1. Animated Sprites

2. Class-Level Variables
GraphicsDeviceManager graphics;
SpriteBatch spriteBatch;
Texture2D panobkg;
Rectangle bkg;
Vector2 bkgpos;
Vector2 bkgorigin;
Vector2 homerpos;
KeyboardState keystate;
Rectangle homer;
Texture2D homersprite;
Random rnd = new Random();
float homerflip;
Vector2 homercenter = new Vector2(28, 43);
int homercount;
int jumpcount;
int mshomer = 60;
int msdel;
double y;
int ybase;
double vy;
double ay = -0.1;
SoundEffect woohoo;
SoundEffect scream;
SoundEffect doh;
homer animation rate (60 milliseconds per frame)

3. SpriteSheet for Animated Sprites
742 x 174
174/2 = 87
742/13 = 57

4. size of blit in spritesheet
protected override void Initialize() {
base.Initialize();
bkgpos.X = 0;
bkgpos.Y = 0;
graphics.PreferredBackBufferWidth = 800;
graphics.PreferredBackBufferHeight = 348;
bkg = new Rectangle(0, 0, graphics.PreferredBackBufferWidth, graphics.PreferredBackBufferHeight);
bkgorigin.X = 0;
bkgorigin.Y = 0;
graphics.ApplyChanges();
homer.X = 0;
homer.Y = 0;
homer.Width = 57;
homer.Height = 87;
homercount = 6;
jumpcount = 0;
homerflip = 0;
msdel = 0;
homerpos.X = graphics.PreferredBackBufferWidth / 2;
homerpos.Y = graphics.PreferredBackBufferHeight - 63;
ybase = (int)homerpos.Y;
vy = 0.0; }
size of blit in spritesheet

5. Homer Running msdel += gameTime.ElapsedGameTime.Milliseconds;
keystate = Keyboard.GetState();
if (keystate.IsKeyDown(Keys.Right)) {
homer.Y = 0;
if (homerpos.X < bkg.Width / )
homerpos.X += 4;
else
bkg.X += 4;
if (bkg.X >= panobkg.Width - bkg.Width)
if (msdel > mshomer)
homercount -= 1;
msdel = 0;
if (homercount < 0)
homercount = 5; }
if (keystate.IsKeyDown(Keys.Left)) {
homer.Y = 87;
if (homerpos.X > bkg.Width / )
homerpos.X -= 4;
else
bkg.X -= 4;
if (bkg.X <= 0)
if (msdel > mshomer)
homercount -= 1;
msdel = 0;
if (homercount < 0)
homercount = 5; }

6. Scrolling Background location of homer in world coordinates
if (keystate.IsKeyUp(Keys.Right) && keystate.IsKeyUp(Keys.Left) && jumpcount == 0)
homercount = 6;
if (homerflip > 0)
homerflip += (float)0.6;
if (homerflip > 25)
homerflip = 0;
homer.X = (homercount + jumpcount) * 57;
if (homerpos.X > bkg.Width - 35)
homerpos.X = bkg.Width - 35;
if (homerpos.X < 35)
homerpos.X = 35;
if (bkg.X < 0)
bkg.X = 0;
if (bkg.X > panobkg.Width - bkg.Width)
bkg.X = panobkg.Width - bkg.Width;
location of homer in world coordinates
scrolling in background

8. Homer Jumping if (keystate.IsKeyDown(Keys.Up) && jumpcount == 0) {
vy = 1.3;
jumpcount = 7;
homercount = 0;
woohoo.Play(); }
if (jumpcount > 0)
vy += ay;
y += vy + ay / 2.0;
homerpos.Y -= (int)y;
if (homerpos.Y > ybase)
homerpos.Y = ybase;
jumpcount = 0;
vy = 0.0;
y = 0.0;

9. location sprite is being drawn size of sprite blit
protected override void Draw(GameTime gameTime) {
GraphicsDevice.Clear(Color.CornflowerBlue);
spriteBatch.Begin();
spriteBatch.Draw(panobkg, bkgorigin, bkg, Color.White, 0, bkgorigin, 1, 0, 1);
spriteBatch.Draw(homersprite, homerpos, homer, Color.White, homerflip, homercenter, 2, 0, 0);
spriteBatch.End();
base.Draw(gameTime); }
source of sprite image
location sprite is being drawn
size of sprite blit
sprite rotation angle
center of rotation