The Presentation Layer

The presentation layer of a vehicle simulator is chiefly concerned with creating the visual and auditory appearance of being in the vehicle itself, so management activities are kept to a minimum. When there are different gameplay modes at all, they usually offer the player a new perspective rather than a different set of challenges. The major exception is serious racing games, which generally provide a variety of camera angles while driving, but also a number of customization and tuning modes for modifying the car in the workshop.

Interaction Model

The interaction model in a vehicle simulator is normally quite straightforward: The player’s vehicle is his avatar. The machine’s controls are mapped onto the computer’s input devices, and the player’s view is normally that of the pilot or driver, forward through the cockpit windows. However, games that include an avatar character who drives the vehicle, such as in Halo and other shooters, are an exception. In sports that involve the driver doing tricks with the vehicle, such as motocross, the vehicle is steered with one set of buttons, and the avatar controlled (for trick combos) with another set. You will have to spend some time working out the ergonomics of being able to control a vehicle while doing the tricks combos. As always, play-testing is crucial to getting this right.

Camera Model

The camera model in most vehicle simulations doesn’t try to be intelligent; it just offers a variety of fixed perspectives from different angles. Although the game cannot be played from all of these angles, the unplayable angles can be used for taking dramatic screenshots or for viewing instant replays of the action.

Views Common to Driving and Flight Simulators

Both driving and flight simulators implement certain standard views:

• Pilot’s/driver’s view. This is the normal view that most simulators offer by default. The player sees what the pilot would see from the cockpit or what the driver would see from the driver’s seat. The vehicle’s instruments take up the lower half of the screen, and the upper half shows the view out of the windshield, often partially obscured by parts of the hood or the nose of the plane. Most sims offer separate look-left, look-right, and look-backward views, as well as a mode in which the player can swivel the view smoothly in all directions to see what’s overhead and down to see instruments located below the pilot’s normal line of sight.

• Cockpit-removed view. This unrealistic but dramatic viewpoint uses the full screen to show the pilot or driver’s view out of the front of the vehicle, unobscured by the cockpit controls. Semitransparent overlays in the corners of the screen allow the player to see instrument readings without much interference with the view. Even these overlays can be removed, providing an unobscured view of the world outside with no visible indication that the player is in a vehicle at all.

• Chase view. This is an exterior view of the player’s vehicle, as if from another one following closely behind and mimicking its movements. In flight simulators, the plane always seems to be level when in chase view and the world turns around it. For example, if the player banks her plane, the horizon tilts while the player’s plane appears to be level in the middle of the screen. In driving simulators, the point of view when in chase mode/view is usually somewhat elevated so the player’s car does not obscure the view of the road in front. This view is particularly important for games that involve stunts, such as motocross.

• Rear, side, and front views. These are exterior views of the player’s vehicle from all four sides. If the player’s plane banks, the view does not bank; the ground remains below.

• Free-roaming camera. Generally used only in an instant-replay mode, this enables the camera to be moved anywhere in the world and tilted or rotated to look in any direction. This view is useful for players trying to analyze exactly what happened in a particular encounter.

Views Unique to Military Flight Simulators

The following views are found only in flight simulators—and military ones, at that:

• Ground target view. This is a view of the target on the ground that is currently selected for attack. The camera is positioned at a nearby ground location, facing the target, and does not move. This view lets the player watch incoming missiles or bombs arrive to see whether they accurately hit the target.

• Bomb or missile view. This is the point of view from a recently released bomb or missile, as if it had a camera in its nose (as many modern weapons do). This allows a particularly dramatic perspective as the weapon approaches its target. This view disappears after the weapon detonates, and the perspective returns to the default view.

Views Unique to Driving Simulators

The following views occur only in driving simulators. Obviously, the cars are not drivable from these perspectives, but they are great for instant replays.

• Track-side view. Many real racetracks locate cameras at fixed points around the track, and a good many games emulate this. The game’s point of view can be either locked to a specific location or made to track the player’s car as it moves past. It’s also common to have a routine that automatically makes the display switch from one track-side camera to another to follow the leaders as they go around (see Figure 8).

Figure 8 A track-side view from Need for Speed: Most Wanted

• Grandstand view. This is the traditional spectator’s view of the finish line.

• Blimp view. This is a high aerial view looking straight down onto the racetrack or course, letting you see all the cars at once.

