The Building Coder

Launching AutoCAD within a Revit Add-in

We looked at the topic of running AutoCAD inside a Revit add-in way back in 2008, in the grey and dusty beginnings of this blog.

Many developers have made use of that since then, and the topic is still important for all those who have significant functionality running inside an AutoCAD application and wish to make use of or enhance it by connecting it with their Revit add-in.

Therefore, it is about time to dig that out and have a fresh look at it. Actually, it is rather overdue. I have some more up-to-date information on this that has been sitting around on my to-do list for quite a while. In fact, it is high time to get it out there before it becomes obsolete, and should still prove useful to anyone interested in this topic.

Actually, here are two separate solutions, testole.zip and Acctrl_Interops.zip + EmbedAutoCAD.zip.

Testole.zip

I will simply provide the sample code as it is with no further comment:

// This could have been read-only, but then it 
// cannot be started in zero document state:
 
[Transaction( TransactionMode.Manual )]
public class Command : IExternalCommand
{
  public Result Execute(
    ExternalCommandData commandData,
    ref string message,
    ElementSet elements )
  {
    Autodesk.AutoCAD.Interop.AcadApplication a
      = new Autodesk.AutoCAD.Interop.AcadApplication();
 
    a.Visible = true;
 
    Autodesk.AutoCAD.Interop.AcadDocument doc
      = a.Documents.Application.ActiveDocument;
 
    double[] stpoint = new double[3];
    double[] enpoint = new double[3];
    stpoint[0] = 5;
    stpoint[1] = 5;
    stpoint[2] = 0;
    enpoint[0] = 12;
    enpoint[1] = 3;
    enpoint[2] = 0;
 
    doc.ModelSpace.AddLine( stpoint, enpoint );
 
    doc.SaveAs( "C:/tmp/testline.dwg" );
 
    a.Quit();
 
    return Result.Succeeded;
  }
}

That shows how simple this can be.

Here is testole.zip containing the complete Visual Studio solution.

This is up to you to explore further on your own, if you like :-)

2. Acctrl_Interops.zip + EmbedAutoCAD_2012.zip

The second solution is not directly related to the Revit API, but should work in an add-in as well. It was prompted by the following query:

Question: How can I view and manipulate DWG files in a Windows form?

I want to create an AutoCAD add-in that shows a preview of another DWG file (not the current one) in a VB.NET form and then switch some layers on and off.

I am using Visual Studio 2010.

Answer: You can use the AutoCAD control AcCtrl for this.

Kean's article on embedding AutoCAD in a standalone dialog explains everything in full detail.

Response: This control does not seem to work with VS 2010 on the .NET framework 4.

Answer: I have attached the sample project that uses the Acctrl.dll from AutoCAD 2012 and Visual Studio 2010 with the .NET 4 framework.

The code is identical to the one that you download from the blog and works fine.

Here are the only things I changed:

• I used aximp to generate the interop DLLs from Acctrl.dll and attached them below in Acctrl_Interops.zip. These interop DLLs need to be referenced in the project.
• Set the 'Embed Interop types' toggle to False in the properties of these references.

Here are the two attachments, Acctrl_Interops.zip containing the interop DLLs I generated and EmbedAutoCAD.zip containing the complete Visual Studio solution using them.

I hope you find this useful!

AutoCAD 2010 DWG Export

Today is a public holiday in Neuchâtel, the jeûne fédéral or Federal Fast holiday. I will use that for a hike in the Swiss mountains, that I so sorely neglected and missed this summer.

Meanwhile, here is a simple question on the AutoCAD file format version used for DWG export.

Question: How can I set the AutoCAD 2010 version as the destination file format for DWG export?

The ACADVersion enumeration only has options for 2000, 2004, and 2007.

In the user interface, it is possible to select 2010 as well.

Answer: Looking at the ACADVersion enumeration, I see the following entries:

• Default: The Autodesk Revit application's default export format.
• R2000: AutoCAD 2000 file format.
• R2004: AutoCAD 2004 file format.
• R2007: AutoCAD 2007 file format.

The AutoCAD 2010 file format was recently added as another format in the DWG export options. It is currently created by specifying the 'Default' value.

Because this is a simple enum wrapper, you can also cause Revit to export the AutoCAD 2010 file format by passing in '4' to the options settings. Using Reflector, you can see that the numerical values of the existing entries are 0-3, which makes it very probable that 4 is the next one. In any case it worked, for example, using the following code:

  DWGExportOptions options = new DWGExportOptions();
 
  options.FileVersion = ( ACADVersion ) ( 4 );
 
  ViewSet views = new ViewSet();
 
  views.Insert( uiDoc.Document.ActiveView );
 
  uiDoc.Document.Export( @"d:\temp", @"junk.dwg", 
    views, options );

This creates a resulting DWG file in AutoCAD 2010 file format with a header of ac1024, equal to the ObjectARX enum value kDHL_1024 = 29, which stands for '2010 final'.

