double dl1 = (aLastPnt1.X()-xg)*(aLastPnt1.X()-xg) + (aLastPnt1.Y()-yg)*(aLastPnt1.Y()-yg);
double df2 = (aFirstPnt2.X()-xg)*(aFirstPnt2.X()-xg) + (aFirstPnt2.Y()-yg)*(aFirstPnt2.Y()-yg);
double dl2 = (aLastPnt2.X()-xg)*(aLastPnt2.X()-xg) + (aLastPnt2.Y()-yg)*(aLastPnt2.Y()-yg);
double dl1 = (aLastPnt1.X()-xg)*(aLastPnt1.X()-xg) + (aLastPnt1.Y()-yg)*(aLastPnt1.Y()-yg);
double df2 = (aFirstPnt2.X()-xg)*(aFirstPnt2.X()-xg) + (aFirstPnt2.Y()-yg)*(aFirstPnt2.Y()-yg);
double dl2 = (aLastPnt2.X()-xg)*(aLastPnt2.X()-xg) + (aLastPnt2.Y()-yg)*(aLastPnt2.Y()-yg);