The Building Coder

Determining Maximal Flow in HVAC Duct Connectors

A colleague came up with a request for a simple Revit MEP HVAC utility add-in that I would like to present. Question: We need to extract some specific ductwork values in Revit MEP and report them to the user. To begin with, all we need is the largest flow value on each duct, exported to a shared parameter on the duct. The purpose of the routine is for the users to confirm their duct sizing with this data reflecting the... Read more →

User MEP Calculation Sample

One of the main new features in the Revit 2014 API is the possibility to make use of external services to redefine the algorithms used for certain MEP related calculations. The external services framework was introduced in Revit 2013, but not used in that version. The recent listing of Revit 2014 API functionality and SDK samples points out that this is one of the highlights of the new API, and yet no sample using it has been published yet. Let's... Read more →

Football and Space Adjacency for Heat Load Calculation

Here is a summary of a discussion with Jasper Desmet, who is studying engineering and working on a research project for his master thesis concerning heat load calculation using BIM software, proving that it is possible for a novice programmer to extract the required information from the model using the Revit API. Football Tournament, Fleece and Shard First, though, let me mention that I visited the UK this weekend to participate in the Autodesk European soccer tournament, which took place... Read more →

Recursively Disable Architecture Mismatch Warning

I recently explained the cause and resolution of the processor architecture mismatch warning MSB3270. On closer consideration, I decided to fix it for all the ADN training material labs and samples, and actually for the entire collection of Revit SDK samples as well. This is obviously not something you want to do manually, considering that it involves a modification of hundreds of project files. Here are the steps involved in automating and testing this process: Disable mismatch warning utility Project... Read more →

Dynamically Hide and Display a Ribbon Panel

Here is a quick little question on dynamically toggling the display of a custom ribbon panel, e.g. depending on the currently activated Revit disciplines. First, however, let me share this nice and wise little quote regarding the current weather situation and actually life and happiness in general from the German humourist Karl Valentin (1882-1948): I am happy if it rains – because if I am unhappy, it still goes on raining (Ich freue mich, wenn es regnet – denn wenn... Read more →

Sun Direction, Shadow Calculation and Wizard Update

I enjoyed some wonderful hot sunny days since I returned from New England back to Switzerland. Summer finally arrived. A nice change after the rain and cold both here and in New Hampshire and Massachusetts. Talking about rain and sun leads up nicely to today's topic, on the sun direction and shadow calculation in a Revit BIM. Before I get to that, though, I present an update of my Revit add-in wizards resulting in part from yesterday's post on the... Read more →

The ADN Sample AdnRme for Revit MEP 2014

I am back safe and sound in Europe again, and the pressure to complete my preparations for the upcoming Moscow Revit DevCamp on June 25th and the Revit 2014 API training in Sydney in July is gradually growing. As part of the preparation, I recently migrated the The Building Coder samples and the ADN Revit API training labs to Revit 2014, followed up by fixing most deprecated API usage warnings generated by The Building Coder samples. I now also addressed... Read more →

What's New in the Revit 2014 API

Here is one post that I prepared well for in advance, by publishing the previous 'What's New in the API' sections two months back: What's New in the Revit 2010 API What's New in the Revit 2011 API What's New in the Revit 2012 API What's New in the Revit 2013 API The information provided here is extracted from the document 'Revit Platform API Changes and Additions.docx' provided with the Revit SDK. It is also included in the 'What's New'... Read more →

Adjustable Versus Perpendicular Spud

I recently presented an explanation of some Revit MEP family editor part type classes, which led to a follow-up: Question: Thank you for the detailed answer about the duct fittings. I have a similar problem with one of the pipe fittings, namely spud. I know what a spud is, but not the difference between an adjustable and a perpendicular one. Can you explain the actual difference, please? Here is an image with some different spuds that I collected: Answer: Spuds... Read more →

Simple MEP System Traversal

Here is a simple MEP system traversal implementation that especially addresses the issue of determining what equipment is connected to the systems. The following read-only external command traverses all MEP systems in the document, using the MEPSystem.Elements property to retrieve most of the desired elements with very little effort. More than half the code is actually fussing about with formatting the result: [Transaction( TransactionMode.ReadOnly )] public class Command : IExternalCommand { static string PluralSuffix( int n ) { return 1... Read more →

