# Autocad Class Reference

> Quick reference for AutoCAD .NET API classes - 1,248 types across 28 namespaces

- Skill: `hebackus/autocad-class-reference` (Agent Skill)
- Install (CLI): `npx skillmds@latest add hebackus/autocad-class-reference`
- Raw SKILL.md: https://api.skillmd.com/api/skills/hebackus/autocad-class-reference/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Integrations & APIs
- Author: hebackus (https://skillmd.com/u/hebackus)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/hebackus/autocad-class-reference

---


# AutoCAD 2026 .NET API Class Reference

**Quick lookup for 1,248 classes across 28 namespaces**

## When to Use This Skill

- Looking for AutoCAD base classes
- Finding database entities (Line, Circle, Polyline, etc.)
- Checking geometry classes
- Finding editor/application classes
- Exploring runtime services

## Common Patterns

### Access Database and Transaction

```csharp
using Autodesk.AutoCAD.ApplicationServices;
using Autodesk.AutoCAD.DatabaseServices;
using Autodesk.AutoCAD.Runtime;

[CommandMethod("MYCOMMAND")]
public void MyCommand()
{
    Document doc = Application.DocumentManager.MdiActiveDocument;
    Database db = doc.Database;
    Editor ed = doc.Editor;

    using (Transaction tr = db.TransactionManager.StartTransaction())
    {
        // Work with database objects
        BlockTable bt = tr.GetObject(db.BlockTableId, OpenMode.ForRead) as BlockTable;
        BlockTableRecord btr = tr.GetObject(bt[BlockTableRecord.ModelSpace],
            OpenMode.ForWrite) as BlockTableRecord;

        tr.Commit();
    }
}
```

### Create Entity

```csharp
using (Transaction tr = db.TransactionManager.StartTransaction())
{
    BlockTable bt = tr.GetObject(db.BlockTableId, OpenMode.ForRead) as BlockTable;
    BlockTableRecord btr = tr.GetObject(bt[BlockTableRecord.ModelSpace],
        OpenMode.ForWrite) as BlockTableRecord;

    // Create a line
    Line line = new Line(new Point3d(0, 0, 0), new Point3d(100, 100, 0));
    line.ColorIndex = 1; // Red

    btr.AppendEntity(line);
    tr.AddNewlyCreatedDBObject(line, true);

    tr.Commit();
}
```

### User Input

```csharp
using Autodesk.AutoCAD.EditorInput;

Editor ed = Application.DocumentManager.MdiActiveDocument.Editor;

// Prompt for point
PromptPointOptions ppo = new PromptPointOptions("\nSelect point: ");
PromptPointResult ppr = ed.GetPoint(ppo);
if (ppr.Status == PromptStatus.OK)
{
    Point3d pt = ppr.Value;
}

// Prompt for entity
PromptEntityOptions peo = new PromptEntityOptions("\nSelect entity: ");
peo.SetRejectMessage("\nMust be a line.");
peo.AddAllowedClass(typeof(Line), true);
PromptEntityResult per = ed.GetEntity(peo);
if (per.Status == PromptStatus.OK)
{
    ObjectId lineId = per.ObjectId;
}
```

## Full Class Index

See [`../../autocad-api-reference/CLASS_INDEX.md`](../../autocad-api-reference/CLASS_INDEX.md) for complete listing of all 1,248 types.

## Related Skills

For Civil 3D-specific classes, use:
- `/c3d-api:c3d-class-reference` - Civil 3D classes
- `/c3d-api:c3d-root-objects` - CivilApplication/CivilDocument

For specific AutoCAD entity and API topics, use:
- `/c3d-api:acad-tables` - Creating and modifying AutoCAD table entities
- `/c3d-api:acad-geometry` - Working with geometric types (Point3d, Vector3d, curves)
- `/c3d-api:acad-mtext` - Creating and formatting MText entities
- `/c3d-api:acad-mleaders` - Creating and configuring MLeader entities
- `/c3d-api:acad-fields` - Working with AutoCAD field expressions
- `/c3d-api:acad-dimensions` - Creating dimension entities
- `/c3d-api:acad-hatches` - Creating hatch pattern fills
- `/c3d-api:acad-blocks` - Creating and inserting block references
- `/c3d-api:acad-sheet-sets` - Reading/writing Sheet Set (.dst) files via COM
- `/c3d-api:acad-layers` - Layer table, layer records, properties, and states
- `/c3d-api:acad-editor-input` - Editor prompts, selection sets, and filters
- `/c3d-api:acad-polylines` - Polyline, Polyline2d, Polyline3d entity details

## Documentation

- **HTML Docs:** `ac3d_netapi2docs/docs/AutoCAD_2026/html/index.html`
- **Source Code:** `ac3d_netapi2docs/src/AutoCAD_2026/`