Hardly any C# code is needed to generate and display a basic XNA game win- dow—like the one shown in Figure 2-3. Chapter 2 explained how to create a game studio project for a Windows PC, a Zune device, or the Xbox 360 platform. These projects can be created using the Xbox 360, Zune, or Windows Game project tem-
F I G U R E 3 - 1
XNA application flow
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plates—they generate practically identical code. For example, the only difference be- tween the Windows and Xbox 360 templates is the namespace for the game class.
The Windows template assigns the name WindowsGame1 by default and the Xbox 360 assigns the namespace Xbox360Game1—that’s it. These templates provide the basic foundation you need to create an XNA game window.
Although the XNA code in these templates is basically the same, the XNA frame- work references for Windows, Zune, and Xbox 360 projects are different. If you want, you can write all of your code in one environment and then reference it in an Xbox 360, Zune, or Windows project to run it. Microsoft has intentionally made window creation and portability between projects simple. Obviously, Microsoft wants you to take the platform beyond the outer limits.
Initializing the Game Application
When you want to create a new XNA game project, the easiest method is to use the project templates that come with GS because the template adds the necessary project references for you. After you have installed the XNA framework, you can begin a new project, by following these steps:
1. From the Start menu, select Programs and choose Microsoft XNA Game Studio. Depending on your environment, you could also choose to open Microsoft Visual Studio, Microsoft Visual C#, or Microsoft Visual C#
Express Edition.
2. From the main Visual Studio or Visual C# window, choose File | New Project.
3. Choose either the Windows Game, Zune, or Xbox 360 Game template.
Like any other C# application, an XNA application begins by referencing the as- semblies and the namespaces required by the program. To plug into the XNA plat- form, you will need references to the XNA framework along with namespaces for Audio, Content, GamerServices, Graphics, Input, .Media, .Net and .Storage compo- nents. When you use a game project template, these namespaces are automatically added for you in the default Game1.cs file that is generated. To avoid potential nam- ing conflicts for this class (with any identically named classes), a namespace is needed for the game class. For example, the Xbox 360 Game project template generates the namespaceXbox360Game1 and the Windows Game project template generates the namespaceWindowsGame1. The namespace is followed by a class declaration for the game application class, which both project templates declare asGame1. The templates also add the required assembly references for you.
C H A P T E R 3
BehindtheGameWindow
GraphicsDeviceManager
Every XNA application requires aGraphicsDeviceManagerobject to handle the configuration and management of the graphics device. TheGraphicsDeviceclass is used for drawing. TheGraphicsDeviceManagerobject is declared at the mod- ule level:
GraphicsDeviceManager graphics;
TheGraphicsDeviceManagerobject is initialized in the game class construc- tor,Game1():
graphics = new GraphicsDeviceManager(this);
SpriteBatch
TheSpriteBatchobject provides access to methods for drawing images, referred to assprites, in the game window. Only oneSpriteBatchobject is needed in your game, and you can use it to draw as many sprites as you choose. Microsoft’s game project template declares a SpriteBatchobject at the top of the game class for you:
SpriteBatch spriteBatch;
TheSpriteBatchobject is then initialized in theLoadContent()method:
spriteBatch = new SpriteBatch(GraphicsDevice);
ContentManager
TheContentManageris used to load, manage, and dispose of binary media con- tent through the content pipeline. When it is referenced in the game project, this ob- ject can load graphics and media content. If you generate your game projects with an XNA template, the root directory for your content will be defined in the constructor of the game class,Game1():
Content.RootDirectory = "Content";
With this declaration in place, you will need to reference your image, audio, and models from this Content node in the Solution Explorer.
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Initialize()
After theGraphicsDeviceManagerobject has been created, you can override the Initialize()method to trap the one-time game startup event.
Initialize()is a natural place to trigger basic setup activities such as the fol- lowing:
Setting window properties such as the title or full-screen options
Setting up your camera to view a 3D game world
Initializing vertices for storing position, color, and image coordinates that you will use throughout the program
Initializing shaders to convert your primitive objects to pixel output
Setting up other game objects LoadContent()
TheLoadContent()override method is generated by the game project templates.
The method is used to load binary image and model content through the content pipeline.LoadContent()is called afterInitialize(), and for our examples, this is sufficient to handle our needs. However, if you want to experiment with DeviceReset events on your own, you can useLoadContent()to reload your media resources when theDeviceResetevent occurs.