Content Localisation

How to manage families and content creation is a crucial topic for a large number of Revit add-ins. Brian Johnson, technical specialist on structural engineering solutions at Autodesk in Austin, Texas, discusses how to efficiently address some important aspects of this below. First, however, let me wish everybody a Happy New Year of the Snake! A year for reflection, planning and searching answers. A good time for shrewd dealings, political affairs and coups d'état. People will be more likely to... Read more →

AU Classes on the View, MEP and Link APIs

Wednesday was my first normal and full AU day, after completing the developer conference and DevLab activities. I was able to attend two interesting classes held by Revit API developers Steven Mycynek and Arnošt Löbel, and present my own Revit MEP API one. Here they are in chronological order: CP3133 Using the Revit Schedule and View APIs by Steven Mycynek CP4108 Revit MEP Programming: All Systems Go by Jeremy Tammik CP3455 Managing Revit Links with the Revit API by Arnošt... Read more →

Sweep PickPath Tolerance Criteria

Here is a rather specialised and hitherto undocumented topic of great importance to anyone trying to model precise complex swept geometry. The issues below arose exploring the tolerance requirements of the 'Pick Path' options in the Revit UI, which map to the ReferenceArray and Reference input to the two FamilyItemFactory API calls for generating this kind of geometry: Sweep NewSweep( bool isSolid, ReferenceArray path, SweepProfile profile, int profileLocationCurveIndex, ProfilePlaneLocation profilePlaneLocation ); SweptBlend NewSweptBlend( bool isSolid, Reference path, SweepProfile bottomProfile, SweepProfile... Read more →

Updated Revit MEP 2013 Material

I presented the Revit MEP API at the AEC DevCamp in June. In preparation for that, I provided a quick Revit 2013 MEP API overview and migrated and more fully described the AdnRme sample application. I will be presenting on this topic again at Autodesk University in November, so I revisited the material and fleshed out the description of the Revit 2013 changes a bit more. Here is the completed overview: The Revit MEP 2013 API The information provided in... Read more →

Elbow Fitting Selection and Dimensioning

Vacation time is approaching fast for me and lots of things need finishing off beforehand. Meanwhile, one thing that had a number of developers champing at their bits for a while now finally came to fruition: Autodesk Exchange The Autodesk Exchange store is now open for application submissions. Stephen Preston already published several articles exaplaining the full details: Summary information Information for Revit developers Publishing an app Here is another topic that recently kept me busy, with some helpful input... Read more →

DevCamp Day Two

This morning I presented my second session, on some of the Revit 2013 UI API enhancements, in the Revit API beginner track. After that, I returned back to the Revit API expert one to attend the presentations on modeless interaction and IFC before presenting my final session on the Revit MEP API. Here then are my sessions of today, in chronological order: 1-4 Revit 2013 UI API enhancements 2-3 Asynchronous interactions 2-2 IFC export open source 2-7 Revit MEP API... Read more →

Family Instance Element Coordinate System

I spent last weekend in Sweden for my 35 year school anniversary, having graduated from the German school in Stockholm in May 1977. The day after our reunion I visited a friend's summer house on the little lake Kvarnsjön in Huddinge: Back to the Revit API, after having taken a second look at connector orientation, here is another MEP coordinate system topic that can bear updating and coincidentally also has a connection to Scandinavia, since Progman Oy and Olli are... Read more →

Connector Orientation

Today is the Pentecost or Whit Monday holiday in Neuchâtel, and I am in full tilt preparing for the AEC DevCamp in Waltham next week. I will be presenting sessions on the new Revit 2013 UI API features, the Revit MEP API, and extensible storage. I am of course looking forward much more to the many exciting other presentations by my colleagues in the ADN DevTech AEC team and especially by members of the Revit development team, directly from the... Read more →

Pipe Insulation and Insulation Material

I recently looked at the Revit MEP 2013 API and migrated the AdnRme sample to it. To follow up on that, here is an unexpectedly hard Revit MEP 2013 question by Victor Chekalin, who recently created the nice DataStorage sample. The new question leads to some tricky and interesting aspects on how to access data or database elements through the Revit API that are not immediately accessible via the expected route or "normal" channels. Where there's a will, there's a... Read more →

