Home > Articles > Programming > Games

XNA Game Studio 4.0 Programming: The Game Object and the Default Game Loop

In this chapter, you learn about the features in XNA Game Studio 4.0 , including the game class, the standard game loop and game components.
This chapter is from the book

When you create a new project, many things happen behind the scenes, and many features to help drive the game available to you. In this chapter, you learn about these features, including:

  • The game class
  • The standard game loop
  • Game components

Up until now, you've created new projects and added some code to do other fancy things, but you haven't taken a step back to look at the default game template. Now is a good time to take a look at what is provided for you automatically and the other features available.

What Is in a New Project?

Open Visual Studio and create a new Game Studio 4.0 Windows Game project. Notice that your main project includes two code files (program.cs and game1.cs), and you have a content project you previously used. You can safely ignore everything in program.cs because it is simply the stub that launches the game. As a matter of fact, this isn't even used on Windows Phone 7.

The interesting things that are discussed in this chapter are in game1.cs. Notice first that the Game1 class that is created comes from the Game object provided by Game Studio. The initial starting project gives you everything you need to start creating a game. It has a spot for initialization, a spot to load the content your game needs, a spot to update the game state, and a spot to render everything.

More things happen behind the scenes than you are probably aware of, however. Start with the first thing you see in the constructor, creating the GraphicsDeviceManager.

graphics = new GraphicsDeviceManager(this);

This one line of code starts a chain reaction of operations. It naturally creates a new GraphicsDeviceManager (which is discussed in just a moment), but it does more than that. This object implements IGraphicsDeviceService and IGraphicsDeviceManager. When you create the object, it takes the game parameter you've passed in (that is, the this parameter) and adds itself to the Services property of the game object.

After the graphics device manager has been added to the services list, the actual graphics device is created when the constructor has finished executing. The default options work just fine, but you actually do have some control over the settings the device has.

Notice that quite a few different properties on this object can be used to control how the device is created or to get information about it. The first one is the GraphicsDevice. Right now, it hasn't been created yet, but after it has been, it can be accessed here. You most likely never need it, though, because the GraphicsDevice is a property of the Game itself.

The GraphicsProfile is another property you can access. Profiles are discussed in Chapter 4, "Introduction to 3D Graphics". Next is the IsFullScreen property that behaves differently depending on the platform you run. The default value here is false, although on Xbox 360, it doesn't matter what this is set as because you are always full screen on that platform. On Windows, setting this to true causes the device to be created in what is called full screen exclusive mode, and your rendering encompasses the entire screen. On Windows Phone 7, this controls whether the system tray bar is visible or not visible.

The next set of properties is the most commonly changed, and it includes the preferences. Because they are preferences and not requirements, the runtime attempts to use these settings, and if it cannot use them, it falls back to what it feels is the closest to what you requested. These properties are PreferMultisampling, PreferredBackBufferWidth, PreferBackBufferHeight, PreferBackBufferFormat, and PreferDepthStencilFormat.

The back buffer is where your content is rendered, and the sizes in these preferences (width and height), control how large that area is. On Windows, in nonfull screen mode, this also controls the size of the window. In full screen mode, it controls the resolution of the monitor when it takes exclusive control of it. On Xbox 360 and Windows Phone 7, the devices have a built-in native resolution. For Windows Phone 7, the device has a resolution of 480x800 (in portrait mode), whereas the Xbox is configurable. On each of these platforms, if you ask for a different back buffer resolution, it is scaled to the native device resolution.

Multisampling is the process used to remove what are called the "jaggies" from rendered images. These jagged edges are formed normally on the edges of objects or on lines that are not on pixel boundaries (for example, nonhorizontal or vertical lines). Multisampling blends each pixel with other pixels around it to help soften these jagged edges. It does this by rendering the image larger and blending multiple pixels down to a single pixel. Although it doesn't necessarily remove the jagged edges, it certainly can help. There is a performance cost for doing this, so this defaults to false.

The last two preferences are the formats for the back buffer and the depth stencil. Formats are used to describe how data is laid out for the final rendered image. For the back buffer, this is how the color is laid out, and the default for this is actually SurfaceFormat.Color. This is a 32-bit format that has 8 bits for red, green, blue, and alpha. The depth stencil buffer formats control how many bits are used for the depth buffer and stencil buffer.

