Chapter OneStarting to Draw
IN THIS CHAPTER
Getting acquainted with AutoCAD and AutoCAD LT
Starting a new drawing
Exploring the AutoCAD and AutoCAD LT interface
Storing your drawing
Closing a drawing and exiting AutoCAD and AutoCAD LT
In this chapter, I explain the essentials that you need to start drawing. After a little background, I discuss the basics of the screen that you see when you open AutoCAD or AutoCAD LT, and how to use it. If you've never used AutoCAD before, do the "Quick Start: Drawing a Window" chapter first.
AutoCAD and its younger sister, AutoCAD LT, are both created by Autodesk. Together they are the most widely used technical drawing programs anywhere. AutoCAD alone has more than 6,000,000 registered users. According to Autodesk, CAD stands for computer-aided design, but it can also stand for computer-aided drafting or drawing.
The first version of AutoCAD, running under DOS, came out in 1982. AutoCAD was the first significant CAD program to run on a desktop computer. At the time, most other technical drawing programs ran on high-end workstations or even mainframes. AutoCAD LT was introduced in 1993, as a less expensive alternative to AutoCAD, for people who don't need all of AutoCAD's advanced features.
Exploring AutoCAD's Advantages
AutoCAD's success has been attributed to its famous open architecture — the flexibility that the end user has to customize the program by using source code files in plain text (ASCII) format — and programming languages (such as AutoLISP, VB.NET, C#, and C++).
As a result, AutoCAD is an extremely flexible drafting program, applicable to all fields. AutoCAD's support for languages other than English, including those using other alphabets, is unparalleled, making AutoCAD highly popular abroad. As a result, AutoCAD is used in all disciplines and in more than 150 countries.
Through a high level of technical innovation and expertise, Autodesk has created a program with advanced features and capabilities, including 3D surface and solid modeling and visualization, access to external databases, intelligent dimensioning, importing and exporting of other file formats, Internet support, and much more.
The major disciplines that use AutoCAD are:
Architectural, Engineering, and Construction (AEC)
Geographic Information Systems (GIS)
Surveying and Civil Engineering
However, AutoCAD has many other lesser-known uses, such as pattern making in the garment industry, sign making, and so on. In this book, I provide examples from several fields. The world of AutoCAD is very broad, and you can learn from seeing the many approaches that AutoCAD makes possible.
Comparing AutoCAD and AutoCAD LT
AutoCAD LT's advantages are its lower cost and its compatibility with AutoCAD. The programming code that is used to create AutoCAD LT is a subset of the code used in AutoCAD. Here are the major differences between AutoCAD and AutoCAD LT:
AutoCAD includes features that enable CAD managers to hold drawings to certain standards, such as for layer names and text styles. AutoCAD LT doesn't contain these features.
AutoCAD LT is not as customizable as AutoCAD, which is both programmable and fully customizable. It also doesn't include the Action Recorder.
AutoCAD LT includes minimal options for 3D; AutoCAD includes a full-featured 3D capability.
AutoCAD LT has fewer presentation features than AutoCAD, which includes visual styles and 3D rendering.
AutoCAD LT is deployable on a network but does not have AutoCAD's network license management feature that includes reporting and flexible licensing.
AutoCAD LT does not offer the database connectivity feature, but you can use tables to connect to data in a Microsoft Office Excel file; AutoCAD offers the flexibility to connect to other types of databases, create labels from the data, and so on.
AutoCAD LT does not come with Express Tools, a set of additional routines that ship with AutoCAD.
AutoCAD LT does not include parametric constraints, which allow you to constrain the relationships among objects, but you can use the parametric constraints that are in a drawing that was created with AutoCAD.
Sheet sets, after being in AutoCAD for a long time, have now made their way into AutoCAD LT 2012.
AutoCAD and AutoCAD LT have a few other minor differences, as well. Some of these differences are only in the user interface, so you can accomplish the same task but the procedure is slightly different.
Starting AutoCAD and AutoCAD LT
This section starts a quick tour of AutoCAD and AutoCAD LT. The first step is to start the program.
On the DVD
The DVD contains a 30-day trial version of AutoCAD 2012 and AutoCAD LT 2012.
This book covers AutoCAD 2012 and AutoCAD LT 2012 running on Windows XP Home/Professional, Windows Vista, or Windows 7. (The figures were taken in Windows 7.) Every computer is set up somewhat differently, so you may need to adjust the following steps slightly. If you didn't install the software yourself and are unfamiliar with the folders (also called directories) on your computer, get help from someone who is familiar with your computer system.
