The Building Coder

Retrieving Detailed Wall Layer Geometry

We start off this week with a bang. I find the following topic especially exciting, for several reasons: It deals with geometry. I like that. It implements something that cannot be achieved out of the box. I like that. It makes use of the Revit 2012 parts functionality and the PartUtils class, which we never looked at in detail before. I like that. It uses a temporary transaction to make changes to the model to create and extract information that... Read more →

Activate a 3D View

Here is a simple question on making use of the ActiveView setter, which is new in Revit 2012: Question: I heard that Revit 2012 exposes an API to change the active view. I would like to change the active view to 3D with the Detail Level set to Fine and Visual Style set to Realistic. Could you please show me the correct way to change the active view to the one I want? Answer: I already discussed setting the visual... Read more →

Wall Joins and Geometry

Once again, here is an issue that shows how Revit keeps strict control over the BIM, and that the possibilities to override the built-in behaviour are intentionally limited: Question: I have found the API method to AutoJoin elements, but I cannot seem to find any method that allows me to simply join two walls, as is possible in the Revit user interface. How can I achieve that? Answer: Basically, as far as I understand Revit, it wants to take and... Read more →

Refresh Element Graphics Display

Here is a little issue with an interesting workaround that I encountered in the past in similar incarnations in other CAD software packages besides Revit, so it is worthwhile making a note of this for potential future use almost anywhere. The issue has to do with refreshing the graphics display of individual elements in the Revit user interface. Committing the transaction, explicit regeneration, and even calling RefreshActiveView does not help. One additional thing that sometimes does help in similar situations... Read more →

MEP Placeholders

Happy Independence Day to all US-Americans, and a wonderful Monday and beginning of the new week to all the rest of us! I recently discussed the Revit MEP 2012 API news and mentioned that MEP placeholders are one of the important new features in both the product and the API. Mostly, new API features are demonstrated by some of the samples provided by the Revit SDK, but the placeholder elements form an exception to that rule. Still, we did present... Read more →

Reloading a Family

Here is an impressively complete list of pretty fundamental beginner's issues that you might potentially run into when reloading a family, starting from scratch, from a recent case handled by my colleague Joe Ye. One of the interesting points that Joe ends up making is that in order to reload a family that has already been loaded into the document, you can use the LoadFamily overload taking an IFamilyLoadOptions argument. Before and after getting to that stage, here are some... Read more →

Loading Only Selected Family Types

As you probably know, the Revit API provides two methods to load family types, also known as symbols: LoadFamilySymbol, which loads an individual type, and LoadFamily, which loads the entire family and all the types it defines. Use of the latter method can be quite time consuming and wasteful, especially if you only require a few of the types included. In the past we also discussed a couple of other issues on handling family types, such as creating a new... Read more →

Visual Studio Add-In Wizards for Revit 2012

As I mentioned yesterday, this weekend was spent traveling to Verona to give a Revit API training here. Happily, I enjoyed some mountain air the weekend before, on Helgenhorn 2837m, Basodino 3273m and Cima di Lago south of All'Acqua in the Bedretto Valley (more photos by Jogi): Anyway, that was last weekend; back to here and now in Verona, where I was busy yesterday, preparing for the training, starting today. I already updated the DevTV Visual Studio wizards for creating... Read more →

Access to Sketch and Sketch Plane

I just presented my first Revit API class here at AU 2010, CP228-2, on the optimal use of the Revit 2011 programming features and the Idling event. I already posted my AU class descriptions and materials. The presentation went well and was good fun. The next one, CP234-2, on Revit 2011 programming optimization and filtered element collectors, is scheduled in an hour's time. Right now I am sitting in on Matt Mason's presentation on Revit parameters. Meanwhile, here is another... Read more →

Pattern for Semi-Asynchronous Idling API Access

Here is another wonderful contribution from Daren Thomas: A Pattern for Asynchronously Updating Revit Documents. As an attentive reader of this blog, you will certainly remember one of my favourite and most powerful recent projects, the modeless loose connector navigator. It retrieves and displays a list of unconnected MEP connectors in a modeless dialogue box. Being modeless, the dialogue is not within the context of a Revit external command Execute method, nor any other Revit API call-back, and thus has... Read more →