Create a Pipe Cap

Happily mixing the different Revit versions, let me follow up my work on the Revit MEP 2013 API and the updated AdnRme sample by another MEP related topic. Before getting to that, though, here is a brief heads-up for a new technology preview on Autodesk Labs: BIM Coordinator The effective organization of project data in shared or related coordinates is essential to effective collaboration across disciplines and good quality project information. BIM Coordinator for AutoCAD Civil 3D and Revit is... Read more →

The ADN MEP Sample AdnRme for Revit MEP 2013

Yesterday I discussed the Revit 2013 MEP API and the external services framework. In preparation for my Revit MEP API presentation at the upcoming AEC DevCamp in Boston in June, I also migrated the ADN MEP API sample AdnRme to Revit MEP 2013. The initial flat migration was extremely straightforward with zero code changes required. I obviously had to change the Revit API assembly references, which forces an update of the .NET framework version to 4.0. After bumping the framework... Read more →

The Revit 2013 MEP API and External Services

I mentioned a few MEP-specific enhancements in the Revit 2013 API. To recap, the enhancements include: Access to routing preferences, selection of pipe sizes, materials, fitting types, and the RoutingPreferenceTools SDK sample demonstrating its use Pipe and duct friction factors MEPSection base class for duct and pipe sections Viscosity and density at specified temperatures, new FluidType and enhanced FluidTemperature classes Read and write access to panel schedule spare circuit values Access to localized user-visible display strings for enumeration values via... Read more →

New Revit 2013 SDK Samples

Revit 2013 has been released, and I presented an overview of the Revit 2013 API two days ago. As always, the use of most of the API features is demonstrated by various SDK samples. For a better understanding of the use and contents of the Revit SDK in general, please refer to the getting started and self-preparation guides. Here is an overview of the new samples: ModelessForm_ExternalEvent and ModelessForm_IdlingEvent (ModelessDialog) ProgressNotifier (Events) RoutingPreferenceTools UIAPI WorkThread (MultiThreading) These samples are all... Read more →

Retrieve Geometry in Element Coordinate System

I am travelling rather further afield than usual today, and actually have been doing so all day yesterday as well. My normal paths remain inside of Europe, with occasional trips once or twice a year to the USA, for AEC DevCamp and Autodesk University. Now, exceptionally, I am on my way to Melbourne, Australia, to present a Revit API training and DevCamp next week. Meanwhile, here is an interesting little issue brought up by Olli Kattelus, software developer of MagiCAD... Read more →

Split a Duct or Pipe

Here is another short and sweet answer to a question that keeps popping up regularly: Question: How can I change the length of a pipe using the Revit MEP API? I am actually interested in programmatically splitting the pipe, but I cannot see any support for this in the API. I tried to change the length of the pipe to indirectly cause a split, but the LocationCurve.Length property is read-only, so I cannot simply modify it. Answer: I touched briefly... Read more →

Hosting a Light Fitting on a Reference Plane

It is sometimes a challenge to determine which of the numerous overloads of the NewFamilyInstance method to use to achieve a desired effect. Here is a question on using it to host a light fitting by Simon Jones, with an initial answer by Saikat Bhattacharya, followed by lots more research by Simon to nail down the right solution that really works. Question: How can I host a light fitting onto a reference plane? I tried several different ways without any... Read more →

Access Wire Sizes

Here is an interesting question that came up regarding the access to wire sizes. Using a filtered element collector to retrieve a TemperatureRatingType instance and attempting to read its wire sizes produces a problem that is in fact documented in the Revit API help file RevitAPI.chm, but the workaround is still worth pointing out. Question: I'm trying to access the wire size settings in a Revit model without success. The following code throws an exception saying "Object reference not set... Read more →

Retrieving Duct and Pipe Endpoints

Here is a very basic question that may still stump a newcomer to the Revit MEP API: Question: I have just started to learn the MEP API and I am struggling with a problem, which I thought would be fairly easy, but after a day and a half I guess not. I need to iterate through ducts (done that bit), then decide if it's a round duct (done that too). Then I want to get the plan view coordinates in... Read more →

Set New Pipe Type Properties

Here is an interesting Revit MEP API question on setting the preferred elbow, tee and junction type information after creating a new Revit MEP pipe type, answered by my colleague Joe Ye in Beijing: Question: I am creating a new Revit MEP pipe type by filtering for all element types of the category OST_PipeCurves and selecting the one named "Standard". On the resulting new ElementType instance, I would like to define the preferred settings as follows: Change the preferred elbow... Read more →