AutoCAD is now available for the Mac OS; this book doesn't cover it, but you can find out more and get a free trial from the Autodesk website. Go to www.autodesk.com/autocadformac to learn more.
If you need information on installing AutoCAD or AutoCAD LT, see Appendix A. Appendix A also covers configuring the software and printers or plotters.
By default, installing AutoCAD or AutoCAD LT places a shortcut on your desktop. You can double-click one of the shortcuts to launch the program that is installed on your machine, or use the Windows Start menu to choose one of the following: For AutoCAD. Start(All) Programs → Autodesk → AutoCAD 2012 – English → AutoCAD 2012 – English (or as appropriate for your language) For AutoCAD LT. Start → (All) Programs → Autodesk → AutoCAD LT 2012 – English → AutoCAD LT 2012 – English (or as appropriate for your language)
When you first open AutoCAD or AutoCAD LT, the Autodesk Exchange window appears, providing access to the Help feature, related applications for purchase, training, tips, and more. To close the window, click its Close button. If you don't want to see this window when you open AutoCAD, uncheck the Show This Window at Start Up check box at the lower-left corner of the window. To display the Autodesk Exchange window at any time, click the Exchange button on the right side of the title bar (see Figure 1.1).
Creating a New Drawing
After you launch AutoCAD or AutoCAD LT, it automatically opens a new drawing named Drawing1. dwg. You can see the drawing name on the title bar. You can start drawing immediately. In Chapter 2, I explain how to start a drawing based on a template and how to open an existing drawing.
STEPS: Starting AutoCAD or AutoCAD LT
1. Click Start on the Windows task bar at the bottom of your screen.
2. Choose one of the following:
For AutoCAD. Start → (All) Programs → Autodesk → AutoCAD 2012 – English → AutoCAD 2012 – English
For AutoCAD LT. Start → (All) Programs → Autodesk → AutoCAD LT 2012 – English → AutoCAD LT 2012 – English
You see a blank drawing named Drawing1.dwg.
If you are continuing with this chapter, keep this drawing open. I cover exiting from AutoCAD and AutoCAD LT later in this chapter.
Using the AutoCAD and AutoCAD LT Interface
AutoCAD offers four quite different preset workspaces, depending on how you want to work. For example, these workspaces determine the Ribbon components, toolbars, and other interface items that you see. AutoCAD offers both 2D and 3D environments. AutoCAD LT has only 2D environments, and the 2D environments for AutoCAD and AutoCAD LT are similar. In this section, I discuss the 2D environment. Both AutoCAD and AutoCAD LT offer two 2D workspaces: Drafting & Annotation and AutoCAD (or AutoCAD LT) Classic. The Drafting & Annotation workspace is the default workspace and displays the Ribbon for executing commands. The AutoCAD Classic and AutoCAD LT Classic workspaces display toolbars and a menu instead.
Note AutoCAD's 3D Modeling and 3D Basics workspaces create a 3D environment along with the 3D drawing templates acad3D.dwt and acadiso3D.dwt. (I cover templates in Chapter 2.) I cover this 3D environment in Part IV, "Drawing in Three Dimensions."
Figure 1.1 shows the default screen that appears when you first open AutoCAD or AutoCAD LT. Your screen may look somewhat different — remember that AutoCAD and AutoCAD LT can be customized in many ways — but the general features will be the same. If you see other items open on your screen, you can close all these items by clicking their Close (X) button.
By default, you see a grid when you open AutoCAD. I explain how to turn off the grid in Chapter 4. The default screen color is dark gray. You can leave it that way or change the drawing area color, as I explain in Appendix A. I use a white background for the figures in this book for clarity.
If you find yourself in a 3D environment in AutoCAD, you'll see a gray background and a perspective view. To work in 2D in AutoCAD, switch to a 2D environment, following these steps in AutoCAD:
1. From the Workspace drop-down list, choose Drafting & Annotation. This displays the Ribbon with 2D commands. 2. Choose Application ButtonNew. From the Select Template dialog box, choose acad.dwt and click Open. This places you in a 2D view.
The AutoCAD and AutoCAD LT screens consist of four important areas. These are discussed in the following sections.
Exploring the drawing area
The blank area in the middle of the screen, called the graphics window or drawing area, is where you draw. You can think of this as a sheet of drafting paper, except that this piece of paper can be any size — even the size of a huge factory or an entire county!
