Game Engine Architecture

348 8. Human Interface Devices (HID)

and size information can be read by the console via a Bluetooth wireless con-

nection.

The position and orientation of the line segment formed by the two dots

can be used to determine the pitch, yaw, and roll of the WiiMote (as long as it

is being pointed toward the sensor bar). By looking at the separation between

the dots, soft ware can also determine how close or far away the WiiMote is

from the TV. Some soft ware also makes use of the sizes of the dots. This is il-

lustrated in Figure 8.8.

Another popular camera device is Sony’s EyeToy for the PlayStation line

of consoles, shown in Figure 8.9. This device is basically a high quality color

camera, which can be used for a wide range of applications. It can be used

for simple video conferencing, like any web cam. It could also conceivably be

used much like the WiiMote’s IR camera, for position, orientation, and depth

sensing. The gamut of possibilities for these kinds of advanced input devices

has only begun to be tapped by the gaming community.

8.4 Types of Outputs

Human interface devices are primarily used to transmit inputs from the play-

er to the game soft ware. However, some HIDs can also provide feedback to

the human player via various kinds of outputs.

8.4.1. Rumble

Game pads like the PlayStation’s DualShock line of controllers and the Xbox

and Xbox 360 controllers have a rumble feature. This allows the controller to

vibrate in the player’s hands, simulating the turbulence or impacts that the

Figure 8.8. The Wii sensor bar houses two infrared LEDs which produce two bright spots on

the image recorded by the WiiMote’s IR camera.

Figure 8.9. Sony’s Eye-
Toy for the PlaySta-
tion3.