wp7 hub_xna overview

Windows Phone 7 XNA A different kind of phone, designed for a life in motion

GETTING STARTED WITH XNA

A framework to create game applications

Topics Overview of XNA How games run The XNA Game class Adding and managing game assets Creating and drawing game sprites

XNA XNA is a framework for writing games It includes a set of professional tools for game

production and resource management Windows Phone uses version 4.0 of the framework This is included as part of the Windows Phone SDK

2D and 3D games XNA provides full support for 3D games It allows a game program to make full use of the

underlying hardware acceleration provided by the graphics hardware

For the purpose of this course we are going to focus on 2D gaming

Windows Phone games be either 2D or 3D

5

XNA and Silverlight XNA is completely different from Silverlight The way that programs are constructed and

execute in XNA is quite different XNA has been optimised for game creation

It does not have any elements for user interface or data binding

Instead it has support for 3D rendering and game content management

6

XNA and Programs XNA provides a set of classes which allow you to

create gameplay The classes represent game information and XNA

resources XNA is also a very good example of how you

construct and deploy a set of software resources in a Framework

Creating a Game

The Windows Phone SDK provides a Windows Phone game project type

The Game Project

The solution explorer shows the items that make up our game project

The solution will also contain any content that we add to the game project

Empty Game Display At the moment all our

game does is display a blue screen

This is because the behaviour of the Draw method in a brand new project is to clear the screen to blue

11

Demo 1: New Game

Demo

What a Game Does When it Runs1. Initialise all the resources at the start

fetch all textures, models, scripts etc2. Repeatedly run the game:

1. Update the game world read the user input, update the state and position of game

elements

2. Draw the game world render the game elements on the viewing device

XNA Game Class Methods

partial class PongGame : Microsoft.Xna.Framework.Game

{

protected override void LoadContent

(bool loadAllContent)

{

}

protected override void Update(GameTime gameTime)

{

}

protected override void Draw(GameTime gameTime)

{

}

}

XNA Methods and games Note that our program never calls the LoadContent, Draw and Update methods

They are called by the XNA Framework LoadContent is called when the game starts Draw is called as often as possible Update is called 30 times a second

Note that this is not the same as an XNA game on Windows PC or Xbox, where Update is called 60 times a second

14

Loading Game Content

LoadContent is called when our game starts

It is where we put the code that loads the content into our game

Content includes images, sounds, models etc.

protected override void LoadContent()

{

// Create a new SpriteBatch, which can be used to

// draw textures.

spriteBatch = new SpriteBatch(GraphicsDevice);

}

Game Content Games are not just programs, they also contain

other content: Images for textures and backgrounds Sound Effects 3D Object Meshes

We need to add this content to our project The XNA framework provides a content

management system which is integrated into Visual Studio

Image Resources

This is a Ball image I have saved it as a PNG file

This allows the image to use transparency

You can use any image resource you like

The resources are added to the Visual Studio project

They are held in the Content directory as part of your project

Using the Content Pipeline Each resource is given an

asset name The Load method of

Content Manager provides access to the resource using the Asset Name that we gave it

ballTexture = Content.Load<Texture2D>("WhiteDot");

Storing the Ball Texture in the game

XNA provides a Texture2D type which holds a 2D (flat) texture to be drawn on the display

The game class needs to contain a member variable to hold the ball texture that is to be drawn when the game runs

This variable will be shared by all the methods in the game

// Game World

Texture2D ballTexture;

Loading Content into the Ball Texture

LoadContent is called when a game starts

It loads an image into the ball texture The content manager fetches the

images which are automatically sent to the target device


{

// Create a new SpriteBatch, which can be used to

// draw textures.

spriteBatch = new SpriteBatch(GraphicsDevice);

ballTexture = Content.Load<Texture2D>("WhiteDot");

}

Making a “sprite” A sprite is an object on the screen of a game It has both a texture and a position on the screen We are creating a sprite object for the ball in our

game We now have the texture for the object The next thing to do is position it on the screen