Launching a Revit Command

One question that I frequently hear is how to launch a built-in Revit command programmatically. We recently discussed a specific case related to this issue in some depth, how to close the active document and especially pointed out why this is risky, undesirable and not supported. To close the active document, we used the SendKeys.SendWait method provided in the .NET framework System.Windows.Forms namespace. Many of the other attempts that I have seen in the past to launch a Revit command... Read more →

Access Deleted Element

Here is a question posted by Kristian (Krispy5) Parsons, Systems Analyst - Design at Westfield Design & Construction Pty. Ltd. on accessing deleted element data in the DocumentChanged event handler: Question: How do I find the category of the deleted elements? When I try to get the Element from the ElementId it fails since the element has already been deleted. In my case I would like to warn users when they have deleted a floor. Answer: I was planning to... Read more →

Filtered Element Collectors

One of the most important enhancements made in the Revit 2011 API which is guaranteed to affect almost every single conceivable Revit add-in is the new filtered element collector mechanism, and we have already looked at numerous aspects and examples of using it in various ways. It represents the one and only way to access elements in the Revit database, if you disregard a number of dedicated Document properties providing direct access to specialised collections of various types, which can... Read more →

DoorSwing Fix

I am spending this week in the UK. We are having a long-awaited EMEA DevTech team meeting today. We finally succeeded in creating a possibility for all ADN engineers working in the European region to get together face to face. I met some of my colleagues for the first time, for instance Marat, who is based in Moscow, and Kristine from Toronto (not really part of Europe). The rest of the week I will be attending an internal training course,... Read more →

Access to Curtain Grid Panels

Here is some strange behaviour noted by Daren Thomas of the Professur für Gebäudetechnik, Institut für Hochbautechnik at the technical university ETH Zürich and author of the Revit Python shell which led to the discovery and quick fix of a problem in the curtain grid API. Since Daren also provides a workaround for the problem for immediate use, I think it worthwhile to note it here. Question: I just came by some strange behaviour in Autodesk Revit Architecture 2011: It... Read more →

Speed Up Selection

I am now back in Switzerland again after all my various travels, and looking forward to diving into the Revit API in depth again... Here is a really surprising result on how to speed up programmatic selection of a large number of elements, triggered by a question from Joe Offord of Enclos Corp: Question: I have a situation where I'd like to select a large number of curtain panels (over 1000) and add them to my UIDocument.Selection set. These curtain... Read more →

Transaction Migration Errors

Joo Lee just submitted a comment pointing out an error or two in the flat migration of the CmdWallFooting command, which demonstrates an approach to retrieve the host reference using a wall footing: Question: I tested your CmdWallFooting command in Revit Architecture 2011. But it does not work. The transaction is not started. How can I get the transaction to work? Answer: Thank you very much for pointing this out! This command was flat migrated from Revit 2010 and never... Read more →

Modeless Loose Connectors

One of the most enthusiastically received samples I presented at the AEC DevCamp conference has also proved a valuable resource since then, in answering various questions on modeless dialogues and ensuring that the Revit application main window becomes the foreground window in certain situations. It demonstrates how we can combine several ubiquitously useful pieces of functionality that we already discussed in the past to implement a homogenous whole. We create an application which collects information from the Revit model and... Read more →

Place Family Instance

The Revit SDK does not include any example of calling the new PromptForFamilyInstancePlacement method, which prompts the user to interactively and graphically place instances of a specified family symbol, so I am creating a new Building Coder sample command to demonstrate its use. At the same time, I can answer an interesting follow-on question: Question: I am starting to use PromptForFamilyInstancePlacement to get the user to place one or more instances of a family symbol. This method returns void. It... Read more →

DevLab and Birthday

It is Saikat's birthday today, and he is far away from home and family. We prepared a small celebration with flags and cake and a birthday song for him last night: Here is the part of the ADN DevTech AEC workgroup that is present to support the DevLab here in Waltham. From the left: Augusto, Partha, Saikat, Michael (Navisworks team), Mikako, Adam, Jeremy: Happy birthday Saikat! Meanwhile, we are back at DevLab again with a host of exciting developers and... Read more →

To Regenerate or Not to Regenerate...

