public static void CreateHelix(List<helix> helixes)
        {
            Document doc = Application.DocumentManager.MdiActiveDocument;
            Editor ed = doc.Editor;
            //using (DocumentLock docLock = doc.LockDocument())
            //{
                using (var trans = doc.TransactionManager.StartTransaction())
                {
                    BlockTable blockTable = trans.GetObject(doc.Database.BlockTableId, OpenMode.ForRead) as BlockTable;
                    BlockTableRecord space = trans.GetObject(blockTable[BlockTableRecord.ModelSpace], OpenMode.ForWrite) as BlockTableRecord;
                   foreach (var helix1 in helixes)
                    {
                    Helix acHelix = new Helix();
                    acHelix.SetDatabaseDefaults();
                    acHelix.Constrain = ConstrainType.Turns;//设置这个注意
                    acHelix.StartPoint = Point3d.Origin;
                    acHelix.BaseRadius = helix1.baseRadius;
                    acHelix.TopRadius = helix1.topRadius;
                    acHelix.Height = helix1.height;
                    acHelix.TurnHeight = helix1.turnHeight;
                    acHelix.Turns = helix1.turns;
                    acHelix.Twist = false;
                    acHelix.CreateHelix();
                    space.AppendEntity(acHelix);
                    trans.AddNewlyCreatedDBObject(acHelix, true);

                }

                    trans.Commit();
                }

            //}


        }