Question

I’m a complete newbie at XNA and I am currently learning from this tutorial:

http://msdn.microsoft.com/en-us/library/bb203893.aspx

The problem occurs when running the program after completion of step five. I don’t think it’s a typo as others have pointed out the same problem in the comments.

My sprite is meant to bounce around the screen automatically when my program is run, however is does not move even a pixel from 0,0.

using System;
using System.Collections.Generic;
using System.Linq;
using Microsoft.Xna.Framework;
using Microsoft.Xna.Framework.Audio;
using Microsoft.Xna.Framework.Content;
using Microsoft.Xna.Framework.GamerServices;
using Microsoft.Xna.Framework.Graphics;
using Microsoft.Xna.Framework.Input;
using Microsoft.Xna.Framework.Media;

namespace WindowsGame1
{

public class Game1 : Microsoft.Xna.Framework.Game
{
    GraphicsDeviceManager graphics;
    SpriteBatch spriteBatch;

    public Game1()
    {
        graphics = new GraphicsDeviceManager(this);
        Content.RootDirectory = "Content";
    }


    protected override void Initialize()
    {


        base.Initialize();
    }

    Texture2D myTexture;

    Vector2 spritePosition = Vector2.Zero;

    Vector2 spriteSpeed = new Vector2(50.0f, 50.0f);

    protected override void LoadContent()
    {

        spriteBatch = new SpriteBatch(GraphicsDevice);
        myTexture = Content.Load<Texture2D>("Main");

    }


    protected override void UnloadContent()
    {

    }


     void UpdateSprite(GameTime gameTime)
    {
        //Move the sprite by speed, scaled by elapsed time

         spritePosition +=
            spriteSpeed * (float)gameTime.ElapsedGameTime.TotalSeconds;

        int MaxX =
            graphics.GraphicsDevice.Viewport.Width - myTexture.Width;
         int MinX = 0;

         int MaxY =
             graphics.GraphicsDevice.Viewport.Height - myTexture.Height;
         int MinY = 0;

         //Check for bounce.
         if (spritePosition.X > MaxX)
         {
             spriteSpeed.X *= -1;
             spritePosition.X = MaxX;

         }

         else if (spritePosition.X < MinX)
         {
             spriteSpeed.X *= -1;
             spritePosition.X = MinX;

         }

         if (spritePosition.Y > MaxY)
         {
             spriteSpeed.Y *= -1;
             spritePosition.Y = MaxY;
         }

         else if (spritePosition.Y < MinY)
         {
             spriteSpeed.Y *= -1;
             spritePosition.Y = MinY;
         }


    }


    protected override void Draw(GameTime gameTime)
    {
        GraphicsDevice.Clear(Color.CornflowerBlue);



        spriteBatch.Begin(SpriteSortMode.BackToFront, BlendState.AlphaBlend);
        spriteBatch.Draw(myTexture, spritePosition, Color.White);
        spriteBatch.End();

        base.Draw(gameTime);
    }
  }
}

Answer 1

UpdateSprite method is not called from anywhere…

You should override the Update method and call your UpdateSprite method from there…

EDIT:

Add this to your game class:

protected override void Update(GameTime gameTime)
{
    UpdateSprite(gameTime);
}