   Driving game algorithms / research
  I am doing some research that I will be presenting to my game programming class and was wondering if you guys could help me. I have a few questions about the Driving genre (my topic). My class has an AI focus but we are covering other things like pathfinding and simple physics (more like cheating using heuristics to make it simpler) and graphics. I was hoping to find details (anything really) about certain games -- like Grand Theft Auto 3 I was wondering what sort of physics they used, as at the time, I think around 2001 when it came out physics was a relatively new thing. How did they make the feel of the different cars, the performance characteristics and how they handled? Also what pathfinding did they use? (what kind of behavior guided the police?) What about other games in the driving genre? Do some of the more racing type games use simple pathfinding and a combination of different simple behavior? I am very interested in any algorithm  that is being used for driving games. I really don't know any details about these games and can't find too much just searching. I don't want to speculate -- hopefully someone can enlighten me.If this is in the wrong forum please let me know.   
  Many games use some level of physics now for vehicles, and this would range from simple arcade style physics up to complex suspension models. (There is a real-time vehicle "simulation" toy/game called "Rigs of Rods" that actually models the flexible nature of the vehicle bodies to have bodies that realistically twist and deform.) I believe most physics engines come with basic vehicle models, or constraint and friction systems that are useful to create vehicle models. For example, Havok has good vehicle support built into their SDK. And Bullet has vehicle samples in its distribution.For the most part, you are not going to be able to find out how specific commercial games implement their physics or AI. The developers often consider this proprietary information, trade secrets that helps them maintain their competitive edge in the games market. That said, sometimes you can learn a little bit about each game. According to the Wikipedia page for Grand Theft Auto IV, it is using the open source Bullet engine for something (doesn't say physics or just rigid body dynamics when a car hits something for example).Pathfinding in games is often done with a variant of the so-called A* (A-star) algorithm, often in conjunction with a navigation mesh. A racing game AI might actually feed into the steering column, e.g., give an instruction "turn right" or "accelerate" rather than "move onto this path." That would give the AI-based vehicles a degree of realism...they would behave according to physics an the AI would simulate the driver. At a higher level, the particular path that the AI searches for would be like "find shortest path to the bad guy" then the driver simulation feeds steering commands that adapt to try and keep the car on the found path.I am not a racing game expert, so the above is kind of general. I did find the following article on gamasutra (free registration if you have to register):The Pure Advantage: Advanced Racing Game AIThat article might be useful to help you with your presentation. You'll notice it doesn't talk about physics. It does talk about the AI side. The AI goals feed inputs to the physics system, sort of as described above.   