21

Coordinates and Pixels When drawing in XNA the position of an object on

the screen is given using coordinates based on pixels A standard Windows Phone screen is 800 pixels

wide and 480 pixels high This gives the range of possible values for

display coordinates If you draw things off the screen this does not cause

XNA problems, but nothing is drawn

22

X and Y in XNA The coordinate system used by XNA sprite drawing

puts the origin (0,0) in the top left hand corner of the screen Increasing X moves an object across the screen

towards the right Increasing Y moves an object down the screen

towards the bottom It is important that you remember this

23

Positioning the Ball using a Rectangle

We can add a rectangle value to the game to manage the position of the ball on the screen

We will initialise it in the LoadContent method

// Game World


Rectangle ballRectangle;

The Rectangle structure

Rectangle is a struct type which contains a position and a size

The code above creates a rectangle positioned at 0,0 (top left hand corner) the same size as ballTexture

We could move our ball by changing the content of the rectangle

Rectangle ballRectangle = new Rectangle(

0, 0,

ballTexture.Width, ballTexture.Height),

Color.White);

Drawing a Sprite In game programming terms a “sprite” is a texture

that can be positioned on the screen We now have a ball sprite

We have the texture that contains an image of the ball

We have a rectangle that gives the position and size of the sprite itself

26

XNA Game Draw Method

The Draw method is called repeatedly when an XNA game is running It has the job of drawing the display on the

screen A brand new XNA game project contains a Draw

method that clears the screen to CornflowerBlue We must add our own code to the method to draw

the ball


{

GraphicsDevice.Clear(Color.CornflowerBlue);

base.Draw(gameTime);

}

Sprite Batching

2D Graphics drawing is handled by a set of “sprite” drawing methods provided by XNA

These create commands that are passed to the graphics device

The graphics device will not want to draw everything on a piecemeal basis

Ideally all the drawing information, textures and transformations should be provided as a single item

The SpriteBatch class looks after this for us

SpriteBatch Begin and End

The call to the Begin method tells SpriteBatch to begin a assembling a new set of drawing operations

The call to the End method tells SpriteBatch that the there are no more operations and causes the rendering to take place


{


spriteBatch.Begin();

// Code that uses spriteBatch to draw the display

spriteBatch.End();

base.Draw(gameTime);

}

Using SpriteBatch.Draw

The SpriteBatch class provides a Draw method to do the sprite drawing

It is given parameters to tell it what to do: Texture to draw Position (expressed as a Rectangle) Draw color

spriteBatch.Draw(ballTexture, ballRectangle, Color.White);

Rectangle Funnew Rectangle(

0, 0,

ballTexture.Width,

ballTexture.Height)

new Rectangle(

0, 0, // position

200,100) // size

new Rectangle(

50, 50, // position

60, 60) // size

32

Demo 2: Dot Sizes

Demo

Screen Size and Scaling

We need to make our game images fit the size of the screen

We can find out the size of the screen from the GraphicsDevice used to draw it

GraphicsDevice.Viewport.WidthGraphicsDevice.Viewport.Height

We can use this information to scale the images on the screen

Creating the ballRectangle variable

If we use this rectangle to draw our ball texture it will be drawn as a square which is a twentieth of the width of the screen

We can then set the position parts of the rectangle to move the ball around the screen

ballRectangle = new Rectangle(

0, 0,

GraphicsDevice.Viewport.Width / 20,

GraphicsDevice.Viewport.Width / 20);

Moving the ball around the screen At the moment the ball is drawn in the

same position each time Draw runs To move the ball around we need to

make this position change over time We need to give the game an update

behaviour We must add code to the Update

method in the game The Update method is where we

manage the state of the “game world”

The Update Method

The Update method is automatically called 30 times a second when a game is running