... that is the question. We already discussed some best practices concerning the regeneration option. A related topic is how often and when to make calls to the Document.Regenerate method, and how to eliminate such calls when possible. One of the issues we ran into during today's DevLab had to do with performance and elimination of extraneous calls to this method. We also learned that the location curve of a newly inserted family instance does not reflect the true insertion... Read more →

AutoJoinElements

I just heard that there is an issue with the Document.AutoJoinElements method. This gave rise to a discussion which raises some interesting points and is worth sharing. For those of you not familiar with this method, here is the brief description from the Revit API help file: AutoJoinElements forces the elements in the Revit document to automatically join to their neighbours where appropriate. Use this method to force elements in the document to automatically join to their neighbours. Note that... Read more →

Asynchronous API Calls and Idling

I discussed the Idling event yesterday, and since received a note from the venerable Revit API guru Guy Robinson who finds this new event just as momentous and exciting as I do and therefore promoted it to the Revit 2011 API standout feature. If Guy likes it, it's the real thing, for sure. Since this once again dives full into the topic of controlling Revit from an external application or a modeless dialogue, here is a very apt comprehensive summary... Read more →

Regeneration Option Best Practices

Our discussion of the risks of using the manual regeneration option triggered several very interesting comments and suggestions. Here are some important fundamental things to note about the regeneration modes: The automatic mode is not new. It is the mode that Revit has been using all along so far. Developers complained that it is too slow, so we introduced the SuspendUpdating mechanism and now the manual option, providing more and more optimisation possibilities. There is no need to overcomplicate things.... Read more →

Object Relationships in VB

We recently presented Saikat Bhattacharya's neat little object relationship analyser and displayer, implemented in C#. Yesterday I received a very friendly submission from Jose Guia saying "Thought I would share my code as well, ... I converted the project to VB for sharing." I compiled his solution and it works fine for me. I did run into two little issues which were easy to solve, both of them involving namespaces: Different access to imported namespaces. Different namespace when exporting the... Read more →

Object Relationships

We already discussed several uses of the Document.Delete method to discover object relationships, e.g. the relationship between a tag and the tagged element, a wall and its footing, host and its hosted elements, the title block of a sheet, or host elements and their openings for the purposes of gross material quantity determination. Another use of it is to obtain the unmodified element geometry. Here is a very neat little sample named ObjRel by Saikat Bhattacharya that shows how to... Read more →

Extra Transaction Required

Here is another interesting issue to discuss in between the series of instalments of background information on the Revit API geometry library from Scott's Autodesk University presentation on analysing building geometry. As we mentioned repeatedly in the past, Revit automatically opens a transaction when an external command is invoked, and closes or aborts it when the command terminates, depending on the command result returned by the Execute method. This affects the document IsModified property and clarifies why you need to... Read more →

Modeless Dialogues in Revit

Here is an overview and summary of a number of discussions that we have already presented previously on driving Revit from outside and interacting with modeless dialogues, which hopefully will help to further clarify the issues involved. Question: How can I use a modeless dialogue in Revit? I need to display a modeless dialogue in Revit. On clicking a button in it, an element should be added to the Revit model. The button can be clicked multiple times and elements... Read more →

External Command Replay

Matt Mason of Avatech Solutions pointed out a few important items related to the preceding post on replaying a journal file: One topic that you did not cover – using the journal file with Revit external commands. Here are some things that I've noticed in the past: If your external command has dialog boxes, your application will freeze if Revit is being driven by a journal. The alternative to this is to use the JournalData StringStringMap in the ExternalCommandData which... Read more →

Journal File Replay

In spite of pretty mixed weather I went on a climb in the alps with my friend Robert on Saturday, the route Kurze Kombination (4c) on the mountain Schmalstöckli (2012 m) close to the Lidernenen Hütte. Here I am after the climb, just below the summit: And this is Robert on the summit itself: We would made another climb on the same mountain if the weather had not been pretty grey and moist. Anyway, now it is Monday morning, and... Read more →