The last two properties are SupportedOrientations, which is mainly used for Windows Phone 7, and SynchronizeWithVerticalRetrace. Synchronizing with the vertical retrace is a way to prevent tearing by pausing until the device is ready to render the entire screen at once. These are discussed in depth in Chapter 11, "Understanding Performance" when performance and measurement are discussed.

There are also six different events you can hook off of the graphics object, most of which are self-explanatory based on the names. The one interesting one is PreparingDeviceSettings. This event is triggered right before the device is created, and it gives you the opportunity to override any of the settings before the device is actually created. Use this only if you know the device supports the settings you request.

There are also two methods on the object, ApplyChanges which attempts to instantly update the device to the current settings (or create a new device if required), and ToggleFullscreen, which makes a windowed game full screen and a full screen game windowed during runtime. Using either of these is rarely required.

The last thing the constructor does is set the root directory of the automatically created content manager to "Content," which is where your content project places the content you add to your game. The content manager is created for you when the game is created, so you can begin using it immediately. The content manager is discussed more in depth in Chapter 9, "Using the Content Pipeline."

Content.RootDirectory = "Content";

The default template has overrides for five common methods: Initialize, LoadContent, UnloadContent, Update, and Draw. Although nothing happens in Initialize and UnloadContent, the other three have basic stub code. The LoadContent method creates the sprite batch object you almost certainly need. The Draw method clears the screen to the infamous CornflowerBlue color. Finally, the Update method adds a quick check to see if you're pressing the Back button on your controller to see if it should exit the game. We get into the flow of these methods and how they're used in just a moment, but first, let's take a look at the Game class itself.

InformIT Promotional Mailings & Special Offers

I would like to receive exclusive offers and hear about products from InformIT and its family of brands. I can unsubscribe at any time.


Pearson Education, Inc., 221 River Street, Hoboken, New Jersey 07030, (Pearson) presents this site to provide information about products and services that can be purchased through this site.

This privacy notice provides an overview of our commitment to privacy and describes how we collect, protect, use and share personal information collected through this site. Please note that other Pearson websites and online products and services have their own separate privacy policies.

Collection and Use of Information

To conduct business and deliver products and services, Pearson collects and uses personal information in several ways in connection with this site, including:

Questions and Inquiries

For inquiries and questions, we collect the inquiry or question, together with name, contact details (email address, phone number and mailing address) and any other additional information voluntarily submitted to us through a Contact Us form or an email. We use this information to address the inquiry and respond to the question.

Online Store

For orders and purchases placed through our online store on this site, we collect order details, name, institution name and address (if applicable), email address, phone number, shipping and billing addresses, credit/debit card information, shipping options and any instructions. We use this information to complete transactions, fulfill orders, communicate with individuals placing orders or visiting the online store, and for related purposes.


Pearson may offer opportunities to provide feedback or participate in surveys, including surveys evaluating Pearson products, services or sites. Participation is voluntary. Pearson collects information requested in the survey questions and uses the information to evaluate, support, maintain and improve products, services or sites, develop new products and services, conduct educational research and for other purposes specified in the survey.

Contests and Drawings

Occasionally, we may sponsor a contest or drawing. Participation is optional. Pearson collects name, contact information and other information specified on the entry form for the contest or drawing to conduct the contest or drawing. Pearson may collect additional personal information from the winners of a contest or drawing in order to award the prize and for tax reporting purposes, as required by law.


If you have elected to receive email newsletters or promotional mailings and special offers but want to unsubscribe, simply email information@informit.com.

Service Announcements

On rare occasions it is necessary to send out a strictly service related announcement. For instance, if our service is temporarily suspended for maintenance we might send users an email. Generally, users may not opt-out of these communications, though they can deactivate their account information. However, these communications are not promotional in nature.

Customer Service

We communicate with users on a regular basis to provide requested services and in regard to issues relating to their account we reply via email or phone in accordance with the users' wishes when a user submits their information through our Contact Us form.

Other Collection and Use of Information

Application and System Logs

Pearson automatically collects log data to help ensure the delivery, availability and security of this site. Log data may include technical information about how a user or visitor connected to this site, such as browser type, type of computer/device, operating system, internet service provider and IP address. We use this information for support purposes and to monitor the health of the site, identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents and appropriately scale computing resources.

