The definitive guide to Microsoft's advanced, high-performance mulit-media componants.
What to Expect
The first version of DirectX was actually called the Game SDK. We created it because we saw an enormous untapped potential in Microsoft Windows-the potential to host fast-action games. Most of us on the project had some notion, in a dim, distracted sort of way, that the scope of our efforts could be bigger than we realized. Certainly there must be uses for our work beyond computer games, but we were too busy sweating out code to give much thought to the matter. Only when the Office group here at Microsoft contacted us and requested information about "that Game SDK thing" did we begin to have visions of grandeur. We had never considered that smooth animation could be applied to pie charts as well as to spaceships. Consequently, the Game SDK had a life span Of only one version-our work burst out of its gaming cocoon into a larger world of multimedia. DirectDraw, DirectPlay, and all the other "DirectSomethings" became known as DirectX.
just as DirectX is now recognized as being useful across a wide spectrum of applications, we wanted this book to be broadly applicable as well. We especially wanted to avoid authoring another book that describes how to create a particular type of game. You won't find chapters about creating your own 3D engine, your own side-scrolling engine, or your own sprite system inside this book. The bookstore shelves are already packed with these types of books, and most of theconcepts discussed in them can be implemented using DirectX. Once you've read this book, you'll have all the knowledge you need to make DirectX dance to your bidding, whether you're creating the next chart-topping game or a tool for analyzing the stock market.
Windows Stuff
Since many PC games are MS-DOS-based, it follows that many PC game developers will be new to Windows programming. It's beyond the scope of our efforts here to teach programming for Windows-we just don't have the space. We do promise to keep the Windows programming overhead to an absolute minimum, though. If you find yourself having difficulty with some of the fundamentals of Windows programming, there are books in the computer section of any bookstore that can help you out. In particular, Charles Petzold's programming Windows is considered by most to be the definitive introductory text in this area.
Languages
While DirectX can probably be accessed most easily using C or C++, it's not language specific. For example, Microsoft offers the Microsoft SDK for Java, a class library that makes DirectX services available to java applications. Thirdparty vendors offer controls using Microsoft's ActiveX standard, which can be used to access DirectX functionality from Web pages or from languages that don't support it directly. But while DirectX isn't language specific, most of its developers do have a preferred language. Being operating system people, most of us prefer to code in C. As you browse through the SDK sample programs, you'll find some source code written in C++; but for the most part, you should be prepared to read a lot of C.
We selected C for most of the SDK sample programs primarily because it's what we're most familiar with-DirectX itself is predominantly written in C, and we use C every day. While C++ might be a great candidate for building your application, we thought object-oriented constructs would tend to obscure the behaviors we wanted to illustrate. And of course, if you can read C++, you can read C, but the reverse is not necessarily true.
Code Examples
As we mentioned earlier in this chapter, our goal is not to teach game programming as much as it is to teach DirectX. Certainly, because DirectX was originally designed for computer games, it's often easiest to illustrate a concept with an example that has a gamelike feel, but we'll try to keep things from getting too involved. We've whittled the code samples down to the absolute minimum required to demonstrate a concept, eliminating unnecessary window dressing such as toolkits, user interface code, and complex game logic. So don' t expect anything too flashy, just raw DirectX.
COM provides a foundation for component-based software development. It's easy to use and offers many benefits. COM's reputation has suffered unfairly because of its roots in OLE-the mere mention of which often causes developers to twitch nervously. OLE is a flexible, powerful system with a well-deserved reputation for being complex, difficult to work with, and potentially slow. COM, on the other hand, is simple, elegant, and adds very little overhead to an ap plication. The two technologies now lead independent, productive lives.
If you're interested in learning more about COM, perhaps even using it to create your own software components, you'll find several books listed in the appendix. Fortunately, to develop applications with DirectX, you only need to know how to use some of the basic COM functionality; you won' t have to implement it. For our purposes here, we'll attempt what might well be the world's most compact (and hopefully, effective) introduction.
COM is a standard that defines how software objects or components interact with one another. A COM object provides access to its functionality via one or more programming interfaces. An interface is a functional group of object methods that never changes. COM has become the foundation of a number of Microsoft products, including OLE and DirectX. DirectX's current implementation of COM is literally as simple as it can get and still be called COMsome purists would even disagree with this, depending on the finer points of their favorite definition. To be considered COM-compliant, an object must inherit its interfaces from the ancestor of all COM interfaces, IUnknown. This means that, at minimum, the interface must implement the lUnknown methods, shown in Table 2-1 on the following page. These three methods control an object's life span and provide access to the object through its interfaces.
Lifetime Management
The idea that an object can support multiple users or clients is fundamental to COM. Because no single client has knowledge of all the other clients, it's not possible for any client to know when an object should be destroyed-another client could still be using the object. This means that the object itself must be...
Acknowledgments xxv Introduction xxvii PartI: DIRECTX 3 Chapter 1 Introducing DirectX 3 Chapter 2 Groundwork 11 Chapter 3 Getting Started with DirectX 21
Part II: DIRECTDRAW 33 Chapter 4 Introducing DirectDraw 33 Chapter 5 Using DirectDraw 43 Chapter 6 Surfaces 63 Chapter 7 Rendering 83 Chapter 8 Blitting 95 Chapter 9 Page Flipping 113 Chapter 10 Palettes 133 Chapter 11 Overlays 147 Chapter 12 Windowed DirectDraw 165 Chapter 13 Applying DirectDraw 187
Part III: DIRECTSOUND 203 Chapter 14 Introducing DirectSound 203 Chapter 15 DirectSound Playback 223 Chapter 16 DirectSound in Three Dimensions 249 Chapter 17 Sound Capture and Notification 267
Part IV: DIRECTPLAY 283 Chapter 18 Introducing DirectPlay 283 Chapter 19 Using DirectPlay 293 Chapter 20 Message Handling 317 Chapter 21 Lobbies 361 Chapter 22 Applying DirectPlay 381
Part V: DIRECTINPUT 397 Chapter 23 Introducing DirectInput 397 Chapter 24 Mouse Input 427 Chapter 25 Joystick Input 439 Chapter 26 Keyboard Input 451 Chapter 27 Force Feedback 459
Part VI: DIRECTSETUP 493 Chapter 28 Using DirectSetup 493 Chapter 29 Wrapping It Up 513 Appendix 525 Index 527
Overview
The definitive guide to Microsoft's advanced, high-performance mulit-media componants.