Chapter 15

Other Technical Issues

This penultimate chapter brings together a few topics that you may need to consider if you are going to build more complex simulations. When building such simulations there are likely to be other considerations besides just the physics. Specifically, this chapter focuses on issues that crop up in the following common scenarios: if you are building simulations in 3D, if you want your simulation to be a “scale model” of a real system, or if accuracy is particularly important.

Topics covered in this chapter include these:

• Doing physics in 3D: This section discusses how to extend our framework to create 3D simulations. In the process we’ll cover some 3D vector and matrix math and associated ActionScript 3.0 classes that will help to handle rigid body rotations in 3D.
• Building scale models: This section discusses how to choose units and parameter values to create a scale model of the system you are trying to simulate.
• Building accurate simulations: This section reviews some of the factors you need to take into account if you want to create a simulation that needs to be highly accurate.

Because 3D physics is probably what you are likely to be most interested in, we devote the major part of the chapter to doing that. Please note that the focus will be very much on doing physics in 3D, rather than on 3D programming in general. Thus, although we’ll inevitably have to discuss some aspects of 3D coding in Flash, this chapter is not about the latest cutting-edge 3D technology. Flash 3D is a huge subject in itself; there are now a multitude of 3D engines in ActionScript that can do very powerful things, and Adobe’s upcoming Stage3D will revolutionize the way we do 3D in Flash. But these topics are really outside the scope of this book. We’ll take a much more “primitive” approach here, giving you a good basic understanding of how to program physics in 3D that will help you, regardless of whether you use one of the more advanced frameworks or not.