- Chapter Objectives
- Introduction
- Creating a New Drawing
- Model Space and Layout Space
- Communicating with AutoCAD
- Object Snaps, Ortho Mode, and Polar Tracking
- Undo/Redo
- Grid and Snap
- Draw a Circle
- Navigating Around the Drawing
- Object Properties
- Layers
- Dimension Styles
- Dimensioning
- Modifying Drawing Objects
- Grip Editing
- Introduction to Advanced Editing Techniques
- Cleaning Up Layout Space
- Plotting and Page Setups
- Chapter Summary
- Chapter Test Questions
This chapter is from the book
This chapter is from the book
This chapter is from the book
Communicating with AutoCAD
When you create a drawing, you are placing AutoCAD objects in the drawing. There are different types of objects (lines, arcs, circles, text, etc.). Each type of object has a unique set of properties. When you create an object, AutoCAD will ask you to specify the various aspects of that object. This is done primarily through prompts for information at both the command line window and the cursor.
objects: Graphical drawing elements, such as lines, arcs, circles, polylines, and text.
The Command Line
The command line window is at the bottom of the drawing area by default (see Figure 2-7). This is one place where AutoCAD communicates with you. When you select a tool, AutoCAD will display the command name in the command line and then prompt you for more information. The command line can be docked at the top or bottom of the drawing window and moved. It can also be turned off completely, but this is not recommended.
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Figure 2-7 The command line window
Dynamic Input
Dynamic input (see Figure 2-8) uses a command prompt that moves with your cursor and provides instant, dynamic feedback as you move around the drawing. Dynamic input provides you with active, heads-up feedback that allows you to read and respond to AutoCAD’s prompts without changing focus away from your drawing. Dynamic input can be turned on and off by toggling the Dynamic Input button on the status bar.
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Figure 2-8 Dynamic input
Whether you use dynamic input, the command line window, or both, the general process you’ll follow when creating drawing objects is this:
1 Start a command.
2 Read AutoCAD’s prompt.
3 Pick points and/or respond to prompts.
4 Press <Enter> or <Esc> to end the command.
Sometimes the AutoCAD prompts can be difficult to decipher. There are some general conventions that AutoCAD uses.
AutoCAD will ask you to specify a placement point (for example, the start point of a line or arc or the center point of a circle). You can specify a placement point by picking a point on the screen, typing in a coordinate, or using an object snap.
When there are multiple ways to create an object, AutoCAD will display a down arrow next to the dynamic input prompt (see Figure 2-8). Press the down arrow key to see the list of command options.
At the command line, options are enclosed in square brackets [ ] and are separated by a space. You specify an option by selecting it with your mouse or by typing in the blue highlighted capital letter(s) shown for that option. For example, when drawing a circle, AutoCAD gives you the following prompt and options:
Specify center point for circle or [3P 2P Ttr (tan tan radius)]:
In this example, AutoCAD is asking you either to specify the center point of the circle or to select one of three options (3P, 2P, or Ttr). To specify the Ttr option, you would either pick it with your mouse or type T and press <Enter>.
Keep in mind that when you specify a point or select an option, AutoCAD will continue to ask you for more information until it has everything it needs to create that object.
EXERCISE 2-4 DRAWING A LINE
1 Select the Model tab to switch to model space.
2 Choose the Line tool from the Draw panel (see Figure 2-9). AutoCAD prompts you to Specify first point:.
Figure 2-9 The Line tool on the Draw panel
3 Look at the command line. AutoCAD shows the following:
LINE Specify first point:
LINE is the command you started when you chose the Line tool. AutoCAD is asking where you want to start the line.
4 Pick anywhere on the screen to start the line. You should now have a rubber-band line extending from the first point you specified along with dynamic information about the length and direction of the rubber-band line (see Figure 2-10).
Figure 2-10 Dynamic display information
rubber band: A live preview of a drawing object as it is being drawn. The rubber-band preview allows you to see objects as they are being created.
5 AutoCAD prompts you to Specify next point or ↓. The down arrow indicates that a command option is available. Press the down arrow key, and you’ll see the Undo option appear (see Figure 2-11).
Figure 2-11 Dynamic display options
6 Look again at the command line. It shows:
LINE Specify next point or [Undo]:
You can now either specify the next point on the line, choose the Undo option from the dynamic display, pick the Undo option from the command line with your mouse, or type U<Enter> to undo that point.
7 Pick another point anywhere on the screen. AutoCAD will draw a single line segment and automatically start drawing another line segment. AutoCAD again prompts you to Specify next point or ↓.
8 Press the down arrow and select Undo from the option list. The second point you specified is “undone,” and the rubber-band line is now extending from the first point you selected.
9 AutoCAD again prompts you to Specify next point or ↓. Pick another point on the screen. AutoCAD draws that line segment and repeats the prompt.
10 Press <Esc> to end the LINE command.
11 Save your drawing.
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The dynamic input at the cursor should disappear, and you should now see the prompt Type a command displayed at the command line. This is AutoCAD’s way of letting you know that it is idle and ready for the next command.