Web Analytics

Pearson may use third party web trend analytical services, including Google Analytics, to collect visitor information, such as IP addresses, browser types, referring pages, pages visited and time spent on a particular site. While these analytical services collect and report information on an anonymous basis, they may use cookies to gather web trend information. The information gathered may enable Pearson (but not the third party web trend services) to link information with application and system log data. Pearson uses this information for system administration and to identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents, appropriately scale computing resources and otherwise support and deliver this site and its services.

Cookies and Related Technologies

This site uses cookies and similar technologies to personalize content, measure traffic patterns, control security, track use and access of information on this site, and provide interest-based messages and advertising. Users can manage and block the use of cookies through their browser. Disabling or blocking certain cookies may limit the functionality of this site.

Do Not Track

This site currently does not respond to Do Not Track signals.


Pearson uses appropriate physical, administrative and technical security measures to protect personal information from unauthorized access, use and disclosure.


This site is not directed to children under the age of 13.


Pearson may send or direct marketing communications to users, provided that

  • Pearson will not use personal information collected or processed as a K-12 school service provider for the purpose of directed or targeted advertising.
  • Such marketing is consistent with applicable law and Pearson's legal obligations.
  • Pearson will not knowingly direct or send marketing communications to an individual who has expressed a preference not to receive marketing.
  • Where required by applicable law, express or implied consent to marketing exists and has not been withdrawn.

Pearson may provide personal information to a third party service provider on a restricted basis to provide marketing solely on behalf of Pearson or an affiliate or customer for whom Pearson is a service provider. Marketing preferences may be changed at any time.

Correcting/Updating Personal Information

If a user's personally identifiable information changes (such as your postal address or email address), we provide a way to correct or update that user's personal data provided to us. This can be done on the Account page. If a user no longer desires our service and desires to delete his or her account, please contact us at customer-service@informit.com and we will process the deletion of a user's account.


Users can always make an informed choice as to whether they should proceed with certain services offered by InformIT. If you choose to remove yourself from our mailing list(s) simply visit the following page and uncheck any communication you no longer want to receive: www.informit.com/u.aspx.

Sale of Personal Information

Pearson does not rent or sell personal information in exchange for any payment of money.

While Pearson does not sell personal information, as defined in Nevada law, Nevada residents may email a request for no sale of their personal information to NevadaDesignatedRequest@pearson.com.

Supplemental Privacy Statement for California Residents

California residents should read our Supplemental privacy statement for California residents in conjunction with this Privacy Notice. The Supplemental privacy statement for California residents explains Pearson's commitment to comply with California law and applies to personal information of California residents collected in connection with this site and the Services.

Sharing and Disclosure

Pearson may disclose personal information, as follows:

  • As required by law.
  • With the consent of the individual (or their parent, if the individual is a minor)
  • In response to a subpoena, court order or legal process, to the extent permitted or required by law
  • To protect the security and safety of individuals, data, assets and systems, consistent with applicable law
  • In connection the sale, joint venture or other transfer of some or all of its company or assets, subject to the provisions of this Privacy Notice
  • To investigate or address actual or suspected fraud or other illegal activities
  • To exercise its legal rights, including enforcement of the Terms of Use for this site or another contract
  • To affiliated Pearson companies and other companies and organizations who perform work for Pearson and are obligated to protect the privacy of personal information consistent with this Privacy Notice
  • To a school, organization, company or government agency, where Pearson collects or processes the personal information in a school setting or on behalf of such organization, company or government agency.


This web site contains links to other sites. Please be aware that we are not responsible for the privacy practices of such other sites. We encourage our users to be aware when they leave our site and to read the privacy statements of each and every web site that collects Personal Information. This privacy statement applies solely to information collected by this web site.

Requests and Contact

Please contact us about this Privacy Notice or if you have any requests or questions relating to the privacy of your personal information.

Changes to this Privacy Notice

We may revise this Privacy Notice through an updated posting. We will identify the effective date of the revision in the posting. Often, updates are made to provide greater clarity or to comply with changes in regulatory requirements. If the updates involve material changes to the collection, protection, use or disclosure of Personal Information, Pearson will provide notice of the change through a conspicuous notice on this site or other appropriate way. Continued use of the site after the effective date of a posted revision evidences acceptance. Please contact us if you have questions or concerns about the Privacy Notice or any objection to any revisions.

Last Update: November 17, 2020