1. Gameprogrammeren: Game states
Arjan Egges
Paul Bergervoet
Wouter van Toll

2. Game states Veel games hebben verschillende game toestanden Hoofdmenu
Optiemenu
Helpmenu
Aan het spelen
Game over
Highscore …

3. goede klassenstructuur!
Game states
Noemen we ook wel: Game states
Hoe representeren we die toestanden?
Hoe wisselen we tussen toestanden?
Maak gebruik van een
goede klassenstructuur!

4. Ad hoc manier in Jewel Jam
public override void HandleInput(InputHelper inputHelper) {
if (title.Visible) {
if (inputHelper.KeyPressed(Keys.Space))
title.Visible = false; }
else if (this.GameOver)
this.Reset();
else
...
Per game state andere
invoer afhandelen.

5. Ad hoc manier in Jewel Jam
Zelfde idee in Update.
public override void Update(GameTime gameTime) {
if (this.GameOver && !gameover.Visible)
gameover.Visible = true;
JewelJam.AssetManager.playSound("snd_gameover"); }
else if (!helpFrame.Visible && !title.Visible)
base.Update(gameTime);
Kan tot verwarring leiden!

6. Algemeen game loop object
Definieer een interface met daarin alle belangrijke game loop methoden.
interface IGameLoopObject {
void HandleInput(InputHelper inputHelper);
void Update(GameTime gameTime);
void Draw(GameTime gameTime, SpriteBatch spriteBatch);
void Reset(); }

7. Klassen implementeren de interface
Ook de GameObject klasse!
class GameObject : IGameLoopObject {
protected GameObject parent;
protected Vector2 position, velocity;
protected int layer;
protected string id;
protected bool visible;
... }

8. Game state manager class GameStateManager : IGameLoopObject {
protected Dictionary<string, IGameLoopObject> gameStates;
protected IGameLoopObject currentGameState;
public GameStateManager()
gameStates = new Dictionary<string, IGameLoopObject>();
currentGameState = null; }
...

9. Game state manager
public void AddGameState(string name, IGameLoopObject state) {
gameStates[name] = state; }
public IGameLoopObject GetGameState(string name)
return gameStates[name];
public IGameLoopObject CurrentGameState
get
return currentGameState;

10. public void SwitchTo(string name){
if (gameStates.ContainsKey(name))
currentGameState = gameStates[name]; }

11. Game state manager public void HandleInput(InputHelper inputHelper) {
if (currentGameState != null)
currentGameState.HandleInput(inputHelper); }
public void Update(GameTime gameTime) {
currentGameState.Update(gameTime);
public void Draw(GameTime gameTime, SpriteBatch spriteBatch) {
currentGameState.Draw(gameTime, spriteBatch);
...

12. In PenguinPairs Static membervariabele: Met property:
protected static GameStateManager gameStateManager;
public static GameStateManager GameStateManager {
get { return gameStateManager; } }

13. class TitleMenuState : GameObjectList {
protected Button playButton, optionButton, helpButton;
public TitleMenuState() {
// create the game objects... }
public override void HandleInput(InputHelper inputHelper) {
base.HandleInput(inputHelper);
if (playButton.Pressed)
PenguinPairs.GameStateManager.SwitchTo("levelMenu");
else if (optionButton.Pressed)
PenguinPairs.GameStateManager.SwitchTo("optionsMenu");
else if (helpButton.Pressed)
PenguinPairs.GameStateManager.SwitchTo("helpState");

14. class OptionsMenuState : GameObjectList {
protected Button backButton;
protected Slider musicVolumeSlider;
protected OnOffButton onOffButton;
public override void HandleInput(InputHelper inputHelper) {
base.HandleInput(inputHelper);
if (backButton.Pressed)
PenguinPairs.GameStateManager.SwitchTo("titleMenu"); }
public override void Update(GameTime gameTime) {
base.Update(gameTime);
MediaPlayer.Volume = musicVolumeSlider.Value;
...

15. In PenguinPairs protected override void LoadContent() {
spriteBatch = new SpriteBatch(GraphicsDevice);
screen = new Point(1200, 900);
this.SetFullScreen(false);
gameStateManager.AddGameState("titleMenu",
new TitleMenuState());
gameStateManager.AddGameState("optionsMenu",
new OptionsMenuState());
gameStateManager.AddGameState("levelMenu",
new LevelMenuState());
gameStateManager.AddGameState("helpState",
new HelpState());
gameStateManager.SwitchTo("titleMenu"); }

16. In PenguinPairs protected void HandleInput() { inputHelper.Update();
if (inputHelper.KeyPressed(Keys.Escape))
this.Exit();
if (inputHelper.KeyPressed(Keys.F5))
SetFullScreen(!graphics.IsFullScreen);
gameStateManager.HandleInput(inputHelper); }

17. In PenguinPairs protected override void Update(GameTime gameTime) {
HandleInput();
gameStateManager.Update(gameTime); }
protected override void Draw(GameTime gameTime)
GraphicsDevice.Clear(Color.Black);
spriteBatch.Begin(SpriteSortMode.Deferred, null, null, null, null,
null, spriteScale);
gameStateManager.Draw(gameTime, spriteBatch);
spriteBatch.End();