It is in charge of managing the “game world” In a pong game this means updating the

bat and the ball positions and checking for collisions


{

// TODO: Add your update logic here

base.Update(gameTime);

}

Simple Update Method

Each time the game updates the X and Y position of the ball rectangle is increased

This will cause it to move across and down the screen

Note that I call the base method to allow my parent object to update too


{

ballRectangle.X++;

ballRectangle.Y++;

base.Update(gameTime);

}

GameTime At the moment the Update method is

called sixty time a second or once every 16.66 milliseconds

We can also let the update "free run", in which case we need to know the time since the last call so we can move objects the right distance

This is what the GameTime parameter is for, it gives the time at which the method was called

39

Demo 2: Moving Dot

Demo

Summary XNA is a Framework of methods that are used to

write games You create the games using Visual Studio Games have initialise, update and draw behaviours Game objects are held as textures objects and their

position and dimensions as rectangle structures

CREATING GAMEPLAY WITH XNA

Topics Controlling the movement of a sprite Creating multiple sprites Using touch input to control sprite movement Detecting sprite collisions Displaying text

XNA and Pong Last time we got a ball to move down the

screen Now we need to make the ball bounce

around the screen Now we need to discover how we can

create paddles and control them using a gamepad or keyboard

Then we can start building a game

Accurate ball positioning

The Rectangle provides integer properties that can be used to position the drawing operation

To get more precise control over the movement of an object we need to use floating point position variables

float ballX = 0;

float ballY = 0;

Accurate ball positioning

The floating point position values are converted to integers to set the position of the draw rectangle

This is performed during the Update method

ballRectangle.X = (int)(ballX + 0.5f);

ballRectangle.Y = (int)(ballY + 0.5f);

Controlling Ball Movement

To manage the speed of the ball we can use a pair of member variables in our game class One for the X speed and one for the Y speed

Each time Update is called these are used to update the values of the X and Y position of the draw rectangle

float ballXSpeed = 3;

float ballYSpeed = 3;

Moving the Ball

The Update method is where the speed values are used to update the rectangle position for the ball

The next call of Draw will draw the ball in the new position

ballX = ballX + ballXSpeed;

ballY = ballY + ballYSpeed;

Going off the Edge

(0,0)

(0,height) (width, height)

(width, 0)

x +texture width > width

x < 0

y < 0

y + texture height > height

Making the Ball Bounce

When the ball reaches the edge of the screen it must change direction

We can do this by reversing the sign of the speed value to reverse the effect of the update

if (ballX < 0 ||

ballX + ballRectangle.Width > GraphicsDevice.Viewport.Width)

{

ballXSpeed = -ballXSpeed;

}

50

Demo 1: Bouncing Ball

Demo

Making a Paddle

The paddle is made from a texture, just like the ball

This time I’ve made a slightly more interesting one which uses transparency

The paddle is loaded as a texture resource, just as the ball is

Game Variables

// Game World


Rectangle ballRectangle;

float ballX;

float ballY;

float ballXSpeed = 3;

float ballYSpeed = 3;

Texture2D lPaddleTexture;

Rectangle lPaddleRectangle;

float lPaddleSpeed = 4;

float lPaddleY; // Repeat these for the right paddle

// Distance of paddles from screen edge

int margin;

Loading GameTextures

When the game starts the LoadContent method is called to load textures and other game assets

We now have three textures in the game


{

ballTexture = Content.Load<Texture2D>("ball");

lPaddleTexture = Content.Load<Texture2D>("lpaddle");

rPaddleTexture = Content.Load<Texture2D>("rpaddle");

// scale the texture draw rectangles here

}

Setting up the paddles

This code positions the paddles on the screen and sets up their sizes

margin = GraphicsDevice.Viewport.Width / 20;

lPaddleRectangle = new Rectangle(

margin, 0,


GraphicsDevice.Viewport.Height / 5);

rPaddleRectangle = new Rectangle(

GraphicsDevice.Viewport.Width –

lPaddleRectangle.Width - margin, 0,


GraphicsDevice.Viewport.Height / 5);

