Game Programming: Action-Oriented AI
- On Action Games
- Choreographed AIs
- Object Tracking
- Hiding and Taking Cover
- Putting It All Together
- In Closing
"Action may not always bring happiness; but there is no happiness without
Now that we have a global understanding of the building blocks of any AI system, it is time to delve into the details of how AI is built into video games. Because this is a lengthy subject, with different techniques used for different gameplay styles, I have divided the information into three separate chapters. Most game AI techniques might not be very complex, but there are many twists and interesting ideas to which we will have to devote some space.
In this chapter, I will provide an overview of AI methods used in fast-paced action games. We will review general techniques, and then do a case-by-case analysis on fighting games, racing simulators, and so on, providing insider information on many popular algorithms.
The next chapter will deal with the subject of tactical AI, which finds its main use in strategy games. We will learn to build plans, analyze enemy configurations, and trace maneuvers that would marvel most real-world generals.
We will end our journey through artificial intelligence techniques with a chapter on scripting, which is one of the most powerful paradigms for coding AIs. By separating the AI code from the main game engine, scripting provides a robust and flexible way of creating large AI systems. In fact, most professional AIs today are built via some sort of scripting engine. So we will analyze the different scripting techniques in detail.
Let's begin with the basics. We need to create little creatures that chase us and shoot, so let's get to work.
On Action Games
For this book, I will define action as intelligent activity that involves changes of behavior at a fast speed. Examples of action are all locomotion behaviors (a character that runs in Mario), simple aggression or defense (enemies shooting or ducking in Quake), and so on. Notice how action is put in a contraposition to tactical reasoning, which is in turn described as the analysis process used to create a plan that will then guide the actions of an intelligent character. So, action deals with immediate activity, and tactics plan that activity.
Action is thus driven by relatively simple tests. We will need to compute distances to targets, angular separations, and so on. Action is also quite fast-paced. Action games have higher rhythms than tactic/strategic games.