As said, ACADVersion.Default also results in an AutoCAD 2010 file format DWG, but that will obviously change in future releases.

Casting an integer to an enum value to pass into the settings is obviously not an officially supported way of using the Revit API, but it might help you get around this in the short term.

DevCamp, Devlabs and Updated API Training Schedule

DevCamp

Registration for the AEC DevCamp on June 7-9, 2010, in Boston, MA has opened. This is the software developer conference for anyone considering or actively developing applications and integrations with Autodesk architecture, engineering, and construction technologies. Besides all versions of Revit, this also includes AutoCAD Architecture, Navisworks, and the infrastructure technologies Civil 3D, Map 3D and MapGuide Enterprise.

During the three days, we will be holding more than twenty training classes on the various APIs, including introductory classes for people just starting to customise and advanced topics for professional developers. There is also a business track for software business owners. Here are some of the beginner classes, most of which are targeted at Revit:

• Introduction to .NET programming for non-programmers
• What's new in Revit 2011 and how to use it
• Introduction to the Revit API – Part 1 and 2
• Leverage your content creation using the Revit API
• Revit Structure API: analytical model and rebar
• Introduction to Navisworks .NET API
• AutoCAD MEP API programming
• Introduction to the AutoCAD Civil 3D .NET API
• An introduction to AutoCAD .NET API programming
• An introduction to AutoCAD Architecture .NET API programming

These are some of the expert classes:

• Presenting your analysis data in Revit
• Creating and analyzing conceptual massing geometry with the Revit API
• Analyze geometry of buildings using the Autodesk Revit API
• Tips and tricks exploiting the Revit 2011 API
• Dynamic interactions with the Revit model
• The Revit MEP API
• AutoCAD MEP content creation – best practices from an expert
• AutoCAD Civil 3D alignments and profiles automation in .NET
• AutoCAD Civil 3D styles and command settings automation in .NET
• Surface manipulation through the AutoCAD Civil 3D COM API from a .NET application
• Migrating AutoCAD Civil 3D subassemblies from VBA to .NET and introduction to pipe rules
• The AutoCAD Map 3D workflow API
• MapGuide Enterprise application development using FUSION Technology
• VBA to .NET migration

There is also a track of classes on sharing, including

• The Doctor is in – bring your personal development challenges, problems and needs to get expert advice and help
• AutoCAD Civil 3D .NET usability study with your input!
• Talk to the Revit Product Managers
• Talk to the Civil 3D Product Managers

And finally, a dedicated business track covers topics such as teaming with the Autodesk sales team and resellers, leveraging your relationship with Autodesk, and understanding Autodesk mergers and acquisitions.

I am very excited about this event, partly since I will be giving some of the presentations myself, and partly because several of the expert classes will be presented by members of the Revit development team and are guaranteed to contain in-depth information that is new to me and not obtainable elsewhere.

Here is the full agenda, and further information and registration access is available from the DevCamp 2010 website. An early bird discount rate applies until April 30, 2010.

API Training Schedule

It is still a while before that becomes imminent, though. Meanwhile, I am still working full tilt on preparing the upcoming Revit API training for Warsaw. It will be based on the new version of the API, so there is a lot of stuff to update to get all the samples working and the documentation adapted. We updated the API training schedule (which you can also access from the easy-to-remember URL autodesk.com/apitraining). It includes both class room and webcast trainings on the Revit API. To see them all, simply select 'Revit API' from the 'Course' pulldown. Due to increasing popular demand and also because quite a lot has changed in the Revit 2011 API, we have more class room trainings scheduled this year:

• April 7 – Warsaw
• May 4 – Farnborough
• Jul 22 – Beijing
• Jul 27 – Munich
• Aug 12 – Chennai

DevLabs

The DevCamp is directly followed by one of the DevLabs that we are holding and which are both free and open to all developers, completely independently of ADN membership, and also listed in the training schedule. Please note that the Waltham one directly after DevCamp was not present in the original list published by Kean. Our current schedule includes the following DevLabs with support for Revit development:

• June 10-11 – Waltham, USA – register
• June 21-25 – Munich, Germany
• August 9-10 – Beijing, China

Please also note that when I last looked, these three all had different course descriptions in the training schedule. To find all three of them, you had to search for the following three separate descriptions:

• DevLab (AEC)
• DevLab (AutoCAD, Inventor & Revit)
• DevLab (Revit and Inventor)

So, lots of events, lots to prepare, lots of exciting meetings to look forward to!

I hope to see you at one of these venues!

Roof Eave Cut in AutoCAD Architecture and Revit

Here is a case that is interesting in its own right, or rather two separate cases and a comparison between the two. The issue is the programmatic setting of the roof eave cut property in AutoCAD Architecture and Revit, respectively. One interesting aspect is the similarity and differences between the two solutions.