Initial game positions

The LoadContent method puts the paddles and balls at their starting positions as shown above

55

Paddle control We can use the Windows Phone touch screen to

control a paddle The touch screen can track up to four inputs and

can detect when touch events start and end We are just going to test for touches to move the

paddle up or down

56

Getting the Touch Panel status

The TouchPanel class provides a GetState method that will return the touch panel status

This returns a collection of TouchLocation values that describe the present state of the touch panel

This can contain up to four values

TouchCollection touches = TouchPanel.GetState();

Using the Touch information

If we have a touch location we use the position of the touch to move the paddle up or down

if (touches.Count > 0)

{

if (touches[0].Position.Y >

GraphicsDevice.Viewport.Height / 2)

{

lPaddleY = lPaddleY + lPaddleSpeed;

}

else

{

lPaddleY = lPaddleY - lPaddleSpeed;

}

}


If the collection contains some TouchLocation we update the paddle position


{



{


}

else

{


}

}


Get the touch location at the start of the collection


{



{


}

else

{


}

}


Test the Y component of the position of touch against half the height of the screen


{



{


}

else

{


}

}


Move the paddle down if the player touches the bottom half of the screen


{



{


}

else

{


}

}


Move the paddle up if the player touches the top half of the screen


{



{


}

else

{


}

}


Remember that increasing Y moves things down the screen (origin at top left)


{



{


}

else

{


}

}

65

Demo 2: Paddle Control

Demo

Detecting Collisions We need to make the ball bounce off the

paddles when the two collide In the console version of the game we

tested to see if ball and paddle occupied the same part of the screen

In the case of XNA we need to see if the rectangles which control the position of the ball and paddle intersect

Rectangle Intersection

The Rectangle structure provides a method called Intersects which can be used to detect if two rectangles intersect

If the paddle and ball rectangles intersect we must reverse the X direction of movement of the ball to have it bounce off the paddle

if (ballRectangle.Intersects(lPaddleRectangle))

{

ballXSpeed = -ballXSpeed;

}

Completing the Game A finished game must also detect when the

ball reaches the edges of the screen This is when a point has been scored I will leave you to create this code However, you will also need to draw text

on the screen to display messages to the players

This turns out to be very easy

Adding a SpriteFont

A SpriteFont is a content item that lets you draw text on the screen

It provides a set of character designs of a particular size

SpriteFont XML

The font used and the size are set in an XML file You can edit this to get different sizes and styles

Loading a Font

The Content Manager will fetch the font The font can be stored in a variable which a

member of the game class You can use multiple fonts if you want

different text styles

SpriteFont font;


{

// Rest of LoadContent here

font = Content.Load<SpriteFont>("MessageFont");

}

Drawing text

The DrawString method renders a string using the font that has been loaded


{


spriteBatch.Begin();

spriteBatch.DrawString(

font,

"Hello world",

new Vector2(100, 100),

Color.White);

// Rest of Draw here

}

73

Demo 3: Completed Pong Game

Demo

Summary Objects in games can be made to move by updating

their position information It is best if the game manages position in floating

point values The TouchPanel provides a collection of

TouchLocation values that describe touch actions XNA games can draw text using SpriteFonts

GAMES ON WINDOWS PHONE

Topics Using the Accelerometer to control gameplay Playing sounds in XNA games Playing sounds in Silverlight programs Using media in XNA games Windows Phone games and orientation

The Accelerometer The Accelerometer can measure

acceleration in X, Y and Z You can use just the X and Y values to

control sprites in 2D games The values that are returned are in the

range -1 to +1 in each axis When the value is 0 this means the device

is flat on that axis

XNA 4.0 Accelerometer The accelerometer in XNA 4.0 is

event driven The accelerometer generates

events when new readings are available

You must bind a method to the event

The method can store the settings for later use

XNA and Silverlight The reason why the

accelerometer is event driven is that XNA actually uses the same sensor interface as Silverlight

