切水果游戏中的刀的实现

   在开发一个游戏时候，需要用到这样的效果。
   首先定义

    private Paint mPaint_weapon = null; // 真实的画笔   

    private Path mPath_weapon = null; // 

   // private Point fly_middle;

   private ArrayList<PointF> weapon_Track;

  private int weapon_Track_w = 1;  //  这里设置刀的宽度哦，想刀宽一点就把这个值调大一点，不要太大哦

  private int weapon_color_r = 0xff, weapon_color_g = 0x00, weapon_color_b = 0x00;  // 橙色#FF0000   紫色 800080  蓝色00BFFF    淡绿色7CFC00    淡 FFFF00  白色 FFFAFA   红色480000    配置不同的颜色就是不同的刀哦

首先在：
 public boolean onTouchEvent(MotionEvent event) {
.....// 此处省略一些字符
case MotionEvent.ACTION_DOWN: 

         if(mPath_weapon != null)mPath_weapon.reset();

           if(weapon_Track != null)weapon_Track.clear();

.....// 此处省略一些字符
case MotionEvent.ACTION_MOVE:  

            synchronized(weapon_Track){

           if(weapon_Track.size() > 7){

           weapon_Track.remove(0);

           }

           

            weapon_Track.add(new PointF(event.getX(), event.getY()));

            } 
.....// 此处省略一些字符

最后是核心代码：

    private void Draw_warrior_weaponHitOut(Canvas canvas) {

    if(DEBUG)Log.v("yuyongjun", "Draw_warrior_weaponHitOut)");

    synchronized(weapon_Track)

    {

if(weapon_Track.size()>1){

endX =  weapon_Track.get(0).x;

endY =  weapon_Track.get(0).y;

weapon_Track_w = 1;

mPaint_weapon.setARGB(0xff, weapon_color_r, weapon_color_g, weapon_color_b);  

for(int i=0;i<weapon_Track.size()-1;i++){  //先绘制刀 

startX = endX;

startY = endY;

controlX = weapon_Track.get(i).x;

controlY = weapon_Track.get(i).y;

endX = (controlX + weapon_Track.get(i+1).x)/2;

endY = (controlY + weapon_Track.get(i+1).y)/2;

mPath_weapon.moveTo(startX, startY);

mPath_weapon.quadTo(controlX, controlY, endX, endY);

//mPaint_weapon.setColor(mBladeColor);

mPaint_weapon.setStrokeWidth(weapon_Track_w++);// ﾻﾭﾱￊ﾿￭ﾶ￈   

canvas.drawPath(mPath_weapon, mPaint_weapon);

mPath_weapon.reset();

} 
 startX = endX;

startY = endY;

endX = weapon_Track.get(weapon_Track.size()-1).x;

endY = weapon_Track.get(weapon_Track.size()-1).y;

mPath_weapon.moveTo(startX, startY);

mPath_weapon.lineTo(endX, endY);

mPaint_weapon.setStrokeWidth(weapon_Track_w++);

canvas.drawPath(mPath_weapon, mPaint_weapon);

if(weapon_Track.size() > 3)

{   //这里 去绘制刀的光泽，这里用白色去表示刀的光泽

endX =  weapon_Track.get(3).x;

endY =  weapon_Track.get(3).y;

mPaint_weapon.setARGB(0xc0, 0xff, 0xff, 0xff); 

for(int i=2;i < weapon_Track.size()-1;i++){

startX = endX;

startY = endY;

controlX = weapon_Track.get(i).x;

controlY = weapon_Track.get(i).y;

endX = (controlX + weapon_Track.get(i+1).x)/2;

endY = (controlY + weapon_Track.get(i+1).y)/2;

mPath_weapon.moveTo(startX, startY);

mPath_weapon.quadTo(controlX, controlY, endX, endY);

//mPaint_weapon.setColor(mBladeColor);

mPaint_weapon.setStrokeWidth(i-1);// ﾻﾭﾱￊ﾿￭ﾶ￈   

canvas.drawPath(mPath_weapon, mPaint_weapon);

mPath_weapon.reset();

}

}

// weapon_Track.remove(0);

}

    }

 } 

至于如何判断击中一个目标 ，就很明显了，这里就不告诉大家了。

如果需要看看这样做出来的效果，可以去下载这个小游戏（苍蝇入侵）：http://www.nduoa.com/apk/detail/645882