1. Microsoft Tech Days 2012 Cheezia: Developing a Windows Phone XNA Game Rodrigo Barretto Software Engineer - MCPD on Windows Phone rodrigo.barretto@attido.com http://www.attido.com

2. Agenda Cheezia XNA Overview Game State Management Input Handling Update Method Draw Method Sound Effects Configuration Files as Resources Tombstoning Configuring Metadata Files References 2

3. Cheezia Puzzle / Reaction game Originally developed in Flash for iOS and Android devices using Adobe AIR Windows Phone version: Over 54k downloads Featured in Channel 9’s Hot Apps Full source code is available at http://www.attido.com/techdays 3

4. XNA Overview High performance game framework Enables creation of 2D and 3D games for Windows Phones, Xbox 360 and PC Provides a content pipeline that compiles game assets into XNBs Polling loop model instead of event driven Provides GraphicsDeviceManager and ContentManager 4 Initialize Load Content UpdateDraw Unload Content

5. Game State Management ScreenManager Inherits from DrawableGameComponent Manages one or more GameScreen instances Calls Update and Draw of each GameScreen instance Routes input to the topmost active screen Activates / deactivates each GameScreen instance GameScreen 5 Activate Deactivate Unload HandleInput Update Draw

6. Game State Management InputState Reads input from keyboard, gamepad and touchpanel InputAction Evaluates which buttons and keys have been pressed IScreenFactory Instance is added to Game.Services CreateScreen -> Activator.CreateInstance(screenType) 6

7. Input Handling ScreenManager refreshes input states in each Update XNA supports up to 4 input points Special button: Back Accelerometer is event driven Bind to ReadingChanged event and call Start Guide.IsScreenSaverEnabled Guide exposes virtual keyboard: BeginShowKeyboardInput / EndShowKeyboardInput 7 HandleInputInputStateGesturesTouchStateHandleInputInputAction.Evaluate

8. Update Method Update game variables Speed, acceleration, position, score, timer, animations,... Check for game over / level accomplished / achievement unlocked,... GameTime exposes important properties ElapsedGameTime TotalGameTime IsRunningSlowly 8

9. Draw Method Draws into the back buffer Rendered in the next frame Order matters!! Transparency from.png or Color Key property (default is Magenta) XNA supports.png,.bmp,.jpg,.tga,.dds,.spritefont,.x,.fx,.fbx Use fonts from: The system: default is Segoe UI Mono Own.ttf installed on development machine.bmp file 9 GraphicsDevice.ClearSpriteBatch.BeginSpriteBatch.End SpriteBatch.Draw SpriteBatch.DrawString

10. Sound Effects Loaded as content items SoundEffect Plays the sound until the end SoundEffectInstance provides more control: Volume, pitch, pan Playback capabilities XNA supports.wav,.mp3,.wma XACT sound fields are not supported on the phone 10 Content Manager Sound Effect Play Pause Resume Stop Sound Effect Instance Volume Pitch Pan

11. Configuration Files as Resources Additional.xml files to configure: Level design Achievement related data... Corresponding classes must be implemented in a separate Game Library project Automatically parsed when loading via Content Manager 11

12. Tombstoning The player might be interrupted while playing Needs to maintain the illusion that the game was never interrupted Bind to PhoneApplicationService’s events in main game class Launching, Activated, Deactivated, Closing ScreenManager takes care of activating/deactivating each screen and knows if instances were preserved (fast app switching) Save and load states and values of properties of each screen Temporary data -> PhoneApplicationService’s state dictionary Persistent data -> Isolated Storage 12 Call SMS Start Button Search Button Camera Button Screen Lock

13. Configuring Metadata Files Make sure you fill them with information regarding your game Title Description Author Publisher Version Genre: ”Apps.Games” 13

14. References App Hub http://create.msdn.com/ http://create.msdn.com/en-US/education/ MSDN Library – XNA Game Studio 4.0 http://msdn.microsoft.com/en-us/library/bb200104.aspx 15

15. Microsoft Tech Days 2012 Cheezia: Developing a Windows Phone XNA Game Rodrigo Barretto Software Engineer - MCPD on Windows Phone rodrigo.barretto@attido.com http://www.attido.com