Modeless Loose Connector Navigator Update

Here is an update to my modeless loose connector navigator, which I created as a sample application to demonstrate how to set up a modeless dialogue to drive Revit using the Idling event. Please refer to the original post for a full description. The original Revit 2011 version had one flaw: the external command it implements subscribes to the Idling event. That means that a new subscription is added for every call to the command. Also, the subscription was never... Read more →

MEP Sample Code for Revit 2012

One of my sessions at Autodesk University 2011 is CP4453 Everything in Place with Revit MEP Programming. It will cover both the new Revit MEP 2012 API features and the Revit MEP API in general. In preparation for that, as well as preparing new samples, e.g. on placeholder elements, I am also updating the existing material, especially the ADN Revit MEP sample code. The old Revit 2011 material from AU 2010 is available online, for instance from the list of... 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 →

Modifying Cable Tray Shape

Question: I am able to successfully duplicate cable tray family types via the Revit API. I would like to use that feature to duplicate an existing cable tray family type and then change the shape of a given cable tray to the new type. So far, I have not been able to find any API methods to achieve this. Is it possible? If so, how, please? Answer: There is nothing special at all about changing the cable tray type from... Read more →

The Revit MEP 2012 API

The Revit 2012 API includes a number of important MEP specific enhancements, some completely new APIs have been added which are especially useful in the MEP domain, and last but not least, all of the many significant Revit platform enhancements are useful for MEP as well. The major Revit MEP enhancements include: Placeholder ducts and pipes Duct and pipe insulation and lining Read and write access to MEP pipe settings and sizes A number of minor enhancements have also been... Read more →

Improved MEP Element Shape and Mount Ararat

We recently talked about distinguishing Revit MEP duct element shapes, and Max aka Maciej Szlek presented a solution based on the analysis of the string value of the duct's Size parameter. I suggested that the algorithm might be improved, both to make it more general and robust and also to remove the dependency on the different string formats used for imperial and metric units. It probably becomes more efficient as well, by the way. Instead of looking at the duct... Read more →

Nested Lighting Fixture Instances

We already looked at a couple of aspects of nested family instances, such as access to nested instance geometry, creating nested families and determining whether a family instance is nested. Now Joel Spahn of Lighting Analysts, Inc. submitted a comment on the nested family utility methods raising a new question related to nested lighting fixtures, efficiently resolved by Harry Mattison of the Revit development team: Question: I have adapted this code to extract nested family instances and it works beautifully.... Read more →

Use of NewTakeOffFitting on a Pipe

I presented an example of using the NewTakeOffFitting method on a duct a while back. The original question, however, was actually related to inserting a break into a pipe. That turned out to be a bit more tricky. This was also discovered by Kailash Kute, who posted a whole series of comments on the topic. I will herewith reiterate my first answer to him and post the code that I had working to see whether that will help us move... Read more →

ASHRAE Viewer Plugin of the Month

We recently published our first ever Revit plugin of the month, for March, Adam's Room Renumbering add-in. Now the second one is already available on Autodesk Labs as well, for April, an ASHRAE Viewer for Revit MEP by Martin Schmid of Autodesk's AEC Industry Success team: The download includes ready compiled versions for both Revit 2011 and 2012, a complete user manual, and full source code, so you can use it as is, tweak it for your specific needs, or... Read more →

Distinguishing MEP Element Shape

Normally, when given a family instance, you can access the family name to obtain some information about it. For Revit MEP ducts, however, the duct shape is determined by an internal system family whose name is visible in the user interface but is not accessible through the API. For instance, with ducts, you cannot access the family of a round duct. In the user interface, it appears to belong to a family named "Round Duct", but in fact this built-in... Read more →

Create a Pipe Cap

Things have been a bit hectic for me in the last few days, with several complex cases to solve. I also suddenly and unexpectedly had to find out how to apply for a visa to Saudi Arabia, which is a kind of interesting process. Apparently, you start out with the inviting company in Saudi Arabia, which has to issue an invitation letter. This has to include a reference number, for which a form needs to be filled in and submitted... Read more →

