Creating a Game World - Learning C# by Programming Games - page 47

using Microsoft.Xna.Framework;

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using Microsoft.Xna.Framework.Graphics; 2

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4 class DiscoWorld : Game

{

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GraphicsDeviceManager graphics;

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SpriteBatch spriteBatch;

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Color background;

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10 static void Main()

{

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DiscoWorld game = new DiscoWorld();

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game.Run(); 13

}

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public DiscoWorld()

{

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Content.RootDirectory = "Content"; 18

graphics = new GraphicsDeviceManager( this );

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}

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22 protected override void LoadContent()

{ 23

spriteBatch = new SpriteBatch(GraphicsDevice);

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}

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27 protected override void Update(GameTime gameTime)

{ 28

int red = gameTime.TotalGameTime.Milliseconds;

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background = new Color(red, 0, 0);

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} 31

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33 protected override void Draw(GameTime gameTime)

{ 34

GraphicsDevice.Clear(background);

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}

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}

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Listing 4.1 A program that displays a changing background color

you can see in Listing 4.1 ,the Draw method has a parameter of type GameTime , and
the name of this parameter is gameTime . Inside the method, we can use the param-
eter just like we use a variable. So, when we are executing instructions inside the
Draw method, the current game time is stored somewhere in the memory, and we can
access it with the name gameTime . The type of this parameter is GameTime , which is
a much more complicated type than an integer. In fact, the GameTime type consists