DirectX Game Programming Introduction

What is DirectX?

DirectX is a software development kit (SDK) for the Windows operating system that allows programmers to directly access a computer's hardware without going through the win32 GDI, which is slow. This translates into faster games. Microsoft created this SDK to allow game developers to use Windows instead of DOS as a platform. Previously, all games were developed for DOS because the win32 GDI was too slow. Microsoft didn't want to risk losing gamers to alternate operating systems, so they introduced a SDK to encourage developers to target the windows platform. Microsoft's first attempt was a failure. However, after a few revisions, Microsoft had got it right and had pleased game developers. Currently all major retail computer games are targeted for the Windows platform.

How does it benefit a Game Programmer?

Let's face it. DOS is dead. People are not willing to go though the hassle to get a DOS game working anymore (remember extended memory and load high commands?). If you want to do professional programming nowadays, you only have one option: DirectX. Sure, Linux and Macintosh are other possibilities, but currently they don't have anywhere near the user base that Windows has.

The switch from DOS to DirectX is a BIG change. You need to change the way you design and write code. In addition, games need to be made event driven as opposed to a procedural C program. At first, DirectX seems difficult to most people. Even the experts complain about it now and then. But after a little practice and learning the ropes, it isn't too bad and the advantages far outweigh the investment in learning it.

Let's look at the positive and negative aspects of DirectX:

Positive

1. No Drivers to Develop

Programmers don't have to write drivers for each different type of hardware there is! Windows does this for us. DirectX just provides us with a standard way to access the hardware and Windows takes care of the rest. We just write our game using DirectX (which is machine independent) and theoretically that same game should be able to run on all Windows 95, Windows 98, and Windows NT computers in existence. Windows NT DirectX support is still under development, though.

2. Larger User Base

Microsoft Windows 95/98/NT in running on approximately 90% of desktop computers. This means that you will have a huge user base of potential customers that are able to run your game. Porting a game to additional operating systems is a possibility, especially with the emerging Linux market. Cross platform games gain a deeper respect from end users than a game that is "Windows only."

3. Easier for End User

Microsoft has standardized game setup and the graphical user interface to some extent. This makes it easier for end users to setup and run your games. This hopefully will cut down on technical support calls from people who don't know what they are doing (and you'll have to tell them to rtfm); if they've installed one windows products, they know how to do them all.

Negative

1. Changes Game Program Structure

Writing a game for Windows is a lot different from a DOS game. You need to get used to Windows messages and how Windows programming works. You also need to change how you structure a game. In DOS, everything was structured and you knew exactly what was going to happen and when it was going to happen. Now with Windows, you get "windows messages" that tell you what is happening. You need to structure your program to respond to these messages that Windows sends you. Simply put, your game is now a slave!

2. Supports a Monopoly

DirectX is developed by Microsoft and Bill Gates. This can be a negative or positive, depending on how you look at it. Some people are all wacko and naive and refuse to buy a product from Microsoft because they are a monopoly. People like that need to open up and understand that Microsoft does make some good products. In my opinion, DirectX is one of those good products. However, I put this in the negative category because Microsoft is a monopoly. Being a monopoly, Microsoft forces all us developers to develop for whatever they throw at us. A lot of other companies out there could be a lot more innovative if Microsoft did not have control of the entire software side of game development. Well, that's just my two cents.

Analysis

Programming games using the DirectX API directly can be tedious and a source of bugs to many new programmers. In today's fast paced gaming environment, most people would rather spend their limited time developing their ideas as opposed to reinventing the wheel. For this, we recommend using the Allegro Game Programming Library. This library provides a cleaner and easier way to access the same functions as coding directly to the DirectX API. Development time is greatly shortened, thereby allowing more time to write a creative, innovative game with better game play. For more information, visit our Allegro page.

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