launch_missiles.java

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      default :
        say_pos_x = say_margin ;
        break ;
    }
    Graphics bg = buffer.getGraphics() ;
    bg.setFont(say_font) ;
    if (say_style == SHADOW) {
      bg.setColor(new Color(150,150,150)) ;
      bg.drawString(s, say_pos_x+2,say_pos_y+1) ;
    }
    bg.setColor(Color.white) ;            // 在缓冲区内写字符串
    bg.drawString(s, say_pos_x,say_pos_y) ;
    say_pos_y += (int) (1.2 * fm.getHeight()) ;         // 提升相应的 y坐标值
    bg.dispose() ;                              // 释放资源
  }
  public void set_say_mode(int m) {       // 设置显示模式
    say_mode = m ;
  }
  public void set_say_style(int s) {        // 设置显示类型
    say_style = s ;
  }
  public void set_say_font(Font f) {        // 设置显示所用的字体
    say_font = f ;
  }
  public void set_say_margin(int margin) {        // 设置显示的空白边缘
    say_margin = margin ;
  }
  public void set_say_pos(int x, int y) {     // 设置显示位置的坐标
    say_pos_x = x ;
    say_pos_y = y ;
  }
}

/* --------------------  定义Piece基类 -------------------------- */

class Piece {
  Launch_Missiles a ;
  int px,py ; // 定义新位置的x、y坐标
  int opx,opy ; // 定义旧位置的x、y坐标
  int w,h ; // 定义宽度，高度
  int vx,vy ; // 定义x和y方向的速度
  Color c ; // 定义颜色
  boolean active = false ;
  Image img = null ;
  public void set_pos(int x, int y) {    // 设定位置
    px = opx = x ;
    py = opy = y ;
  }
  public void set_vel(int x,int y) {  // 设置速度
    vx = x ;
    vy = y ;
  }
  public void set_size(int x,int y) {    // 设置高度和宽度
    w = x ;
    h = y ;
  }
  public void set_color(Color c) {    // 设置颜色
    this.c = c ;
  }
  public void set_draw_rectangles(Rectangle o, Rectangle n) {    // 设置绘制区域
    int sh = a.window_size.height ;
    int x  = px - w/2 ;
    int y  = (sh - py) - h/2 ;
    int ox = opx - w/2 ;
    int oy = (sh - opy) - h/2 ;
    o.setBounds(ox,oy,w,h);
    n.setBounds(x,y,w,h) ;
  }
  public boolean active() {    // 获取active属性值
    return active ;
  }
  public void active(boolean s) {    // 设置active属性值
    active = s ;
  }
  public boolean collision(Piece p) {    // 物体间的碰撞的监测
    int dpx = Math.abs(px - p.px) ;
    int dpy = Math.abs(py - p.py) ;
    if ((dpx < (Math.max(w/2,p.w/2))+1) && (dpy < (Math.max(h/2,p.h/2)+1)))
      return true ;
    return false ;
  }
  public void draw() {    // 绘制对象
    set_draw_rectangles(a.paint_area, a.new_area) ;      // 设置绘制的区域
    Graphics bg = a.buffer.getGraphics() ;      // 绘制缓冲区
    bg.clipRect(a.paint_area.x, a.paint_area.y, w, h);
    bg.drawImage(a.backdrop,0,0,a) ;
    bg.dispose() ;
    a.buf_g.setColor(c);      // 填充缓冲区
    a.buf_g.fillRect(a.new_area.x, a.new_area.y, w, h);
    a.paint_area.add(a.new_area) ;      // 使用新的区域
    Graphics g = a.getGraphics() ;      // 将缓冲绘制到屏幕上
    g.clipRect(a.paint_area.x ,a.paint_area.y, a.paint_area.width, a.paint_area.height);
    g.drawImage(a.buffer, 0, 0, a);
    g.dispose() ;
  }
  public void erase() {    // 清除
    set_draw_rectangles(a.paint_area, a.new_area) ;      // 设置绘制的区域
    a.paint_area.add(a.new_area) ;      // 使用新的区域
    Graphics bg = a.buffer.getGraphics() ;      // 将背景幕拷到缓冲中
    bg.clipRect(a.paint_area.x, a.paint_area.y, a.paint_area.width, a.paint_area.height);
    bg.drawImage(a.backdrop,0,0,a) ;
    bg.dispose() ;
    Graphics g = a.getGraphics() ;      // 将缓冲绘制到屏幕上
    g.clipRect(a.paint_area.x,a.paint_area.y,a.paint_area.width,a.paint_area.height);
    g.drawImage(a.buffer,0,0, a);
    g.dispose() ;
  }
}