First of all, here is the original question, addressed at ACA:

Question: I am having difficulty accessing the edges of a RoofSlab entity. I am programming in C#. I need to change the EdgeCut to a Plumb Cut and I don't know how to access the edges so that I can change the property from Square Cut to Plumb Cut.

Setting the SlabEdge.IsPlumbCut Property in AutoCAD Architecture

In ACA, this issue can also be formulated like this:

Question: How can I define the roof slab edge plumb cut property and set it to plumb or square cut in AutoCAD Architecture? The ACA.NET API SlabEdge.IsPlumbCut property is read-only, so some other method is needed.

Answer: As said, the required property is represented by the SlabEdge.IsPlumbCut property, which is read-only in the API. So you are searching for write access to this property?

This property can be controlled by the roof slab style. One way to change it is to set up an appropriate edge style. You can define an edge style that uses the plumb orientation by default and then define a slab style using that edge style. When you convert to slab, use that slab style, and the plumb edge will come with it.

You can also directly access and write to this property on each edge individually, independently of the edge style, by using the SlabEdge.SetCutOption method. The setting of this property is displayed when you select the 'Edges' entry in the roof slab property palette:

I implemented a sample ACA.NET application PlumbCut which toggles the state of this setting on each edge of a selected roof slab every time it is called. Here is the relevant code snippet from the command method implementation:

  RoofSlab roofSlab = t.GetObject( 
    entId, OpenMode.ForWrite ) as RoofSlab;
 
  SlabFace face = roofSlab.Face;
 
  foreach( SlabLoop loop in face.Loops )
  {
    foreach( SlabEdge edge in loop.Edges )
    {
      bool isPlumb = edge.IsPlumbCut;
 
      // SlabEdge.IsPlumbCut cannot be assigned 
      // to -- it is read only:
      //edge.IsPlumbCut = !edge.IsPlumbCut; 
 
      edge.SetCutOption( isPlumb );
    }
  }

Here is the complete PlumbCut ACA.NET command source code and the complete Visual Studio solution to build it.

So much for AutoCAD Architecture. Here is an answer to the analogue question in the context of Revit:

Setting the Roof Eave Cut Property in Revit

Question: How can I define the roof eave cut property and set it to plumb or square cut in Revit?

Answer: I created a very simple sample model consisting of four walls supporting a footprint roof to explore your query and see the property you are looking for, the roof element Rafter Cut property, which can take the following values:

• Plumb Cut
• Two Cut - Plumb
• Two Cut - Square

These values correspond to the following EaveCutterType enumeration values in the API:

• PlumbCut
• TwoCutPlumb
• TwoCutSquare

Exploring the roof element parameters using RvtMgdDbg, I can see that these values are stored in the integer-valued built-in parameter ROOF_EAVE_CUT_PARAM.

To ensure that this parameter can be accessed and its integer value read and written using the EaveCutterType enumeration values, I implemented an external command and a sample application RoofEaveCut. To run it, you need to pre-select a foot print roof in the model. Then, each time you call the external command, the value of the Rafter Cut property is cycled through the three values listed above. This demonstrates that you can both read and write the built-in ROOF_EAVE_CUT_PARAM parameter value as an integer and cast it to the EaveCutterType enumeration values. Here is the relevant code snippet:

const string _prompt 
  = "Please select a single foot print roof element.";
 
const BuiltInParameter _bip 
  = BuiltInParameter.ROOF_EAVE_CUT_PARAM;
 
public IExternalCommand.Result Execute( 
  ExternalCommandData commandData, 
  ref string message, 
  ElementSet elements )
{
  Application app = commandData.Application;
  Document doc = app.ActiveDocument;
  ElementSet els = doc.Selection.Elements;

  if( 1 != els.Size )
  {
    message = _prompt;
  }
  else
  {
    FootPrintRoof roof = null;
    foreach( Element e in els )
    {
      roof = e as FootPrintRoof;
    }
    if( null == roof )
    {
      message = _prompt;
    }
    else
    {
      Parameter p = roof.get_Parameter( _bip );
      int i = p.AsInteger();
      switch( i )
      {
        case (int) EaveCutterType.PlumbCut: 
          i =(int) EaveCutterType.TwoCutPlumb; 
          break;
 
        case (int) EaveCutterType.TwoCutPlumb: 
          i =(int) EaveCutterType.TwoCutSquare; 
          break;
 
        case (int) EaveCutterType.TwoCutSquare: 
          i =(int) EaveCutterType.PlumbCut; 
          break;
      }
      p.Set( i );
    }
  }
  return 0 == message.Length
    ? IExternalCommand.Result.Succeeded
    : IExternalCommand.Result.Failed;
}

Here is the complete RoofEaveCut Revit external command source code and the complete Visual Studio solution to build it.