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My First Revit Plugin Enhancements

Originally Published in

Today, let’s return to the recurring topic of getting started with the Revit API, its SDK samples, and programming in general:

My First Revit Plugin Enhancements

A couple of people recently mentioned issues getting started with the Revit API, e.g. in the Revit API discussion forum ↗ threads on Revit API Visual Studio error/warnings ↗ and IExternalCommand could not be found ↗.

There are several ways to quickly get started with the Revit API, which I present as completely and succinctly as I can in the getting started overview.

The first problem you might encounter is getting your add-in loaded into Revit.

That is simple to resolve once you understand what is going on.

Once way is to follow the developer guide section on getting started ↗ and work through the hello world samples presented there.

Another way is to follow the My First Plugin video tutorial ↗.

Elie Accari ↗ very kindly shared a couple of valuable enhancement suggestions for it in his thread on My First Plugin – quick modification ↗:

I refer to the high entropy body of knowledge in My First Plugin ↗.

Other threads mentioned issues some users are facing getting the plugin to work.

The above linked page includes a feedback email which has bounced back (“myfirstplugin wasn’t found at autodesk.com”), so I am posting here in case new users seek to implement the same modification.

Issue #1: Location of the Plugin

Not all users have access to the AddIns folder in Program Files, but all users have access to the _%AppData%\Roaming\Autodesk\Revit\addins_ folder. If this is mentioned in the tutorial, it can reduce the number of questions asked.

Issue #2: Unfamiliar Behaviour

The code does not properly copy the group. It just places it where you click, which could be in the middle of the other room. A more familiar way is to do a Copy-From:-To:. Only 3 lines of code including 2 modifications are required.

Modification #1: Pick 2 points and calculate the distance between the two, instead of picking only 1 point.

To do so, replace the following code in the original lesson:

  //Pick a point
  XYZ point = sel.PickPoint("Please pick a point to place group");

With the following:

  //Pick a point
  XYZ pointFrom = sel.PickPoint("Pick a point to copy From");
  XYZ pointTo = sel.PickPoint("Pick a point to copy To");
  //Calculate the distance between the two points
  XYZ ptDist = pointTo - pointFrom;

Modification #2: Use the Copy method instead of Place

Replace the following line between the trans.Start and trans.Commit lines:

  doc.Create.PlaceGroup(point, group.GroupType);

With this line:

  ElementTransformUtils.CopyElement(doc, elem.Id, ptDist);

Finally, a suggestion: the text seem to entice Revit users into programming. In this regard, I would consider doing the following:

Add Lesson 0 (or renumber the lessons): Implement the same code in a macro using the Edit / SharpDevelop IDE readily accessible from inside Revit, without going to Microsoft Visual Studio.

Then Lesson 1 could become: Now let’s do this again by converting this macro into an add-in.

Ever so many thanks to Elie for his constructive criticism and extremely helpful advice and suggestions!

I passed it on to my colleagues for consideration next time the tutorial is re-recorded.

Getting Started with Web Programming – FreeCodeCamp

By the way, in case you are interested in getting started with web programming in addition to the desktop and .NET based Revit API, I can recommend the training sequence provided by freeCodeCamp ↗ covering the following list of topics:

freeCodeCamp

  • Front End Development Certification
    • HTML5 and CSS
    • Responsive Design with Bootstrap
    • jQuery
    • Basic Front End Development Projects
    • Basic JavaScript
    • Object Oriented and Functional Programming
    • Basic Algorithm Scripting
    • JSON APIs and Ajax
    • Intermediate Front End Development Projects
    • Intermediate Algorithm Scripting
    • Advanced Algorithm Scripting
    • Advanced Front End Development Projects
    • Claim Your Front End Development Certificate
  • Data Visualization Certification
    • Sass
    • React
    • React Projects
    • D3
    • Data Visualization Projects
    • Claim Your Data Visualization Certificate
  • Back End Development Certification
    • Automated Testing and Debugging
    • Node.js and Express.js
    • Git
    • MongoDB
    • API Projects
    • Dynamic Web Application Projects
    • Claim Your Back End Development Certificate
  • Video Challenges
    • Computer Basics
    • The DOM
    • JavaScript Lingo
    • Chrome Developer Tools
    • Big O Notation
    • Accessibility
    • Agile
    • Computer Science
    • Data Visualization
    • Embedded and Internet of Things
    • Game Development
    • Gamification
    • Machine Learning
    • Math for Programmers
    • Mobile JavaScript Development
    • DevOps
    • Software Engineering Principles
    • Statistics
    • Tools
    • User Experience Design
    • Visual Design
  • Open Source for Good
  • Coding Interview Preparation
    • Coding Interview Training
    • Mock Interviews

If you are a complete beginner undecided what language to start with, the 11-minute video on what programming language should I learn? Front-end? Back-end? Machine learning? ↗ might help:

ModelessForm_ExternalEvent Initialisation

Before closing, let me mention another little hint resolving an issue encountered by Aziz ↗ in the ModelessForm_ExternalEvent SDK sample ↗:

Question: I am new to develop in Revit API getting started tutorials and all is going well until now, when I started with the SDK samples.

I am just trying to implement the ModelessForm_ExternalEvent sample, but it keeps throwing me an exception stating that Object reference not set to an instance of an object.

Answer: However, after more trials, I tried to change something and it did magically work. I created a class instance from but not assigning it a null value. I am sharing it below in case someone else is experiencing the same issue:

  // class instance
  Public static Application thisApp = new Application();