Export Family Instance to gbXML

The Green Building XML Schema or gbXML was developed to facilitate the transfer of building information stored in CAD building information models, enabling interoperability between building design models and a wide variety of engineering analysis tools. It has been widely adopted by leading CAD vendors and is on the road to becoming a de-facto industry standard schema, so we obviously see more and more application developers interested in using and supporting it, leading to questions such as the following one.... Read more →

Host Reference

Still enjoying my climbing and sunshine holiday with my sons in Avignon. Yesterday we went climbing and exploring the cliffs or 'calanque' of Cassis, east of Marseille (more images): Besides climbing, swimming in the Gard river and Mediterranean Sea, and blogging now and then, my sons are also artistically active: Returning to the Revit API, however: We already touched on the relationship between a host and its hosted elements in some previous posts. The first such topic was the relationship... Read more →

Document Modification in an Event

Here is a question raised by Phillip Miller on the topic of the new 2010 events: Question: I'm having trouble with the DocumentClosing event. I want to set parameters of objects as Revit closes down the document. I'm using element.Parameter("Schedule").Set(nul), but the error says that Revit can't do it outside of the transaction. I tried wrapping the command in a Transaction but that fails as well. I am however using the same code to set parameters on objects during the... Read more →

Tag Association

Unfortunately, the Revit API does not currently provide any direct method to access the tag of a tagged element, and vice versa. Normally, I do not write about things that do not work. In this case, however, we have a couple of suggestions for workarounds. I would love to hear back from you whether you are already using any of the methods described below, or other techniques not described, in spite of the lack of direct API support. So this... Read more →

New 2010 Events

The Event API in Revit has been completely rewritten in 2010 to be compliant to the .NET event standard. The old events are still available but have been deprecated. Matt Mason already posted an overview of some of the new event handling features. Transitioning from the old events to the new ones can include some pitfalls, and one has now been uncovered. Question: My application connects to a database when a project is opened. It uses the following code which... Read more →

Transaction Responsibility

The last post on transactions explained the need to open a transaction of our own before trying to modify a document during an event. That is actually not all. We also need to remember that starting a transaction is not permitted at all times, and also that starting a new transaction or ending one may fail. This leaves us with a certain amount of responsibility. Therefore, we should add some error handling to ensure that failures are handled gracefully. The... Read more →

Transactions

We recently mentioned the need to open a transaction in an event handler. In that case, the transaction was required in a handler for the document closed and saved events on the application object. Here is another similar case involving the application OnDocumentNewed event. Question: I am trying to set up some shared parameters on OST_Rooms in a ControlledApplication. I can read and bind values from a shared parameter file, and have checked that the binding is set up correctly... Read more →

Barcelona Questions

Thanks to Alex Vila Ortega of Autodesk Spain, I spent the last couple of days here in Barcelona giving a training class on the Revit API, with lots of professional and enthusiastic participants. Here are some of the questions that we explored. Question: How can I retrieve all the windows hosted by a specific given wall? Answer: Well, one possibility is to make use of the relationship inverter that we already discussed. This will provide a global dictionary mapping each... Read more →

Driving Revit from Outside

We are winding up here at Autodesk University, with a final panel session to meet the AEC API experts yesterday afternoon, and one on advanced use of the Revit API this morning. One topic that keeps cropping up in infinite variations and was mentioned several times in my sessions here at AU is how to drive Revit reliably from an application. The Revit API assumes that all interaction with the API functionality happens from within an external command. In general,... Read more →

Document IsModified Property

Looking at the Document.IsModified property, one quickly notices that it is frequently set, even if no real modifications have been applied to a document. One reason for this is that every execution of an external command returning IExternalCommand.Result.Succeeded will cause this property to return True. To explore this in detail, we can use the following minimal command implementation: public IExternalCommand.Result Execute( ExternalCommandData commandData, ref string message, ElementSet elements ) { Application app = commandData.Application; Document doc = app.ActiveDocument; Debug.WriteLine( string.Format(... Read more →