# C3d Class Reference

> Quick reference for Civil 3D .NET API classes - instant class lookups

- Skill: `hebackus/c3d-class-reference` (Agent Skill)
- Install (CLI): `npx skillmds@latest add hebackus/c3d-class-reference`
- Raw SKILL.md: https://api.skillmd.com/api/skills/hebackus/c3d-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/c3d-class-reference

---


# Civil 3D .NET API Class Reference

**Quick lookup for 959 classes across 19 namespaces**

## When to Use This Skill

- Looking for a specific class name
- Checking what classes exist in a namespace
- Finding the right type for a task
- Exploring available API surface

## Core Namespaces (384 classes)

### Autodesk.Civil.DatabaseServices

**Main Civil 3D objects** - Alignments, Surfaces, Profiles, Pipe Networks, etc.

### Autodesk.Civil.DatabaseServices.Styles (163 classes)

**Styles for all Civil 3D objects**

### Autodesk.Civil (241 classes)

**Core types, enumerations, exceptions**

### Autodesk.Civil.Settings (86 classes)

**Drawing and object settings**

### Autodesk.Civil.ApplicationServices (1 class)

## Common Patterns

### Get CivilDocument
```csharp
using Autodesk.Civil.ApplicationServices;

CivilDocument civilDoc = CivilApplication.ActiveDocument;
```

### Access Collections
```csharp
using Autodesk.Civil.DatabaseServices;

ObjectIdCollection alignmentIds = civilDoc.GetAlignmentIds();
ObjectIdCollection surfaceIds = civilDoc.GetSurfaceIds();
ObjectIdCollection networkIds = civilDoc.GetPipeNetworkIds();
ObjectIdCollection pressureNetworkIds = civilDoc.GetPressurePipeNetworkIds();
```

### Open Objects
```csharp
using (Transaction tr = db.TransactionManager.StartTransaction())
{
    Alignment align = tr.GetObject(alignmentId, OpenMode.ForRead) as Alignment;
    Surface surf = tr.GetObject(surfaceId, OpenMode.ForRead) as Surface;

    tr.Commit();
}
```

## Full Class Index

See [`api-reference/CLASS_INDEX.md`](../../api-reference/CLASS_INDEX.md) for complete listing of all 959 types.

## Related Skills

- `/c3d-api:c3d-project-setup` - Setting up .NET project for Civil 3D development
- `/c3d-api:c3d-root-objects` - CivilApplication, CivilDocument, settings hierarchy
- `/c3d-api:c3d-alignments` - Alignment creation, entities, geometry
- `/c3d-api:c3d-surfaces` - Surface creation, editing, data extraction
- `/c3d-api:c3d-profiles` - Profile layout, PVIs, profile views
- `/c3d-api:c3d-pipe-networks` - Gravity and pressure pipe network objects
- `/c3d-api:c3d-corridors` - Corridor creation, baselines, regions
- `/c3d-api:c3d-points` - CogoPoint, PointGroup, UDP access
- `/c3d-api:c3d-label-styles` - LabelStyle, components, hierarchy
- `/c3d-api:c3d-custom-subassemblies` - Subassembly SDK, CorridorState, geometry callbacks