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🎬 Demo Video

ExportCADX

Advanced Revit to DXF Geometry Exporter

ExportCADX is a Revit External Application allowing users to export specific Revit element categories (Walls, Windows, Structural Framing) into clean, mathematically precise DXF files. It utilizes the netDxf library to generate geometry and implements the MVVM pattern for a responsive, modern UI.

🚀 Features

• Selective Export: Target specific categories:
  • Walls: Exports face boundaries.
  • Windows: Exports family geometry (including nested instances).
  • Structural Framing: Exports beam geometry.
• Geometry Conversion: High-fidelity conversion of Revit geometry to DXF entities:
  • Revit.Line → DXF.Line / DXF.Ray
  • Revit.Arc → DXF.Arc / DXF.Circle
  • Revit.Ellipse → DXF.Ellipse
  • Revit.NurbSpline → DXF.Polyline3D (via tessellation)
• Modern UI: Built with WPF, MaterialDesign, and CommunityToolkit MVVM.

🛠 Tech Stack & Dependencies

Component	Technology
Platform	Autodesk Revit API (C#)
DXF Engine	netDxf
UI Pattern	MVVM (Model-View-ViewModel)
MVVM Lib	CommunityToolkit.Mvvm
UI Styling	MaterialDesignThemes

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📂 Project Architecture

1. Entry Point (MainCommand.cs)

The entry point implementing IExternalCommand. It initializes the ViewCommand (ViewModel) and launches the UserControl1 (View) as a dialog.

2. UI & ViewModels (Views/, ViewModels/)

Class	Description
ViewCommand.cs	The ViewModel. Handles UI logic, folder selection (FolderBrowserDialog), and commands (RelayCommand). It routes the export request to the logic layer.
UserControl1.xaml	The View. A WPF Window styled with Material Design. Contains inputs for Export Type, Folder Path, and Format selection (DXF/DWG/XML).
ExportRequest.cs	A simple Model class used to pass user selection data (ElementType, Format, Path) from the UI to the Exporter.

3. Core Logic (geoutills/)

This is the engine of the application, handling the translation of Revit geometry to .dxf format.

DXFGeomExporter

The main controller for the export process.

• Init(): Handles directory creation.
• ExportWallsByFaces: Iterates over Wall Solids → Faces → EdgeLoops.
• ExportFamilyInstancesByFaces: Handles geometry extraction for Windows and Framing, including nested geometry recursion.

netDxfEntityUtils

A static helper class that acts as the Geometry Bridge. It converts Revit mathematical objects into netDxf entities.

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🧩 Geometry Conversion Logic

The application uses a specific logic to handle complex Revit geometry:

// Pseudocode logic flow found in netDxfEntityUtils.cs

public static EntityObject Convert(GeometryObject revitGeo)
{
    if (revitGeo is Arc) 
    {
        // Calculate start/end angles relative to center
        // Return new netDxf.Entities.Arc();
    }
    else if (revitGeo is Line)
    {
        // Check if Bound (Line) or Unbound (Ray)
        // Return new netDxf.Entities.Line();
    }
    else if (revitGeo is NurbSpline)
    {
        // Tessellate points
        // Return new netDxf.Entities.Polyline3D();
    }
}

📥 Installation & Usage

1. Clone the repository.
2. Restore NuGet Packages:
   • netDxf
   • CommunityToolkit.Mvvm
   • MaterialDesignThemes
3. Build the solution (Ensure references to RevitAPI.dll and RevitAPIUI.dll are set to Copy Local: False).
4. Load the DLL into Revit using Add-in Manager or a .addin manifest.
5. Run the command MainCommand.

⚠️ Status

• ✅ DXF Export: Fully Implemented.
• 🚧 DWG Export: Placeholder (Not implemented).
• 🚧 XML Export: Placeholder (Not implemented).

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