By default, you draw in model space, so called because that's where you draw your models. When you create a new drawing, by default, you are in model space, so you can just start drawing. You can lay out your drawings for plotting in paper space, also called a layout. To switch from model space to a layout, you use the Layout tab at the bottom of the drawing area. You click the Model tab to switch back to model space. (See Chapter 17 for details.)
Rather than the model and layout tabs, you may see Model and Layout1 buttons on the status bar. You can switch between the buttons and tabs by right-clicking either feature and choosing from the shortcut menu.
When you start to draw, you need to specify where to start drawing. One way is to use coordinates. To specify a coordinate, the universally accepted convention is to put the X coordinate first, followed by a comma, and then the Y coordinate. Examples are -3, 5, 3, 2, 6, -2, and -1, -1. These coordinates specify points in the drawing area. You can see the current coordinates of the cursor displayed at the lower-left corner of the AutoCAD window.
Chapter 4 explains how to specify coordinates. To create three-dimensional models, you need to add a Z coordinate when specifying a point. Chapter 21 discusses three-dimensional coordinates.
If you want the maximum amount of free space for drawing, click the Clean Screen button at the right side of the status bar to remove the Ribbon. Click the same button to get it back. You can also press Ctrl+0 to toggle between the two displays. You can double-click the active tab to cycle through three display states of the Ribbon that collapse and expand the Ribbon.
The UCS icon Notice the symbol with two perpendicular lines and X and Y labels in the drawing area in Figure 1.1. This symbol is called the User Coordinate System (UCS) icon. The lines point to the positive directions of the X and Y axes to help you keep your bearings. (In a 3D environment, you see a Z axis as well.) You can change the look of this icon, and turn it on and off, as I explain in Chapter 8. The crosshairs In the drawing area of Figure 1.1, notice the intersecting lines with a small box at their intersection. The small box is called the pickbox because it helps you to select, or pick, objects. The lines are called crosshairs. They show you the location of the mouse cursor in relation to other objects in your drawing. The ViewCube and Navigation Bar On the right side of the drawing area, semi-faded, you see two navigational tools, the ViewCube and the Navigation Bar (or NavBar). The ViewCube is not available in AutoCAD LT. These are mostly used for 3D navigation, which I cover in Chapter 22. You can use the NavBar to zoom and pan in 2D; see Chapter 8 for more information.
Exploring the Ribbon and Quick Access Toolbar
At the top of the application window is the title bar, and directly beneath the title bar is the Ribbon. On the left side of the title bar is the Quick Access Toolbar. The Ribbon has tabs, and each tab is divided into control panels (usually called just panels), which are sections of related commands. I explain how to work with the Ribbon and the Quick Access Toolbar in Chapter 3.
The AutoCAD Classic and AutoCAD LT Classic workspaces do not show the Ribbon; instead, you see toolbars, which are usually docked along the left, top, and right sides of the screen. From the Workspace drop-down list (just to the left of the Quick Access Toolbar), try switching between the Drafting & Annotation workspace and the AutoCAD or AutoCAD LT Classic workspace to see which one you prefer. In Appendix A, I explain how to customize workspaces.
On the Home tab, in the Draw panel of the Ribbon, hover the cursor over the leftmost button. You see a tooltip that says Line, as shown in Figure 1.2. Below the tooltip, a description tells you that this button creates straight-line segments. If you continue to hover the cursor over the Line button, the tooltip expands to provide more information about the command. You use buttons on the Ribbon to execute commands. For example, to draw a line, you click the Line button on the Draw panel of the Ribbon's Home tab. You get some practice drawing lines in the exercise that follows. (In the AutoCAD Classic or AutoCAD LT Classic workspace, you would click the Line button on the Draw toolbar to draw a line.)
If you inadvertently start a command that you don't want to use, press Esc. n
The Quick Access Toolbar contains a few often-used commands that are useful to have available all the time. Examples are commands to start a new drawing, open an existing drawing, and save a drawing. Because you can customize the Ribbon and the Quick Access Toolbar to suit your needs, your screen may appear somewhat different. (See Chapter 29 for information on customizing the Quick Access Toolbar, and see Chapter 33 for information on customizing the Ribbon.) Remember that if the current workspace is AutoCAD Classic or AutoCAD LT Classic, you won't see the Ribbon or Quick Access Toolbar; instead, you'll see a menu bar at the top and several toolbars.