This project explores the possibility run live Revit API C# code bundled with visualizations and explanatory text.

Amazing for rapid prototyping 🚀- preferably powered by LLM. It is perfect for knowledge sharing, teaching BIM concepts and API development. The variable-sharing feature in NET Interactive lets us code C# against Revit and then use Python in another kernel. It is the missing data-analysis tool for Autodesk Revit!

A preview release of the addin is available under releases. Revit 2023 and 2024 is supported.

• Download file msi or zip of the last release
• Install the Revit addin and open Revit
• "Interactive Revit Kernel" will show up in the Add-Ins tab
• Click on the button to show the Kernel UI.

You will also need a notebook environment. I recommend Polyglot Notebooks, an extension to Visual Studio Code but it is also possible to use Jupyter Notebooks.

• Install Visual Studio Code
• Goto extensions -> Install Polyglot Notebooks
• Polyglot Notebooks requires .NET 7 SDK

• Create a new notebook in VS Code.
• In Autodesk Revit, click start in the kernel UI

Add a new C#-code cell and install the revit kernel extension.

#r "nuget:RevitInteractive"

In another cell, use the #connect-directive to establish live connection to revit. Make sure to start the kernel first and specify the revit version.

#!connect revit --kernel-name revit --revit-version 2024

From now you'll be able to send code to Revit by starting the c#-cell with #!revit:

#!revit
var collector = new FilteredElementCollector( doc, uidoc.ActiveView.Id);

var query = collector
        .WhereElementIsNotElementType()
        .WhereElementIsViewIndependent()
        .ToElements();

var result = query.GroupBy(x => x.Category.Name).Select(y => new {
    Id = y.Key,
    Count = y.Count()
}).ToList();

display(result);
result

If you open a new model, you need to restart kernels in both notebook and in revit.

When using LLMs such as ChatGPT to write revit API Code for use in the notebook you would probably want to steer it's behaviour to minimize editing the code for use in an interactive context. See System Promts for some initial drafts.

Begin conversation by:

[SYSTEM] {System prompt text}

I will try to collect som fun examples. There is also a collection of tutorials in the folder. Extracting profile geometry from floor and export to shapefile for GIS-visualization using C# and Python (with Shapely and Geopandas).

See samples/GIS/GIS Visualization Building Footprint.ipynb

The Revit API is tightly coupled with the Revit UI and the Revit document data structures and operates on the assumption that it's being called within the same process where the UI and the document are loaded. This prevents you from calling the API from for example a polyglot notebook without some kind of middle-man or dispatcher.

NET interactive operates with kernels. A kernel is simply a process that receives execution instructions from clients and communicates the results back to them. The decopuled two-process model where you separate execution from evaluation allows for an approach where an evaluator can live inside Autodesk Revit as an addin and receives code from frontend clients such as Polyglot Notebook, Azure Data Studio or Jupyter.

In .NET Interactive a proxy kernel is a concept that describes a subkernel that proxies a remote kernel. We can add a proxy kernel to the composite kernel that routes commands to the actual implementation written as a Revit Addin. The revit addin implements a NET Interactive kernel process and executes code in the Revit API thread using external events(check Jeremy Tammik's arcticle External Access to the Revit API for more info on this topic).

However, due to the issues with third-party conflicts regarding the Roslyn API:s it was a hurdle to compile the code in the Revit addin so I tested to move the compilation before the code is sent to the embedded kernel in Revit. Technically, it is done using a registered middleware on the proxykernel that compiles the code and then send the path to the compiled assembly to the revit addin which loads it into memory and executes a method defined in a common interface with a list of common variables.

• IPython
• NET Interactive
• Literate Programming with LLMs
• Jupyter BIM
• ChatGPT System Prompts
• dnMerge

• Built on top of NET Interactive
• Got a lot inspiration from RevitAddinManager for how to configure csproj.
• Credit to Alexander Sharykin for his https://github.com/jowsy/RetroUI WPF theme (forked by me and adapted for use in a Revit addin).

MIT