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acad-regions-solids

Create and manipulate regions and Solid3d objects in AutoCAD Civil 3D.

3|Updated Feb 17, 2026
Search Tags:#transformation#regions#autocad#brep#extrusion#solid3d#boolean-operations
One-click install
npx skills add https://github.com/hebackus/c3d-api-plugin --skill acad-regions-solids
Or copy as Structured Prompt for Agent▼
Please help me install this Agent Skill.
Skill: acad-regions-solids
Source: https://github.com/hebackus/c3d-api-plugin/tree/main/skills/acad-regions-solids
Command: npx skills add https://github.com/hebackus/c3d-api-plugin --skill acad-regions-solids

SYSTEM DOCUMENTATION & REQUIREMENTS

What problem does it solve?

Regions and 3D solids in AutoCAD/Civil 3D can be complex to create and modify; this skill consolidates operations for region creation, boolean operations, and solid workflows including extrusions, revolutions, sweeps, lofts, and Brep access into repeatable patterns.

Core Features & Use Cases

  • Region creation from closed curves using Region.CreateFromCurves.
  • Region Boolean Operations (BoolUnite, BoolSubtract, BoolIntersect) to combine or cut regions.
  • Solid3d primitives and positioning using TransformBy (box, sphere, cylinder, cone, torus, wedge, pyramid).
  • Solid creation workflows: Extrusion, Revolution, Sweep, Loft with cross-sections and paths.
  • Brep API access for per-face/edge/vertex topology exploration and property queries.
  • Mass properties access (volume, centroid, moments; and radii of gyration, principal directions).
  • Coordinate system transforms and alignment with UCS or custom matrices.

Quick Start

Create a simple region from a closed boundary, extrude it into a Solid3d, and then apply a boolean subtraction with a second solid.

Frequently Asked Questions about acad-regions-solids

High-intent search queries and answers about installing and using this skill.

FAQPage Schema
How do I create a 3D solid from a closed boundary in AutoCAD?▼

To create a 3D solid from a closed boundary in AutoCAD, you first generate a region from closed curves, then extrude that region into a Solid3d object using extrusion workflows.

Can I perform boolean operations on regions and Solid3d objects programmatically?▼

Yes, boolean operations support combining or cutting both regions and Solid3d objects. You can use BoolUnite, BoolSubtract, and BoolIntersect to modify 2D regions and 3D solids.

How do I access per-face and edge topology of a Solid3d in AutoCAD?▼

You access per-face, edge, and vertex topology of a Solid3d using the Brep API. This allows detailed property queries and sub-entity exploration across 3D solid workflows.

What is the best way to align 3D solid primitives using coordinate systems in AutoCAD?▼

The best way to align 3D solid primitives is using TransformBy with coordinate systems and custom matrices. This handles positioning for boxes, spheres, cylinders, and other solid primitives.

How do I calculate mass properties like volume and centroid for AutoCAD solids?▼

You calculate mass properties for AutoCAD solids by accessing built-in property queries. This returns volume, centroid, moments, radii of gyration, and principal directions for Solid3d objects.

What solid creation workflows are available for AutoCAD Civil 3D beyond simple extrusions?▼

Beyond simple extrusions, AutoCAD Civil 3D solid creation workflows include revolution, sweep, and loft operations. These use defined cross-sections and paths to generate complex Solid3d geometry.

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