This means that we need to include the appropriate sensor library into our programs to obtain accelerometer readings

Adding the Sensors library

We need to add Microsoft.Devices.Sensors to the solution references to bring in the library

Adding the Namespaceusing Microsoft.Devices.Sensors;

Once you have added the library you can use the Sensors objects

Adding the namespace to your program makes the code a bit cleaner

Note that you only have to do this for the accelerometer

Creating an AccelerometerAccelerometer acc = new Accelerometer();acc.ReadingChanged += new EventHandler<AccelerometerReadingEventArgs> (acc_ReadingChanged);acc.Start();

The above code runs in the Initialise method to set up the accelerometer

Initialise is called by XNA when a game starts

It creates a new Accelerometer, binds an event handler to it and then starts it

running

Accelerometer Events

Vector3 accelState = Vector3.Zero;void acc_ReadingChanged (object sender, AccelerometerReadingEventArgs e){ accelState.X = (float)e.X; accelState.Y = (float)e.Y; accelState.Z = (float)e.Z;}

This method runs when a new reading is available from the accelerometer

It copies the readings into a vector

Using the reading

lPaddleY = lPaddleY - (accelState.X * lPaddleSpeed);

The Pong game only needs to use a single axis

This is the X axis, that runs along the long length of the phone

We have to reverse the sense of the position update as the value of Y

increases down the screen

The accelerometer and orientation The accelerometer provides the same readings

irrespective of the orientation of the device In other words the direction of the axes does not

change when the orientation changes For this reason I would advise you to fix the

orientation of a tipping game

“Tipping” games The accelerometer makes it very easy to

create “tipping” games, which simulate gravity moving items around the screen

The further you tip the device the greater the force acting on the object

This leads to a very simple physics model, which is actually very effective

Demo 1: Tipping Pong game

Demo

Threads and Contention It turns out that there is a potential problem with

the way we are using the accelerometer It is prone to errors caused by the way that we are

using two separate threads of execution to work with the accelerometer values One thread stores the values in the vector The other thread reads the values back

At the moment these threads are not synchronised, and this can cause problems

What might happen…

1. Update runs and reads the X value of the acceleration

2. The Accelerometer event fires and starts running. It generates and stores new values of X, Y and Z

3. Update reads the Y and Z values from the updated values

4. Update now has “scrambled” data

Processes and processors The problem is caused by the way that the

operating system runs multiple processes Each process is given control for a small time

interval and then another is allowed to run If one process is allowed to interrupt another we

can get them “fighting” over data

Adding a Lock We solve the problem by using a “lock” object A process can “grab” the lock object and hold onto

it while it does something that must not be interrupted

At the end of the action it releases the lock object If another process needs to use the lock it will be

paused until the lock becomes available

Accelerometer Events and Lock

object accelLock = new object();void acc_ReadingChanged (object sender, AccelerometerReadingEventArgs e){ lock (accelLock) { accelState.X = (float)e.X; accelState.Y = (float)e.Y; accelState.Z = (float)e.Z; }}

The lock object is just a token which is grabbed and released by the

lock keyword

Accelerometer Events and Lock

lock (accelLock){ lPaddleY = lPaddleY - (accelState.X * lPaddleSpeed);}

In the Update method the statement that uses the accelerometer

reading is protected by a lock

This means that it is not possible for the reading process to be

interrupted

Locks and Programs The locking behaviour is provided by the operating

system A process that cannot run because it is waiting for a

lock will be held until it can It is important that code that uses a lock does not

take a long time to complete This might cause other processes to get stuck

waiting for the lock to become available

“Deadly Embrace” It is also important that two processes don’t each

end up waiting for a lock the other has This causes both processes to be stuck You can do this by making a process either

