Autodesk Answer Days – Revit and Create a Roof from the API

By Jaime Rosales (@afrojme)

Autodesk Answer Days – Revit, October 7, 2015

Do you have any Revit® or Revit LT® questions that you’ve always wanted to ask?

If yes, then join the latest installment of Ask Autodesk Anything events on October 7, 2015. This event is dedicated to answering your questions about Revit and Revit LT. We’ll have some DevTech engineers attending the event to answer your API questions. The event runs from 6 am to 6 pm Pacific Time and will take place in Autodesk Community. Come spend a minute, an hour, or the whole day in the Autodesk Community to interact directly with the folks who bring this award-winning building information modeling software!

Click here for more information.

This week I have a chance to help a developer looking for a way on how to create a roof through the API. Interesting question since I don’t think I never tried that before so it was a fun piece to work on. Here is the question from our Forum community.

Question:  I’m having trouble to create a roof via code. I know how to create a stairs for example : I start a StairsEditScope and use CreateSketchedLanding with all the right parameters to create my stairs and just commit the StairsEditScope, but for a roof i cant find a clue on how to create it from scratch, any leads?

And if there isn’t a way, for example: ceiling i know there isn’t a way so i need to use a floor as a ceiling workaround. But for roof I don’t have a workaround.

Answer:Here is a command to create a roof, Just make sure you have some walls to hold it and also one of your levels is named "Roof".

I created a simple 4 walls rectangle and the selected them and ran the command that I’m providing.

You can read more about this sample in the Revit Help file, here is the link.

#region Namespaces
using System;
using System.Collections.Generic;
using System.Diagnostics;
using Autodesk.Revit.ApplicationServices;
using Autodesk.Revit.Attributes;
using Autodesk.Revit.DB;
using Autodesk.Revit.UI;
using Autodesk.Revit.UI.Selection;
using System.Linq;
#endregion

namespace CreateRoof
{
    [Transaction(TransactionMode.Automatic)]
    public class Command : IExternalCommand
    {
        public Result Execute(
          ExternalCommandData commandData,
          ref string message,
          ElementSet elements)
        {
            UIApplication uiapp = commandData.Application;
            UIDocument uidoc = uiapp.ActiveUIDocument;
            Application app = uiapp.Application;
            Document doc = uidoc.Document;

            // Before invoking this sample, select some walls to add a roof over.
      &#16
0;     // Make sure there is a level named "Roof" in the document.

            // find the Roof level
            FilteredElementCollector collector = new FilteredElementCollector(doc);
            collector.OfClass(typeof(Level));
            var elem = from element in collector where element.Name 

            == "Roof" select element;
            Level level = elem.Cast<Level>().ElementAt<Level>(0);

            collector = new FilteredElementCollector(doc);
            collector.OfClass(typeof(RoofType));
            RoofType roofType = collector.FirstElement() as RoofType;

            // Get the handle of the application
            Autodesk.Revit.ApplicationServices.Application application = doc.Application;

            // Define the footprint for the roof based on user selection
            CurveArray footprint = application.Create.NewCurveArray();
            
            ICollection<ElementId> selectedIds = uidoc.Selection.GetElementIds();
            if (selectedIds.Count != 0)
            {
                foreach (ElementId id in selectedIds)
                {
                    Element element = doc.GetElement(id);
                    Wall wall = element as Wall;
                    if (wall !=
 null)
                    {
                        LocationCurve wallCurve = wall.Location as LocationCurve;
                        footprint.Append(wallCurve.Curve);
                        continue;
                    }

                    ModelCurve modelCurve = element as ModelCurve;
                    if (modelCurve != null)
                    {
                        footprint.Append(modelCurve.GeometryCurve);
                    }
                }
            }
            else
            {
                throw new Exception          ("You should select a curve loop,

                                                           or a wall loop, or loops combination

                                                           \nof walls and curves to create a footprint roof.");
            }

            ModelCurveArray footPrintToModelCurveMapping = new ModelCurveArray();
            FootPrintRoof footprintRoof = doc.Create.NewFootPrintRoof

            (footprint, level, roofType,out footPrintToModelCurveMapping);
            ModelCurveArrayIterator iterator = 

            footPrintToModelCurveMapping.ForwardIterator();
            iterator.Reset();
            while (iterator.MoveNext())
            {
                ModelCurve modelCurve = iterator.Current as ModelCurve;
                footprintRoof.set_DefinesSlope(modelCurve, true);
                footprintRoof.set_SlopeAngle(modelCurve, 0.5);
            }

            return Result.Succeeded;
        }
    }
}