/* --------------------  定义导弹发射架类 -------------------------- */

class Launcher extends Piece {
  public Launcher (Launch_Missiles a) {
    this.a = a ;      // 初始化导弹发射架属性值
    w  = 12 ;
    h  = 22 ;
    px = opx = a.window_size.width/2 ;
    py = opy = w/2+1 ;
    active = true ;
    img = a.missile ;
  }
  public void move() {    // 移动导弹发射架
    opx = px ;
    opy = py ;
    int dx  = a.mouse_x - px ;
    int abs_dx = Math.abs(dx) ;
    int step = 1 ;
    if (abs_dx > 10)
      step = 5 ;
    else if (abs_dx > 1)
      step = abs_dx/2 ;
    if (dx != 0) {
      px += step*(dx/abs_dx) ;
      if (px < w/2)
        px = w/2 ;
    else if (px > (a.window_size.width - w/2))
      px = a.window_size.width - w/2 ;
    }
  }
  public boolean has_moved() {    // 判断导弹发射架是否移动
    if ((px - opx) != 0)
      return true ;
    return false ;
  }
  public void draw() {    // 绘制导弹发射架
    set_draw_rectangles(a.paint_area, a.new_area) ;
    Graphics bg = a.buffer.getGraphics() ;
    bg.clipRect(a.paint_area.x, a.paint_area.y, w, h);
    bg.drawImage(a.backdrop,0,0,a) ;
    bg.dispose() ;
    if (a.M.active()) {      // 根据导弹的active属性值进行相应的绘制
      a.buf_g.setColor(c);        // 导弹飞行时，发射架外观为一实心矩形
      a.buf_g.fillRect(a.new_area.x, a.new_area.y, w, h);
    }
    else {        // 否则，发射架外观为一竖立的导弹
      bg = a.buffer.getGraphics() ;
      bg.clipRect(a.new_area.x, a.new_area.y, w, h);
      bg.drawImage(img,a.new_area.x,a.new_area.y,a) ;
      bg.dispose() ;
    }
    a.paint_area.add(a.new_area) ;      // 使用新的区域
    Graphics g = a.getGraphics() ;      // 将缓冲绘制到屏幕上
    g.clipRect(a.paint_area.x ,a.paint_area.y, a.paint_area.width, a.paint_area.height);
    g.drawImage(a.buffer, 0, 0, a);
    g.dispose() ;
  }
}

/* --------------------  定义导弹Missile类 -------------------------- */

class Missile extends Piece {
  public Missile (Launch_Missiles a) {
    this.a = a ;      // 初始化导弹属性值
    px = opx = 0 ;
    py = opy = 0 ;
    vx = 0 ;
    vy = 7 ;
    w  = 12 ;
    h  = 22 ;
    active = false ;
    img = a.missile ;
  }
  public void move() {    // 移动对象
    opx = px ;
    opy = py ;
    px = a.L.px ;
    int dx = px - opx ;
    int nvy = vy*vy - dx*dx ;
    if (nvy > 0) nvy = (int) Math.sqrt(nvy) ;
    if (nvy < 1) nvy = 1 ;
    py += nvy ;
    if (py > a.window_size.height + 2*h) active = false ;
  }
  int seq  = 0 ;
  public void draw() {    // 绘制导弹
    set_draw_rectangles(a.paint_area, a.new_area) ;      // 设置绘制区域
    Graphics bg = a.buffer.getGraphics() ;
    bg.clipRect(a.paint_area.x, a.paint_area.y, w, h);
    bg.drawImage(a.backdrop,0,0,a) ;
    bg.dispose() ;
    seq = ++seq % 1 ;
    int dx = px - opx ;
    seq = 0 ;
    if (dx > 0)
      seq = 1 ;
    else if (dx < 0)
      seq = 2 ;
    bg = a.buffer.getGraphics() ;
    bg.clipRect(a.new_area.x, a.new_area.y, w, h);
    bg.drawImage(img,a.new_area.x-w*seq,a.new_area.y,a) ;
    bg.dispose() ;
    a.paint_area.add(a.new_area) ;
    Graphics g = a.getGraphics() ;
    g.clipRect(a.paint_area.x ,a.paint_area.y, a.paint_area.width, a.paint_area.height);
    g.drawImage(a.buffer, 0, 0, a);
    g.dispose() ;
  }
}

