/// <summary>
/// 点投影到线
/// </summary>
/// <param name="po"></param>
/// <param name="l"></param>
/// <returns></returns>
public static Point ProjectTo(this Point po, Line l)
{
XYZ dbpo = po.ToXyz();
DBcurve dbline = l.ToRevitType();
XYZ newpo = dbline.Project(dbpo).XYZPoint;
return(Point.ByCoordinates(newpo.X, newpo.Y, newpo.Z));
}