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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