/* --------------------  定义飞行物Flyer类 -------------------------- */

class Flyer extends Piece {
  public Flyer (Launch_Missiles a) {
    this.a = a ;      // 初始化飞行物属性值
    vx = (Math.random() > 0.5 ? 1 : -1) ;
    vy = -2 ;
    w  = 20 ;
    h  = 8 ;
    int aw = a.window_size.width ;
    px = opx =  (int) (w/2+1 + (aw-w-2)* Math.random()) ;
    py = opy = a.window_size.height + h/2 + 1  ;
    active = true ;
    img = a.ufostrip ;
  }
  public void move() {    // 移动飞行物
    opx = px ;
    opy = py ;
    px += vx ;
    py += vy ;
    if (py < -h/2) active = false ;
    if ((px <= w/2) || (px >= (a.window_size.width - w/2)) ||
        (Math.random() > 0.96)) {
      vx = -vx ;
    }
  }
  int seq  = 0 ;
  int seq2 = 0 ;
  public void draw() {    // 绘制飞行物
    set_draw_rectangles(a.paint_area, a.new_area) ;
    Graphics bg = a.buffer.getGraphics() ;
    bg.clipRect(a.paint_area.x, a.paint_area.y, w, h);
    bg.drawImage(a.backdrop,0,0,a) ;
    bg.dispose() ;
    if ((++seq2 % 4) == 0) seq = ++seq % 4 ;
    bg = a.buffer.getGraphics() ;
    bg.clipRect(a.new_area.x, a.new_area.y, w, h);
    bg.drawImage(img,a.new_area.x-w*seq,a.new_area.y,a) ;
    bg.dispose() ;
    a.paint_area.add(a.new_area) ;
    Graphics g = a.getGraphics() ;
    g.clipRect(a.paint_area.x ,a.paint_area.y, a.paint_area.width, a.paint_area.height);
    g.drawImage(a.buffer, 0, 0, a);
    g.dispose() ;
  }
}

/* --------------------  定义爆炸Explosion类 -------------------------- */

class Explosion extends Piece {
  public Explosion (Launch_Missiles a, int x, int y) {
    this.a = a ;      // 初始化爆炸对象属性值
    w  = 30 ;
    h  = 30 ;
    px = opx = x ;
    py = opy = y ;
    active = true ;
    img = a.missile_explosion ;
  }
  int seq  = 0 ;
  int seq2 = 0 ;
  public void draw() {
    set_draw_rectangles(a.paint_area, a.new_area) ;
    Graphics bkd_g = a.backdrop.getGraphics();
    bkd_g.clipRect(a.paint_area.x, a.paint_area.y, w, h);
    bkd_g.drawImage(a.bgimg,0,0,a.window_size.width,a.window_size.height,a) ;
    if ((++seq2 % 4) == 0) seq = ++seq % 5 ;
    if (seq == 4) active = false ;
    bkd_g.clipRect(a.new_area.x, a.new_area.y, w, h);
    bkd_g.drawImage(img,a.new_area.x-w*seq,a.new_area.y,a) ;
    bkd_g.dispose() ;
    Graphics bg = a.buffer.getGraphics() ;
    bg.clipRect(a.new_area.x,a.new_area.y,w,h);
    bg.drawImage(a.backdrop,0,0,a) ;
    bg.dispose() ;
    Graphics g = a.getGraphics() ;
    g.clipRect(a.paint_area.x ,a.paint_area.y, a.paint_area.width, a.paint_area.height);
    g.drawImage(a.buffer, 0, 0, a);
    g.dispose() ;
  }
  public void erase() {    // 清除爆炸
    set_draw_rectangles(a.paint_area, a.new_area) ;
    Graphics bkd_g = a.backdrop.getGraphics();
    bkd_g.clipRect(a.paint_area.x, a.paint_area.y, w, h);
    bkd_g.drawImage(a.bgimg,0,0,a.window_size.width,a.window_size.height,a) ;
    bkd_g.dispose() ;
    super.erase() ;
  }
}