CHAPTER 17
COLLISION AND SIMPLE PHYSICS

by Mike McShaffry

Even the simplest 2D game needs collision. After all, if the objects in a game can’t interact, how fun could the game possibly be? Breakout is a great example of a simple game. A ball bounces off walls, bricks, and the paddle. If you look at it this way, the core of the game experience is created by the 2D collision algorithm. It’s almost impossible to design a game without at least some rudimentary collision. Perhaps a text adventure like Zork is one example, but hey, it hasn’t exactly been flying off the shelves lately. If you are familiar with Zork, that’s great because you know your game history. If you’ve actually played Zork, well, then you are probably as “mature” as I am.

Collision is a purely mathematical calculation to determine the spatial relationship between objects such as points, lines, planes, or polygonal models. I’ll point you to some great resources outside of this book that provide good solutions. I’m not going to pretend I can offer something better.