cocos2d-js导弹跟踪算法一边追着目标移动一边旋转角度

跟踪导弹 

function(targetPosition){
    // 让物体朝目标移动的方法  var speed = 5;
    var targetPoint = targetPosition;
    var thisPoint = cc.p(this.x,this.y);
    //求两点的差值，其实就是两点的坐标相减  var delta = cc.pSub(targetPoint,thisPoint);
    // 求当前对象和目标两点间的距离  var distance = cc.pdistance(thisPoint,targetPoint);
    // 计算行走后的点xy坐标  var x2 = thisPoint.x +speed *delta.x /distance;
    var y2 = thisPoint.y + speed *delta.y/distance;
    if(100>=distance){
        return true;
    }
    // 修改当前对象的位置  var newPosition = cc.p(x2,y2);
    this.setPosition(newPosition);
    // 旋转相应的角度  var x1 = thisPoint.x;
    var y1 = thisPoint.y;
    var delTarotation = 90-Math.atan2(y2-y1,x2-x1)*180/Math.PI;
    this.setRotation(delTarotation);
    return false;
}效果请看游戏地址 http://www.seraph-fd.cn/games/1/index.html