it has all flowed very nicely . In fact, the previous chapters covered just about all the basics of interactive ActionScripted animation, even all the very advanced basics. Now, Im going to branch off to some other interesting techniques that use kinematics.

So, what exactly is this thing called kinematics ? It always seemed kind of scary when I tried to find out about it. I know its built into some advanced 3D animation programs, and if you look it up online, youll find some pages that will barrage you with strange symbols in equations that make anything youve done so far in this book look like first-grade arithmetic. So, first, I want to say that its really not that tough. The previous chapters covered just about all the concepts you need. You just have to put them together in the right way.

Kinematics is basically the branch of mathematics that deals with the motion of objects without regard for force or mass. So, its speed, direction, and velocity. Sounds pretty basic, eh? Well, thats a pretty simple definition, and Im sure it gets into some complex stuff, but for our purposes, yeah, thats pretty much it.

When people in computer science, graphics, games , and so on start talking about kinematics, they are talking about two specific branches of kinematics: forward kinematics and inverse kinematics. Lets start there.