判断三角形三个点是逆时针还是顺时针

       Vector2 p1 =  Pos[0].position;
        Vector2 p2=  Pos[1].position;
        Vector2 p3 = Pos[2].position;

        if ((p2.x - p1.x) *(p3.y - p1.y) -(p3.x - p1.x) *(p2.y-p1.y) < 0)  
        {  
            Debug.Log("顺时针") ;  
        }  
        else  
        {
            Debug.Log("逆时针") ;  
        }