if (x1 >= m_x &&  y1 >= m_y) {
    //I
    //cout << "I" << endl;

    if (x1 >= x2 && y1 <= y2)
    zRot += dR;
    else
    zRot -= dR;

    }
    else
    if (x1 >= m_x &&  y1 <= m_y) {
    //II
    //cout << "II" << endl;

    if (x1 >= x2 && y1 >= y2)
    zRot -= dR;
    else
    zRot += dR;
    }
    else
    if (x1 <= m_x &&  y1 <= m_y) {
    //III
    //cout << "III" << endl;
    if (x1 <= x2 && y1 >= y2)
    zRot += dR;
    else
    zRot -= dR;
    }
    else
    if (x1 <= m_x &&  y1 >= m_y) {
    //IV
    //cout << "IV" << endl;
    if (x1 >= x2 && y1 >= y2)
    zRot += dR;
    else
    zRot -= dR;
    }

---------------------------------------------------------

    if (x1 >= m_x &&  y1 >= m_y || x1 <= m_x &&  y1 <= m_y)
     {
      if (x1 > x2 && y1 < y2)
      zRot += dR;
      else if (x1 < x2 && y1 > y2)
      zRot += dR;
          else
      zRot -= dR;
     }
    else if (x1 >= m_x &&  y1 <= m_y || x1 <= m_x &&  y1 >= m_y)
     {
        //II
     if (x1 >= x2 && y1 >= y2)
      zRot -= dR;
     else if (x1 >= x2 && y1 >= y2)
     zRot += dR;
         else
     zRot -= dR;
     }