Some design issues are particular to vehicle simulations and are described in the following sections. Creating the Sense of SpeedIn a flight simulation, there's little need for a sense of speed because simply flying fast is rarely the point. Most players either are trying to fly accurately and aerobatically or are engaging in aerial combat. Although speed is an important factor in the game, conveying that sense to the player isn't critical to the experience. In driving simulations, however, the sense of speed is all-important. Here are some ways to create it:
G-ForcesThe driver of any vehicle feels a variety of forces affecting her body: acceleration, deceleration, and centrifugal force. She can feel these forces as pressure driving her body in one direction or another, usually into the seat or against the belts holding her in. The forces give a lot of valuable feedback about the behavior of the vehicle. Unfortunately, in a simulator, we can't provide any of those feelings to the player, so we have to substitute other indicators. With driving simulators, it doesn't matter that much because automobiles seldom generate significant G-forces, and the player has plenty of other visual cues, as described in the previous section. Military aircraft can generate powerful G-forces, but because the player spends most of her time looking at the sky, there's nothing to indicate them. The engines of modern fighter planes are powerful enough to tear the plane apart if it is mishandled, and if you're doing a realistic simulation, you might want to include this deadly little detail. If so, you should include a G-force meter showing the amount of stress being applied to the plane (and pilot). Most aircraft are designed to sustain strong downward G-forces, but not upward ones. In addition, pilots undergoing strong downward G-forces can black out momentarily as all the blood drains out of their heads. They can also suffer an experience called redout if they encounter a strong upward G-force, as too much blood flows into their heads. Many games simulate these conditions by fading the screen to black or to red, which, in addition to preventing the player from seeing anything, gives a clear indication that something is wrong. Designing OpponentsThe easiest way to design a variety of opponents in a vehicle simulation is simply to vary the performance characteristics of their vehicles. One plane climbs slightly faster than another; one can turn more sharply. The player will experience different challenges in dealing with each one based on their design parameters. However, this kind of variety is static and, after the player has figured it out, is easily beaten. As soon as he discovers that a Supermarine Spitfire can consistently outrun a Messerschmitt BF 109 in level flight, it offers an obvious strategy for Spitfire pilots: "boom and zoom" ( hitting and running away). To create further variety in the behavior of individual opponents, the AI for those opponents should be designed around getting perfect performance from the vehicle and then creating variations from perfection . For example, it's possible to create a "perfect" AI driver in a racing simulation. He always follows the most efficient line around the track, he always shifts gears at precisely the correct moment, and he knows the ideal speed at which to take each corner without spinning out. If such a driver has a better car than the player's, he will be unbeatable. The trick, then, is to modify the AI driver's judgment so that it isn't perfect ”so that he doesn't always shift at exactly the right time or follow the most efficient line. It is the combination of factors, both vehicle characteristics and variable driver skill, that provides the variety among opponents in vehicle simulators. As you study the business of flying or driving, you will discover other tricks to incorporate into the AI: drafting behind other cars , for example, and diving out of the sun to surprise the enemy in a dogfight. Intellectual Property RightsAs a general rule, you can model and simulate military equipment without obtaining permission from their manufacturers. Because such machines are not sold to the general public, nor are generally exploited in any other way, their appearance is in the public domain. Automobiles are another story, however. If you are going to simulate an existing car and use its real name and logo, you must have a license from the manufacturer. The manufacturer might not be willing to let you show the car crumpled and burning by the side of the road, either. This accounts for the large number of vehicle simulations in which the cars can flip over in an accident but never get damaged ”they flip back upright a second or two later, as in Beetle Adventure Racing . Or, you can do as Interstate '76 did and model cars that look rather like existing vehicles and have similar names , but don't actually use the manufacturer's indicia.
|