Chapter 22. Geometrical Algorithms

"Don't try to be like Jackie. There is only one Jackie.… Study computers instead."

Jackie Chan

KEY TOPICS

• Point Inclusion Tests

• Ray Intersection Tests

• Moving Tests

• Point Versus Triangle Set Collision (BSP-Based)

• Mesh Versus Mesh (Sweep and Prune Approach)

• Computing a Convex Hull

• Triangle Reduction

• In Closing

This chapter is devoted to providing you with a collection of useful geometrical tests for computer games. Most of it deals with the subject of collision detection and response, which is of extreme importance for almost any game. However, there are many more techniques to explore. We need to detect the room the player is standing in, compute the sound propagation, and explore a myriad of other tests we will end up using on a day-to-day basis.

The structure of this chapter is thus a bit different from the rest of the book. It is a collection of articles on different geometric computations, so it can be browsed quickly to find what you are looking for.