revit api创建模型线

public void CreateModelCurve()
{
   Document doc = this.ActiveUIDocument.Document;    
   // 在族文档中找到名字为"Ref. Level"的标高
   FilteredElementCollector collector = new FilteredElementCollector(doc);
   collector = collector.OfCategory(BuiltInCategory.OST_Levels);
   var levelElements = from element in collector where element.Name == "Ref. Level" select element;  
   List<Autodesk.Revit.DB.Element> levels = levelElements.ToList<Autodesk.Revit.DB.Element>();        
   if(levels.Count <= 0)
      return;            
   Level refLevel = levels[0] as Level;
            
   // 创建一条几何直线，一个基于标高的草图平面，然后在这个草图平面上创建一条模型线.
   using(Transaction trans = new Transaction(doc, "Create model line."))
   {
      trans.Start();    
      Line line = Line.CreateBound(XYZ.Zero, new XYZ(10,10,0));
      SketchPlane sketchPlane = SketchPlane.Create(doc, refLevel.Id);        
      ModelCurve modelLine = doc.FamilyCreate.NewModelCurve(line, sketchPlane);
     trans.Commit();
   }
}