Introducing XNA for WP7 Rob Fonseca-Ensor discusses XNA, a game development framework for Windows Phone 7. XNA allows developers to create 2D and 3D games using a game loop model and includes APIs for graphics, input handling, and more. It is relatively portable across Xbox, PC, Zune and now WP7. The Content Pipeline is used to manage game assets. Input can be read from the GamePad, TouchPanel, and gestures. Components can encapsulate responsibilities in games to keep code organized as the game grows more complex.

1. Introducing XNA for WP7Rob Fonseca-Ensor

2. MeI help run the CWDNUGI’m co-authoring a WROX book on WP7I’ve got an iPhone game on the app store

3. I write Silverlight apps ALL DAY LONG (for Infusion)www.robfe.com | rob@robfe.com | @robfe | meetup.com/cwdnug

4. What is it.NET framework for gamesXBOX, PC, ZuneNow WP7Creator’s Clubhttp://creators.xna.comParallel set of .NET APIsEven more cut down on WP7Relatively Portable

5. When to use itSilverlight is event drivenIt reacts to the userSuitable for some gamesXNA is a game loopThe user reacts to the game3D graphicsPerformance

6. Running an XNA game

7. The Content Pipelinehttp://msdn.microsoft.com/en-us/library/bb447745.aspx

8. 2D drawing with the SpriteBatchA class that manages the rendering of 2D sprites (textures) and fontsBeginStarts a batchDrawPaints a Texture2D to the screenDrawStringPaints a SpriteFont + a string to the screenEndCommit the batch

9. As time goes byTrack how quickly by inspecting the GameTimeAllows proportional movementEver tried to play a 286 game on a 66 MHz beast?React to time passing within UpdateUpdate is less likely to skip than DrawYou don’t want to miss a poll of some user input

10. Geometry APIsVector2+ - * / another Vector2 or a float.Normalize, Length, LengthSquaredSystem.MathMath.ATan2(x,y) to calculate anglesCos and Sin to turn an angle into a Vector2MathHelperThe XNA Version of System.MathConstants: PI, TwoPi, PiOverFour, E, Log10EMethods: DegreesToRadians, Clamp, CatMullRom, Lerp

11. Reading User InputGamePadAn XBOX relicCheck if the user is pressing “back” (exit or menu)TouchPanelGetState()Picks up all the currently touched pointsEach touch has an IDReadGesture()Higher level APIFilter with EnabledGestures

12. Encapsulation with GameComponentUpdate or Draw will get bigger as your game gets builtSeparate responsibilities into componentsDon’t treat these as sprites – they should be long-livedShare state via Game.ServicesGameComponent has parallel Initialize, LoadComponent, Update and Draw (DrawableGameComponent)