AutoCAD .NET Plugin Template (Cursor)

A minimal .NET 8 class library template for developing AutoCAD/Civil 3D plugins with debugging support in Visual Studio Code with Cursor. This is based on the AutoCAD .NET Wizards template written by Madhukar Moogala

Video

https://www.youtube.com/watch?v=aX8c7zj9jGQ

Prerequisites

• .NET 8.0 SDK or later
• AutoCAD 2025/2026
• Visual Studio Code with C# extension or Cursor IDE
• (Optional) Civil 3D 2025/2026 for Civil 3D development

Quick Setup

1. Configure AutoCAD Paths

You need to update the AutoCAD path:

In AutoCADPlugin.csproj (for assembly references):

<!-- Edit these paths to match your AutoCAD installation -->
<AutoCADPath>C:\Program Files\Autodesk\AutoCAD 2025</AutoCADPath>

<!-- For Civil 3D, uncomment and edit this path -->
<!-- <Civil3DPath>C:\Program Files\Autodesk\AutoCAD 2025\C3D</Civil3DPath> -->

Common AutoCAD installation paths:

• AutoCAD 2026: C:\Program Files\Autodesk\AutoCAD 2026
• AutoCAD 2025: C:\Program Files\Autodesk\AutoCAD 2025

2. Build the Project

Open a terminal in the project directory and run:

dotnet build -c Debug -p:Platform=x64

The DLL will be created in bin\Debug\AutoCADPlugin.dll

Note: The build may also create a copy in bin\x64\Debug\, but use the bin\Debug\ path for NETLOAD.

3. Debug in Cursor/VS Code

1. Set breakpoints in Commands.cs (e.g., in the HelloCommand method)
2. Start AutoCAD or Civil 3D manually
3. In Cursor/VS Code, press F5 to attach debugger
4. Select the acad.exe process when prompted
5. In AutoCAD, type NETLOAD and browse to bin\Debug\AutoCADPlugin.dll
6. Test with commands: HELLO or DRAWCIRCLE

Your breakpoints will be hit!

Debugging Configuration

The template includes a simple "Attach to AutoCAD" configuration in .vscode/launch.json that works for both AutoCAD and Civil 3D.

Adding Civil 3D Support

To enable Civil 3D development:

1. Uncomment the Civil 3D path in AutoCADPlugin.csproj:

   <Civil3DPath>C:\Program Files\Autodesk\AutoCAD 2025\C3D</Civil3DPath>

2. Uncomment the Civil 3D references:

   <Reference Include="AecBaseMgd">
     <SpecificVersion>False</SpecificVersion>
     <HintPath>$(AutoCADPath)\ACA\AecBaseMgd.dll</HintPath>
     <Private>False</Private>
   </Reference>
   <Reference Include="AeccDbMgd">
     <SpecificVersion>False</SpecificVersion>
     <HintPath>$(Civil3DPath)\AeccDbMgd.dll</HintPath>
     <Private>False</Private>
   </Reference>

3. Use Civil3D-Metric or Civil3D-Imperial launch profile when debugging

Project Structure

AutoCADPlugin/
├── AutoCADPlugin.csproj      # Project configuration
├── Commands.cs               # Sample AutoCAD commands
├── Properties/
│   └── launchSettings.json  # Launch profiles
├── .vscode/
│   ├── launch.json          # Debug configuration
│   └── tasks.json           # Build tasks
└── README.md                # This file

Customization

Adding New Commands

Create new command methods in Commands.cs or new class files:

[CommandMethod("MYCOMMAND")]
public void MyCommand()
{
    Document doc = Application.DocumentManager.MdiActiveDocument;
    Editor ed = doc.Editor;
    ed.WriteMessage("\nMy custom command executed!\n");
}

Changing Target AutoCAD Version

1. Update the <AutoCADPath> in the project file
2. Ensure the AutoCAD .NET API version matches your target version

Troubleshooting

"Could not load file or assembly" error

• Ensure AutoCAD path is correct in the project file
• Verify you're building for x64 platform
• Check that the AutoCAD version matches the referenced DLLs

Breakpoints not hitting

• Ensure you're running in Debug configuration
• Check that the loaded DLL matches the one being debugged
• Try rebuilding the project and reloading in AutoCAD

Civil 3D specific issues

• Ensure Civil 3D is installed
• Verify the Civil 3D path is correct
• Use the appropriate Civil 3D launch profile

Additional Resources

• AutoCAD .NET Developer's Guide
• AutoCAD .NET API Reference
• Civil 3D .NET API Guide

License

This sample is licensed under the terms of the MIT License. Please see the LICENSE file for full details.

Written by

João Martins in/jpornelas , Autodesk Platform Services