Android实战打飞机游戏之无限循环的背景图(2)

首先分析下游戏界面内的元素：
无限滚动的背景图, 可以操作的主角,主角的子弹, 主角的血量,两种怪物(敌机),一个boss, boss的爆炸效果.

先看效果图

1、首先实现无限滚动的背景图 原理: 定义两个位图对象 当第一个位图到末尾是 第二个位图从第一个位图的末尾跟上.

public class GameBg {
 // 游戏背景的图片资源
 // 为了循环播放，这里定义两个位图对象，
 // 其资源引用的是同一张图片
 private Bitmap bmpBackGround1;
 private Bitmap bmpBackGround2;

 // 游戏背景坐标
 private int bg1x, bg1y, bg2x, bg2y;

 private int speed = 3;

 public GameBg(Bitmap bmpBackGround) {
  this.bmpBackGround1 = bmpBackGround;
  this.bmpBackGround2 = bmpBackGround;
  // 首先让第一张填满屏幕
  bg1y = -Math.abs(bmpBackGround.getHeight() - MySurfaceView.screenH);

  bg2y = bg1y - bmpBackGround1.getHeight() +50;
 }

 public void draw(Canvas canvas,Paint paint){

  canvas.drawBitmap(bmpBackGround1, bg1x, bg1y, paint);
  canvas.drawBitmap(bmpBackGround2, bg2x, bg2y, paint);
 }
 public void logic(){
  bg1y +=speed;
  bg2y +=speed;

  if(bg1y > MySurfaceView.screenH){
   bg1y = bg2y - bmpBackGround1.getHeight() +50;
  }
  if(bg2y > MySurfaceView.screenH){
   bg2y = bg1y - bmpBackGround1.getHeight() +50;
  }
 }

}

然后再在MySurfaceview里面调用方法

public class MySurfaceView extends SurfaceView implements Callback, Runnable {
 private SurfaceHolder sfh;
 private Paint paint;
 private Thread th;
 private boolean flag;
 private Canvas canvas;

 // 1 定义游戏状态常量
 public static final int GAME_MENU = 0;// 游戏菜单
 public static final int GAMEING = 1;// 游戏中
 public static final int GAME_WIN = 2;// 游戏胜利
 public static final int GAME_LOST = 3;// 游戏失败
 public static final int GAME_PAUSE = -1;// 游戏菜单
 // 当前游戏状态(默认初始在游戏菜单界面)
 public static int gameState = GAME_MENU;
 // 声明一个Resources实例便于加载图片
 private Resources res = this.getResources();
 // 声明游戏需要用到的图片资源(图片声明)
 private Bitmap bmpBackGround;// 游戏背景
 private Bitmap bmpBoom;// 爆炸效果
 private Bitmap bmpBoosBoom;// Boos爆炸效果
 private Bitmap bmpButton;// 游戏开始按钮
 private Bitmap bmpButtonPress;// 游戏开始按钮被点击
 private Bitmap bmpEnemyDuck;// 怪物鸭子
 private Bitmap bmpEnemyFly;// 怪物苍蝇
 private Bitmap bmpEnemyBoos;// 怪物猪头Boos
 private Bitmap bmpGameWin;// 游戏胜利背景
 private Bitmap bmpGameLost;// 游戏失败背景
 private Bitmap bmpPlayer;// 游戏主角飞机
 private Bitmap bmpPlayerHp;// 主角飞机血量
 private Bitmap bmpMenu;// 菜单背景
 public static Bitmap bmpBullet;// 子弹
 public static Bitmap bmpEnemyBullet;// 敌机子弹
 public static Bitmap bmpBossBullet;// Boss子弹
 public static int screenW;
 public static int screenH;

 //
 private GameMenu gameMenu;
 private GameBg gameBg;

 /**
  * SurfaceView初始化函数
  */
 public MySurfaceView(Context context) {
  super(context);
  sfh = this.getHolder();
  sfh.addCallback(this);
  paint = new Paint();
  paint.setColor(Color.WHITE);
  paint.setAntiAlias(true);
  setFocusable(true);
 }

 /**
  * SurfaceView视图创建，响应此函数
  */
 @Override
 public void surfaceCreated(SurfaceHolder holder) {
  screenW = this.getWidth();
  screenH = this.getHeight();
  initGame();
  flag = true;
  // 实例线程
  th = new Thread(this);
  // 启动线程
  th.start();
 }

