#### Overview of this book

AutoCAD is a computer-aided design (CAD) and drafting software application. AutoCAD supports both 2D and 3D formats. AutoCAD is used in a range of industries and is utilized by architects, project managers, and engineers, among others."Autodesk AutoCAD 2013 Practical 3D Drafting and Design" will take you beyond the 2D frontier and help you create accurate 3D models that simulate reality. This book is crammed full of creative and practical tutorials which will help you master the third dimension. From exercises on coordinate systems to creating solids and surfaces from 2D, you will wonder how you ever designed without this resource by your side."Autodesk AutoCAD 2013 Practical 3D Drafting and Design" is full of hands-on studies and projects that will help develop your 3D skills. Starting from the assumption of only a very basic knowledge of AutoCAD, this book will help you master 3D visualization and coordinate systems, create 3D models from 2D drawings, and from basic shapes, measure volumes, and other information, obtain 2D construction drawings from 3D models as well as how to apply lights and materials to get photorealistic images.
Autodesk AutoCAD 2013 Practical 3D Drafting and Design
Credits
www.PacktPub.com
Preface
Free Chapter
Introduction to 3D Design
Visualizing 3D Models
Coordinate Systems
Creating Solids and Surfaces from 2D
3D Primitives and Conversions
Editing in 3D
Editing Solids and Surfaces
Inquiring the 3D model
Documenting a 3D Model
Rendering and Illumination
Materials and Effects
Meshes and Surfaces
Final Considerations
Index

## Composite objects

Until now, we dealt with the creation of 3D objects. Now, let's see how to combine and modify them.

### Unions, subtractions, and intersections

Three basic operations to combine objects are unions, subtractions, and intersections. These are called Boolean operations and can be applied to solids, surfaces, and regions.

The commands to perform unions, subtractions, and intersections can be found on the ribbon, Home | Solid Editing panel, on the Modeling toolbar, and on the Menu bar, Modify | Solid Editing:

#### The UNION command

The `UNION` command (alias `UNI`) joins two or more objects into one. The command can be applied to solids, surfaces, and regions, but it only joins objects of the same type, that is, it can't join solids with surfaces or regions. It only prompts for the selection of objects to join and returns only one object:

```Command: UNION
Select objects: Selection
```

Duplicated volumes or areas are removed.

The command can be applied to solids that do not share a common volume or regions...