package ifrog.math
{
  import flash.geom.Point;
  
  /**
  * 贝塞尔工具
  * @author Larry H.
  * @createTime 2012/8/21 16:24
  * 
  * 绘制贝赛尔曲线点
  * @param   list    控制点
  * @param   ratio   贝赛尔曲线比例
  * @return  返回ratio比例对应贝赛尔曲线上的点坐标
  * list.length代表贝赛尔曲线的阶数，一般二阶即可满足需要，二阶需要三个点
  */
  public function bezier(list:Array/*list.length >= 2*/, ratio:Number/*0 =< ratio <= 1*/):Point
  {
      if (!list) return null;
      
      if (list.length > 1)
      {
          var pos:Point;
          var length:int = list.length;
          for (var i:int = 0; i < length - 1; i++)
          {
              pos = list[i];
              
              list[i] = new Point();
              list[i].x = (1 - ratio) * pos.x + ratio * list[i + 1].x;
              list[i].y = (1 - ratio) * pos.y + ratio * list[i + 1].y;
          }
          
          list.pop();
          return arguments.callee.apply(null, arguments);
      }
      
      return list[0];
  }
}