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，事实上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;
    }
    // 改动当前对象的位置
    var newPosition = cc.p(x2, y2);
    this.setPosition(newPosition);
    // 旋转对应的角度
    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