CHAPTER 5

1. CHAPTER 5 Input Control © 2008 Cengage Learning EMEA

2. LEARNING OBJECTIVES • In this chapter you will learn about: • Input devices • Six classes of input • DirectInput • DirectInput device setup (keyboard, mouse or joystick) • Creating a DirectInput object • Creating a DirectInput device • Setting the data format of a DirectInput device • Setting the cooperative level of a DirectInput device • Acquiring a DirectInput device • Reading data from a DirectInput device • Buffered and immediate data (keyboard, mouse or joystick) • Action mapping • The specification of actions • Setting up an action map • Applying an action map to physical devices • Applying an action map to a device • Retrieving action map data • Force feedback • Setting up a force feedback device • Using effects • XInput

3. INPUT DEVICES • We classify physical input devices into two primary categories: • keyboard devices • pointing devices. • The mouse is by far the most popular and commonly used pointing device. • It generates two independent values converted by some API, device interface, or user program into positional data that can be interpreted as screen coordinates. • This direct approach is, however, rarely used and these two independent values generated by the device are more commonly interpreted by the device driver as velocities.

4. INPUT DEVICES • The main purpose behind using velocities, rather than distance values, lies with the desire to create a variable-sensitivity input device. • Variable sensitivity refers to slow movements from rest resulting in nominal changes with rapid mouse movements leading to large changes in the cursor’s onscreen position.

5. INPUT DEVICES • The mouse is referred to as a relative-positioning device. • Absolute positioning provides a way of linking onscreen data with the device’s physical position. • The joystick is another very important input device, especially to the world of computer gaming and simulations. • In its simplest form we interpret the motion of its stick in both an x and a y direction. These values are then, just as with the mouse, translated into velocities and subsequently integrated into screen coordinates.

6. INPUT DEVICES

7. INPUT DEVICES

8. SIX CLASSES OF INPUT • We can identify six classes of logical input devices: • choice devices • locator devices • pick devices • string devices • stroke devices • valuators.

9. DIRECTINPUT • DirectInput is DirectX’s primary input processing API. • It provides hardware-independent input control for keyboards, mice, joysticks, gamepads, steering wheels, flight yokes, space balls, paddles, etc. • DirectInput’s hardware-independent nature can be attributed to the API interfacing directly with the device drivers.

10. DIRECTINPUT • DirectInput is thus responsible for the processing of messages sent to and received from physical input devices.

11. DirectInput Device Setup (Keyboard, Mouse, or Joystick) • Creating a DirectInput Object • Creating a DirectInput Device • Setting the Data Format of a DirectInput Device • Setting the Cooperative Level of a DirectInput Device • Acquiring the DirectInput Device • Reading Data from a DirectInput Device [see the textbook and the DirectInput code samples on the book’s website for a complete discussion].

12. Device Data • Buffered as an alternative to Immediate Keyboard Data • Buffered as an Alternative to Immediate Mouse Data • Buffered as an Alternative to Immediate Joystick Data [see the textbook and the DirectInput code samples on the book’s website for a complete discussion].

13. Action Mapping • Action mapping eliminates the need for hard coded event-object mapping by binding events to virtual control objects • Specifying the Actions • Setting up the Action Map • Applying an Action Map to Physical Devices • Applying the Action Map to a Device • Retrieving Action Map Data

14. Force Feedback • Force feedback is an all-encompassing term used to describe input devices equipped with actuators, motors and resistance-inducing elements that are used for exerting vibration-based forces.

15. Force Feedback • Setting up a Force Feedback Device • Using Effects [see the textbook and the DirectInput Force Feedback code sample on the book’s website for a complete discussion].

16. XINPUT • XInput, introduced with the release of the Xbox 360 gaming console, allows any computer running Windows XP SP1 or later to interface with an Xbox 360 controller. [see the textbook and the XInput code sample on the book’s website for a complete discussion].