User Interface Design

The biggest challenge in designing the UI of a vehicle simulator is in mapping the vehicle’s real controls to those available on the target machine. For serious simulations, analog controls are essential; the binary D-pads of older handheld controllers don’t allow the kind of precision the player needs to steer accurately. At one time, console machines simply couldn’t support serious simulations, but now that most console machines offer analog joysticks, mapping the controls of a race car to those of a home console machine presents less of a problem.

Vehicle simulations benefit from motion-sensing controllers almost as much as sports games do. Use their tilt sensors to serve as a steering wheel, and their buttons for acceleration and braking. Don’t require the player to turn them by more than about 90 degrees in either direction from the central, neutral position, though. As drivers we can turn a real steering wheel hand-over-hand because it’s circular and fixed in place by the steering column, but the iPhone and Wii controllers are rectangular and not attached to anything. It would be awkward for the player to reposition his hands on them during play.

Simplifications

Military flight simulators always require some simplification from the real thing; you will have to decide how much. Real military pilots require months or years of training, much of it spent sitting in classrooms. Because you want your players to be able to fly the planes within a few minutes of installing the software, you have to make considerable compromises in the realism of the games. You will almost certainly want to reduce the number of instruments in the cockpit and the number of functions that some of them perform.

Flight simulators commonly simplify navigation as well. Modern planes have global positioning systems, but World War I and II pilots still needed celestial navigation skills; they plotted their courses by the stars at night and by landmarks or dead reckoning during the daytime. Because this isn’t the most exciting thing about flying, it’s acceptable to just give the player a map.

Coordinated Flight

Another common simplification that almost all flight simulators make is to produce automatically coordinated flight. Ordinarily, the pilot of an airplane must coordinate the movements of the ailerons and rudder when he turns to prevent the plane from skidding sideways in the air, in the same way that a car skids sideways on wet pavement if it takes a turn too fast. Because the plane has no tires gripping pavement to control the direction it is facing, this can happen even more easily in the air. However, most players have only one control mechanism: the joystick. To simplify flight, the left-right motion of the joystick controls both the rudder and the ailerons simultaneously, producing automatically coordinated flight.

Creating the Sense of Speed

In a flight simulation, simply going fast is rarely the point. Most players either try 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:

• Give the player a speedometer. This is the most obvious way to inform a player of his speed, but it creates a purely logical awareness, not a visceral one. It might also help to give him a tachometer so he can see that the engine is near its maximum potential.

• Vary the driving surface. Don’t present a smooth ribbon of black, but make the road a series of continuously changing dark grays. The rate at which these color gradations move toward the car helps create the feeling of speed. Don’t just use a set of random dots, though, or at high speed the player will just see a static, flickering surface. It’s better to implement these cues as a series of narrow strips parallel to the road’s edges. Also, on roads (as opposed to racetracks), be sure to implement the dotted white line down the center. The sight of the lines flicking by provides a continuous visual cue to the speed, as well as a good way to tell when the vehicle is speeding up or slowing down. (In a flight simulator, the equivalent is to be sure the ground is as detailed as possible.)

• Include roadside objects. A continuous fence, guardrail, or strip of grass doesn’t do much to give the player a feeling of motion. Make sure there are lots of trees, road signs, and bridges. Anything that rises vertically beside the road or that passes over or under the car helps create the impression of motion.

• Use visual effects, such as motion blur. In principle a computer need never display motion blur if its frame rate is high enough, but through watching film and TV, viewers have come to associate motion blur with speed. This technique must be provided by the graphics engine; getting it right is a programming task.

• Use sounds. The sound of the engine is the most obvious auditory cue, but you can also include road noise (the sound the tires make on the pavement), wind noise, and tires squealing as the vehicle rounds corners. Another excellent cue is a Doppler shift as the car passes, or is passed by, some noise-making object.

G-Forces

The driver of any vehicle feels a variety of forces affecting her body: acceleration, deceleration, and centrifugal force. The forces give a lot of valuable feedback about the behavior of the vehicle. Unfortunately, in a home-based simulator, you can’t provide any of those physical feelings, so you have to substitute other indicators. With driving simulators, it isn’t as important because automobiles seldom generate significant g-forces, and the player receives plenty of other visual cues, as the previous section describes.

Military aircraft can generate powerful g-forces, and the engines of modern fighter planes are powerful enough to tear the plane apart if it is mishandled. If you’re doing a realistic simulation, you might want to include this deadly little detail. If so, or if you just want to give the pilot an indication of the g-forces involved, you should include a g-force meter showing the amount of stress being applied to the plane (and pilot). 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, because 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.