convert2DPointTo3DPoint

gp_Pnt ViewCalculations::convert2DPointTo3DPoint(Standard_Real x, Standard_Real y, Handle(V3d_View) aView)
{
    V3d_Coordinate XEye,YEye,ZEye,XAt,YAt,ZAt;
    aView->Eye(XEye,YEye,ZEye);
    aView->At(XAt,YAt,ZAt);
    gp_Pnt EyePoint(XEye,YEye,ZEye);
    gp_Pnt AtPoint(XAt,YAt,ZAt);

    gp_Vec EyeVector(EyePoint,AtPoint);
    gp_Dir EyeDir(EyeVector);

    gp_Pln PlaneOfTheView = gp_Pln(AtPoint,EyeDir);
    Standard_Real X,Y,Z;
    aView->Convert(int(x),int(y),X,Y,Z);
    gp_Pnt ConvertedPoint(X,Y,Z);
    gp_Pnt2d ConvertedPointOnPlane = ProjLib::Project(PlaneOfTheView,ConvertedPoint);

    gp_Pnt ResultPoint = ElSLib::Value(ConvertedPointOnPlane.X(),
                                       ConvertedPointOnPlane.Y(),
                                       PlaneOfTheView);

    return ResultPoint;
}