Use of NewTakeOffFitting on a Duct

Here is a simple question on how to create a new MEP takeoff on a duct using the NewTakeOffFitting method: Question: I have a duct in my Revit MEP model and I want to create a takeoff fitting at its midpoint. I see that the method NewTakeOffFitting takes two arguments, a connector and an MEP curve, and returns a new family instance. My question is: How can I create the connector and curve? Can you show me some code on... Read more →

Unit Conversion and New Blogs

Quite a while back, I published a unit conversion utility for Revit 2010. Let's take a fresh look at that, and also at a couple of new Revit blogs. We discussed a couple of other issues related to units since then, such as the unit suffix and ProjectUnit SDK sample and a look at voltage units. The latter also includes an overview of some other unit related posts. Anyway, Rod Howarth picked up on the unit converter utility and ported... Read more →

Setting Duct Width and Height Requires Regeneration

Whenever you have a problem modifying or querying the model with your Revit plug-in, one of the first things to check is always your regeneration mode. If you are using the manual regeneration option, you need to check whether you possibly omitted a required intermediate regeneration call. It seems that there can never be enough reminders of this. Here is another case at hand: Question: I am sizing rectangular duct fittings through the API, and I noticed that the different... Read more →

Ray Tracing to Place Family Instance

Jeremiah Farmer of Land F/X recently presented his solution for placing a site component on a topo surface. One important issue in addition to the information presented there is that the family instance insertion point needs to be located on the surface. One way to find a suitable point is to use the Revit API method FindReferencesByDirection to shoot a ray through the model to determine a suitable point, i.e. the intersection point between the ray and the surface. If... Read more →

Project Vasari API

I mentioned the Autodesk Project Vasari last week, and the first question from Fernando Malard was whether it also provides an API. The question makes a lot of sense on this blog, since everything we discuss here is related to the Revit API. I thought Vasari would be an exception. Surprisingly, this is not the case. Ritchie Jackson asked the same thing, and received the following very satisfying reply from Matt Jezyk: Question: Vasari has the potential to be a... Read more →

Connector Direction and CreateAirHandler Sample

Here is an update to the CreateAirHandler SDK sample provided by my colleague Greg Wesner together with an interesting analysis of MEP connector directions. We looked at various aspects of MEP connectors several times in the past: The difference between the family connector elements and the project connector class. Enhancing RevitLookup for MEP, previously known as RvtMgdDbg. Connector orientation. Retrieving MEP elements and connectors. Modeless loose connector navigator. The CreateAirHandler SDK sample shows how to create an MEP air handling... Read more →

Autodesk Project Vasari

Autodesk Project Vasari is an easy-to-use, standalone design tool with analysis capabilities available via the cloud, built on the same technology as Revit, aimed at architectural designers and building energy analysts. It is focused on conceptual building design using both geometric and parametric modelling and supports performance-based design via integrated energy modelling and analysis features. It is compatible with Revit in that files created with it can be opened using Revit 2011, and vice versa. There are some limitations in... Read more →

Autodesk University 2010 Class Materials

I submitted the materials for my three Autodesk University classes yesterday. I checked the enrollment numbers at the same time and was a bit surprised: CP228-2 Optimal Use of New Autodesk Revit 2011 Programming Features, on Revit 2011 API features in general and the Idling event in particular: 154. CP234-2 Exactly What You Want and Faster: Autodesk Revit 2011 Programming Optimization, on optimisation and benchmarking, especially filtering: 135. CP316-3U All Systems Go in Autodesk Revit MEP Programming, an 'Unconference' together... Read more →

Autodesk University 2010 Classes

Kean's post on AU 2010 classes yesterday reminded me that I might mention my upcoming classes here as well. The catalogues of both physical and virtual classes have been posted to the AU website: My classes are the following: CP228-2: Optimal Use of New Autodesk Revit 2011 Programming Features, a lecture on Revit 2011 API features in general, on Tuesday 2010-11-30 14:00-15:00. CP234-2: Exactly What You Want and Faster: Autodesk Revit 2011 Programming Optimization, a lecture on Revit 2011 API... Read more →

Flex Duct Start Tangent

Still zipping around in Pattaya with my brother Marcus, and still blogging a bit now and then as well ... Here is a suggestion for a workaround to specify the start and end tangents of a flex duct or pipe that evolved through a recent exchange of comments with Zhu XiaoMeng: Question: In the Revit application UI, I can create a FlexDuct properly with the start tangent of the Hermite curve in a reasonable direction. But when I create a... Read more →