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You learned how to design, create, and use a simple Sprite class. You also learned how to use a generic List object.
This section contains a variety of miscellaneous information.
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Complete listings of the XNA program files discussed in this module are provided in Listing 14 and Listing 15 below.
Listing 14 . Contents of the file named Sprite.cs
/*Project XNA0126Proj
* This file defines a very simple version of a Sprite* class from which multiple Sprite objects can be
* instantiated, loaded with an image, and drawn.* The Position property can be accessed by the user
* to control the position at which the sprite is drawn.*******************************************************/
using System;using Microsoft.Xna.Framework;
using Microsoft.Xna.Framework.Content;using Microsoft.Xna.Framework.Graphics;
namespace XNA0126Proj {class Sprite {
private Texture2D texture;private Vector2 position = new Vector2(0,0);
//-------------------------------------------------//public Vector2 Position {
get {return position;
}set {
position = value;}//end set
}//end Position property accessor//-------------------------------------------------//
//This constructor makes it possible to instantiate// a sprite without assigning an image to the sprite.
public Sprite() {//constructor}//end noarg constructor
//-------------------------------------------------////This constructor makes it possible to assign an
// image to the sprite when it is instantiated.public Sprite(String assetName,
ContentManager contentManager) {texture =
contentManager.Load<Texture2D>(assetName);
}//end constructor//-------------------------------------------------//
//This method makes it possible to assign a new image// to the sprite.
public void SetImage(String assetName,ContentManager contentManager) {
texture =contentManager.Load<Texture2D>(assetName);
}//end SetImage//-------------------------------------------------//
public void Draw(SpriteBatch spriteBatch) {//Call the simplest available version of
// SpriteBatch.DrawspriteBatch.Draw(texture,position,Color.White);
}//end Draw method//-------------------------------------------------//
}//end class}//end namespace Listing 15 . Contents of the file named Game1.cs.
/*Project XNA0126Proj
* This project demonstrates how to design and use a very* simple version of a Sprite class.
** One Sprite object is instantiated in the LoadContent
* method. The object's reference is saved in a generic* List object.
** Twenty-three more Sprite objects are instantiated
* while the game loop is running. A new object is* instantiated every 8th iteration of the game loop
* until 24 objects have been instantiated. Their* references are saved in a generic List object.
** An image of a blueball is stored in 12 of the objects
* and an image of a redball is stored in the other 12* objects.
** The Sprite objects are drawn in a diagonal line in* the game window. The line of Sprite objects moves
* across the game window from upper left to lower right.* The Sprite objects stop moving when they reach the
* bottom right corner of the game window.*
* When the objects stop moving, the image in the* topmost Sprite object is changed from a blueball to a
* greenball.* *****************************************************/
using System;using System.Collections.Generic;
using Microsoft.Xna.Framework;using Microsoft.Xna.Framework.Graphics;
using XNA0126Proj;namespace XNA0126Proj {
public class Game1 : Microsoft.Xna.Framework.Game {GraphicsDeviceManager graphics;
SpriteBatch spriteBatch;//References to the Sprite objects are stored in this
// List object.List<Sprite>sprites = new List<Sprite>();
int maxSprites = 24;//Max number of sprites.int frameCnt = 0;//Game loop frame counter
//This is the limit on the number of frames in which// the sprites are moved.
int moveLim = 200;//-------------------------------------------------//
public Game1() {//constructorgraphics = new GraphicsDeviceManager(this);
Content.RootDirectory = "Content";//Set the size of the game window.
graphics.PreferredBackBufferWidth = 450;graphics.PreferredBackBufferHeight = 450;
}//end constructor//-------------------------------------------------//
protected override void Initialize() {//No initialization required.
base.Initialize();}//end Initialize
//-------------------------------------------------//protected override void LoadContent() {
spriteBatch = new SpriteBatch(GraphicsDevice);//Create the first sprite in the LoadContent
// method using the noarg constructor.sprites.Add(new Sprite());
//Assign an image to the sprite.sprites[0].SetImage("blueball",Content);//More content is loaded in the Update method.
}//end LoadContent//-------------------------------------------------//
protected override void UnloadContent() {//No content unload required.
}//end unloadContent//-------------------------------------------------//
protected override void Update(GameTime gameTime) {//Create remaining sprites in the Update method to
// simulate a game in which sprites come and go as// the game progresses.
if(sprites.Count<(maxSprites)) {
if(frameCnt % 8 == 0) {//Instantiate a new sprite every 8th frame.
if((sprites.Count) % 2 == 0) {//Even numbered sprites
sprites.Add(new Sprite("blueball",Content));}
else {//Odd numbered sprites
sprites.Add(new Sprite("redball",Content));}//end else
}//end if on frameCnt}//end if on sprites.Count
//Make all the sprites move.if(frameCnt<moveLim) {
for(int cnt = 0;cnt<sprites.Count;cnt++) {
sprites[cnt].Position = new Vector2(
10 * cnt + frameCnt,10 * cnt + frameCnt);}//end for loop
}//end if//Change the image on the first sprite at the end
// of the run. Could be used, for example to// change a sprite's image to a fireball in the
// event of a collision.if(frameCnt == moveLim) {
sprites[0].SetImage("greenball",Content);
}//end if//Keep track of the count of the first moveLim
// iterations of the game loop.if(frameCnt<moveLim) {
frameCnt++;}//end if
base.Update(gameTime);}//end Update method
//-------------------------------------------------//protected override void Draw(GameTime gameTime) {
GraphicsDevice.Clear(Color.CornflowerBlue);spriteBatch.Begin();
//Draw all sprites.for(int cnt = 0;cnt<sprites.Count;cnt++) {
sprites[cnt].Draw(spriteBatch);
}//end for loopspriteBatch.End();
base.Draw(gameTime);}//end Draw method
//-------------------------------------------------//}//end class
}//end namespace -end-
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