“produce” or “consume” data You only tend to get deadly embraces when a

process is both a producer and a consumer

Sounds as Content XNA uses a Content Manager to look after

the resources used by a game Each content type has a “pipeline” of

processors that bring it into the project and then package it for inclusion in the game distributable

You don’t need to worry how this works You can write your own content library if you

wish

XNA Sound Types

Sound effects wav files held in memory for quick

playback Background music

wma and mp3 files loaded and played

Managed as media (more on this later)

Preparing Sounds

A good tool for preparing sound files is Audacity

It will also convert between mp3 and wav format

You can download it for free fromhttp://audacity.sourceforge.net/

Adding Content

The simplest way to add content is to drag and drop it into the solution

You can place it alongside images, or in separate folders

Content Properties

The content Properties pane identifies the asset name and the importer to use

SoundEffect variables

// Sound effectsSoundEffect dingSound;SoundEffect explodeSound;

These game member variables hold the sound effects for the “Pong” game

They will be initialised with content when the game starts running

We do this in LoadContent method does this

The LoadContent method

protected override void LoadContent(){ // rest of LoadContent here dingSound = Content.Load<SoundEffect>("ding"); explodeSound = Content.Load<SoundEffect>("explode");}

LoadContent is called when the game starts

The game contains a Content Manager which manages game content (surprisingly)

The Load method uses Generics to determine the required loader

Simple Sound Playback

if (ballY < 0 || ballY + ballRectangle.Height > GraphicsDevice.Viewport.Height){ ballYSpeed = -ballYSpeed; dingSound.Play();}

An instance of the SoundEffect class provides a Play method that plays the sound

instantly

The Pong game will play the ding sound when the ball hits the top or bottom of the

screen

Complex Sound Playback Sometimes the sound playback is more

complex We might want to play an engine sound

continuously when the “engine” is running We might also want to vary the pitch of the

sound as it plays To do this we use a SoundEffectInstance This is an object that serves as a handle to a

playing sound

The SoundEffectInstance

engineInstance = engineSound.CreateInstance();

When we call the Play method on a sound effect this is a “fire and forget” kind of sound

playback

To get more control over a sound we need to create an object that represents it

A SoundEffect can be asked to create an object representing an instance of a sound being

played by using the CreateInstance method

Playing Sounds

engineInstance.Play();...engineInstance.Pause();...engineInstance.Stop();

The Play method on a SoundEffectInstance will start sound playback

We can also call Pause and Stop to control the sound

Controlling Volume

engineInstance.Volume = accelVector.Length() / volFactor;

The Volume property lets you adjust the volume of a playing sound

The range is from 0 to 1:

0 no sound

+1 maximum volume

Controlling Pitch

engineInstance.Pitch = accelVector.Length() / soundFactor;

The Pitch property lets you adjust the pitch of a playing sound

The range is from -1 to 1:

-1 octave low

0 normal pitch

+1 octave high

Controlling Position

engineInstance.Pan = cheesePan;

The Pan property lets you adjust the pan position of a playing sound

The range is from -1 to 1:

-1 hard left

0 center

+1 right

Sound Status

1. if (engineInstance.State == SoundState.Stopped)2. {3. engineInstance.Play();4. }

The SoundEffectInstance exposes a property that gives the playing status

This is updated when the sound stops playing

The code above will play the sound again if it is stopped

This is a primitive kind of looping

Looping Sounds

engineInstance.IsLooped = true;

I can get the looping effect by simply restarting playback from the

SoundEffectInstance each time the game detects that it has stopped

However, there is a much easier way of getting this effect

I simply set the IsLooped property to true

Demo 2: Games with Sounds

Demo

Silverlight and XNA If you want to play sound effects in a

Silverlight program you use the XNA SoundEffect class

The process is as follows: Add XNA to a Silverlight game Load the sound effect from a

resource Play the sound effect as with XNA Keep the XNA system updated

114

Adding XNA to a Silverlight Game

The first thing to do is add the reference to the XNA Framework to the solution

You might get a warning when you do this, but it is OK

115

Adding XNA to a Silverlight Game

Next you add the namespaces so you can easily use the objects

116

Adding Sound Resources Now you can add

the sound itself These are stored

as items of content in the solution wav files work

well Create a folder in

your solution to keep things tidy

117

Adding Sound Resources

Now you need to set the properties of the sound item

Make sure the build action is set to Content

118

Loading a SoundEffect

Beep = SoundEffect.FromStream(TitleContainer.OpenStream("Sounds/beep.wav"));