 /**
  * 加载游戏资源
  */
 private void initGame() {
  // 加载游戏资源
  bmpBackGround = BitmapFactory
    .decodeResource(res, R.drawable.background);
  bmpBoom = BitmapFactory.decodeResource(res, R.drawable.boom);
  bmpBoosBoom = BitmapFactory.decodeResource(res, R.drawable.boos_boom);
  bmpButton = BitmapFactory.decodeResource(res, R.drawable.button);
  bmpButtonPress = BitmapFactory.decodeResource(res,
    R.drawable.button_press);
  bmpEnemyDuck = BitmapFactory.decodeResource(res, R.drawable.enemy_duck);
  bmpEnemyFly = BitmapFactory.decodeResource(res, R.drawable.enemy_fly);
  bmpEnemyBoos = BitmapFactory.decodeResource(res, R.drawable.enemy_pig);
  bmpGameWin = BitmapFactory.decodeResource(res, R.drawable.gamewin);
  bmpGameLost = BitmapFactory.decodeResource(res, R.drawable.gamelost);
  bmpPlayer = BitmapFactory.decodeResource(res, R.drawable.player);
  bmpPlayerHp = BitmapFactory.decodeResource(res, R.drawable.hp);
  bmpMenu = BitmapFactory.decodeResource(res, R.drawable.menu);
  bmpBullet = BitmapFactory.decodeResource(res, R.drawable.bullet);
  bmpEnemyBullet = BitmapFactory.decodeResource(res,
    R.drawable.bullet_enemy);
  bmpBossBullet = BitmapFactory
    .decodeResource(res, R.drawable.boosbullet);

  //菜单类实例化
  gameMenu = new GameMenu(bmpMenu, bmpButton, bmpButtonPress);

  gameBg = new GameBg(bmpBackGround);

 }

 /**
  * 游戏绘图
  */
 public void myDraw() {
  try {
   canvas = sfh.lockCanvas();
   if (canvas != null) {
    canvas.drawColor(Color.WHITE);
    // 绘图函数根据游戏状态不同进行不同绘制

    switch (gameState) {
    case GAME_MENU:

     gameMenu.draw(canvas, paint);
     break;
    case GAMEING:
     gameBg.draw(canvas, paint);
     break;

    case GAME_WIN:

     break;
    case GAME_LOST:

     break;
    case GAME_PAUSE:
     break;
    default:
     break;
    }

   }
  } catch (Exception e) {
   // TODO: handle exception
  } finally {
   if (canvas != null)
    sfh.unlockCanvasAndPost(canvas);
  }
 }

 /**
  * 触屏事件监听
  */
 @Override
 public boolean onTouchEvent(MotionEvent event) {
  switch (gameState) {
  case GAME_MENU:

   gameMenu.onTouchEvent(event);
   break;
  case GAMEING:
   break;

  case GAME_WIN:

   break;
  case GAME_LOST:

   break;
  case GAME_PAUSE:

   break;
  }
  return true;
 }

 /**
  * 按键事件监听
  */
 @Override
 public boolean onKeyDown(int keyCode, KeyEvent event) {
  switch (gameState) {
  case GAME_MENU:

   break;
  case GAMEING:
   break;

  case GAME_WIN:

   break;
  case GAME_LOST:

   break;
  case GAME_PAUSE:
   break;
  }
  return super.onKeyDown(keyCode, event);
 }

 @Override
 public boolean onKeyUp(int keyCode, KeyEvent event) {
  switch (gameState) {
  case GAME_MENU:

   break;
  case GAMEING:
   break;

  case GAME_WIN:

   break;
  case GAME_LOST:

   break;
  case GAME_PAUSE:
   break;
  }
  return super.onKeyUp(keyCode, event);
 }

 /**
  * 游戏逻辑
  */
 private void logic() {
  switch (gameState) {
  case GAME_MENU:

   break;
  case GAMEING:
   gameBg.logic();
   break;

  case GAME_WIN:

   break;
  case GAME_LOST:

   break;
  case GAME_PAUSE:
   break;
  }

 }

 @Override
 public void run() {
  while (flag) {
   long start = System.currentTimeMillis();
   myDraw();
   logic();
   long end = System.currentTimeMillis();
   try {
    if (end - start < 50) {
     Thread.sleep(50 - (end - start));
    }
   } catch (InterruptedException e) {
    e.printStackTrace();
   }
  }
 }

 /**
  * SurfaceView视图状态发生改变，响应此函数
  */
 @Override
 public void surfaceChanged(SurfaceHolder holder, int format, int width,
   int height) {
 }

 /**
  * SurfaceView视图消亡时，响应此函数
  */
 @Override
 public void surfaceDestroyed(SurfaceHolder holder) {
  flag = false;
 }
}

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