XNA Development - Digital Transfusion

Creating Games For Windows, Xbox 360, and Windows Phone 7
Ryan Plemons
Where to begin?
All demos in this slide deck are built with XNA 4. To follow
along, you will need the following:
 Windows 7 or Vista
 A DirectX 9.1c capable graphic card (or better) with up to
date drivers and DirectX runtime. If you’d like to debug
Windows Phone 7 XNA projects you need a DirectX 10
capable graphic card (or better).
 Windows Phone 7 Development Tools
 XNA 4 is part of this package, and will install VS2010 Express.
If you use a better version of VS2010, then the templates are
installed for it as well.
 This will install an emulator for WP7 development
What is XNA?
XNA = XNA's Not Acronymed
 XNA is a powerful .Net API that handles graphics,
sounds, inputs, networking, and storage that targets
multiple platforms within the Microsoft envrionment.
 Windows
 Windows Phone 7
 Xbox 360
 Zune
 (and more to come)…
Can I get an upgrade?
If you are a student you can take advangate of the
Dreamspark program. You can get a copy of:
 Windows 7/Vista
 Visual Studio 2010 Professional
 Expression Studio 4 Ultimate
 (and much, much more)
Creating your first projects
So what are these projects?
There are 2 types of projects that are created out of the box.
 The main project targeting your platform
 This is the starting point of your application. You load assemblies, load media, move
objects from here.
 A content project
 This is where you put all of your assets. XNA supports the following formats out of the box,
but you can build other format importers.
2D graphics: .bmp, .png, .jpg
3D models: .x, .fbx
Shaders: .fx
Audio: .mp3, .wav, .wma
 WP7 requires PCM 16 bit mono/stero
Video: .wmv
Fonts: Any TrueType font
 XNA provides a set of sample high quality fonts (Andy Regular, Kootenay, Lindsey, etc) more info
can be found here
Any XML, text or binary files
 XNA for windows can skip this if you want, but it is required for Xbox and WP7.
 Adding assets to our game
Basic Game Structure
 Initalize: called after the constructor. This
is where you configure all your default
Load Content: Called after Initialize, you
load all assets for your game in here.
Update: This is where you update data,
look for keyboard input, do collision
detection, etc.
Draw: This is where you render your
Unload Content: Once the game exits,
this is where any cleanup would happen.
Basic Game Structure (cont)
What is the GraphicsDeviceManager?
 This is the “graphical context” and is responsible for things
like screen resolution, vertical synchronization, and antialiasing. It also gives you information on hardware
What is a SpriteBatch?
 Simply put, this is what allows you to “draw” 2d images to
the screen. You can draw an entire image to the screen, or
only a small part of the image to a specific area.
 There are no simple polygon “draw” methods. Everything is
handled through textures.
Consistency is the key!
Speeds can vary from computer to computer, or device to
 XNA runs at 60 FPS by default.
 Can be adjusted
IsFixedTimeStep (Bool)
TargetElapsedTime (TimeSpan)
 Use gameTime.ElapsedGameTime to adjust for drift
 Begin
 Tells GPU to draw everything coming to it, in the order
you send it.
 Draw
 0,0 is the top left
 Draw as many textures as possible in each SpriteBatch to
keep speed up
 End
 Do this when done drawing, or when you need to change
drawing settings. (such as AlphaBlend)
Write once, Tweak for platform
 Windows
 Resolution can vary
 Mouse/Keyboard Input
 Xbox
 (640 x 480, 1280 x 720, 1920 x 1080)
 Controllers
 WP7
 480 x 800, 320 x 480
 Touch Screen
 EXTREME memory restrictions.
What’s that? I can’t hear you!
 SoundEffect
 quick sound effects
 Background music loop
 sound.Play();
 Used for quick audio.
 sound.CreateInstance();
 Used for background music loops (allows pausing,
volume adjustments on the fly, etc)
 Add the Background
 Add Paddles
 Add Ball
 Add Score Overlay
 Add Input
Let’s get that ball rolling
 Ball starts in random direction
 +/- X
 +/- Y
 Starts at Width/2, Height/2
 Change X or Y depending on collision
 Y changes based on collision with top or bottom
 X changes based on collision with paddle
 If X < 0 or X > width, then a point is awarded to the
other side
 Animate ball
 Collision detection
 Bounding Box is top left
 Because this is a simple demo, I am using a rectangular
bounding box for collision detection. You should do
more fine grained collision detection for the real deal.
Building for Xbox
 Create new project,
 copy csproj and rename
 Include in project
 “add” appropriate files
 Need creators club account
 Download Xbox Connect app to connect computer to
Xbox for deployment
Building for WP7
 Create new project,
 copy csproj and rename
 Include in project
 “add” appropriate files
 Need windows phone developer account
 Don’t forget to turn off services
 Game hub or app hub?
Further Concerns
 WP7
 Multi-Touch input
 Accelerometer
 Higher Resolution, Smaller Screen
 Tombstoning
 Ram Issues
Applications can use (at most) 90MB of ram on a device with 256MB of
ram. (lowest spec allowed)
If a device has more than 256MB of ram you may use more than 90MB of ram to
the amount of MemorySize – 256MB.
If my device has 512MB of ram, I am allowed to use 512-256 + 90 = 346MB of ram
 Xbox:
 Development requires an Xbox for testing (no emulator)
 What questions do you have?
 Ryan Plemons
 http://digitaltransfusion.net
 @ryanplemons

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