This code runs at the start of the game

It creates a SoundEffect value from the sound resources

This mechanism is used in Silverlight because there is no Content Manager for a Silverlight

application

119

Playing a SoundEffect

beep.Play();

The Play method works in exactly the same was as in XNA

If you want more control of the sound playback you can create and use

SoundEffectInstance values to control a sound during playback

120

Keeping XNA Awake

The XNA framework is driven by repeated calls of Draw and Update methods

In Silverlight these do not happen

We need to update XNA to allow sound playback

The FrameworkDispatcher.Update() method must be called at regular intervals to keep

XNA sound working

The best way to do this is to create a timer

121

Creating a Timer

using System.Windows.Threading;

DispatcherTimer timer = new DispatcherTimer();timer.Tick += new EventHandler(timer_Tick);timer.Interval = TimeSpan.FromTicks(333333);timer.Start();

A DispatcherTimer is a timer that runs in the same thread as the Silverlight page

We can create one that fires at the same rate as XNA, 30 times a second

We can also bind a method to the tick event

122

The Timer Tick event handler

void timer_Tick(object sender, EventArgs e){ FrameworkDispatcher.Update();}

When the timer ticks it just updates the XNA framework to keep sound playback working

correctly

You can also use this technique to animate Silverlight displays

Demo 3: Silverlight with Sound

Demo

Orientation

Windows Phone games can be played in many orientations

By default the game is configured for landscape orientation

Forcing Game Orientation

You can force a particular orientation by setting the size of the back buffer

This works by using the scaling hardware in the Windows Phone display

The Magical Scaler The scaler uses hardware, so your game

is not slowed down by it It interpolates to make the scaling

look good It scales from 240x240 to 800x480 (or

480x800) It will add a letterbox (black bars) if the

chosen aspect ratio doesn’t match the hardware

Viewport properties and touch input positions in your program always match the scaled screen

Selecting Orientations

Your game can indicate which orientations it can support

The game above can support anything!

Detecting Changes

There is an event you can bind to if you need to detect orientation changes

Using the full screen

The Windows Phone uses the top of the screen for status information

This is not always displayed, but when an XNA game runs this space is always reserved for the status information

You can see this if you change the theme background to Light

Using the Full Screen

If you ask to use the full screen this will hide the status bar

You can do this in the Initialize method for your game

XNA games and the Lock Screen The user of the phone can configure a

Screen time-out value in the lock & wallpaper screen

This will time the screen out after a given interval if no user input is detected

The system checks for user input from the touch screen and the hardware buttons It does not test the accelerometer

This means that games that are accelerometer controlled are liable to be timed out

Disabling the screen timeout

This statement disables the screen timeout

Your game will now run uninterrupted You should use this with care however

The game is now in a position to run until the phone battery goes flat

You can re-enable the timeout by setting the property to true

Guide.IsScreenSaverEnabled = false;

Summary The Windows Phone supports gameplay in multiple

orientations which you can set in your game code The accelerometer allows games to be controlled by

tipping the phone XNA and Silverlight can play back sound XNA programs can access the media library in the

phone

EXERCISE 1: USE MULTI-TOUCH IN A WINDOWS PHONE GAME

EXERCISE 2: USE THE ACCELEROMETER IN AN XNA PROGRAM

wp7 hub_xna overview

Education

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game program

game startsit

game production

game worldrender

game assetscreating

game information

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