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5.Choose Tools Inquiry Time. Check the current time against your watch. (The command takes the time from your computer’s clock.) Look at the total editing time to see the total time the drawing has been worked on. Press Enter to end the command.

6.Do not save this drawing. Leave the drawing open if you’re going on to the next exercise.

Object-Level Information

Several commands exist solely to provide information about the objects in your drawing.

Listing objects

The LIST command displays information about selected objects. The information displayed depends on the object. For example, the LIST command gives you the radius of a circle and the length of a line.

To list an object, choose Tools Inquiry List. Figure 12-4 shows a typical listing for a line.

Figure 12-4: A typical listing for a horizontal line.

Table 12-2 shows the meaning of the information you receive when you list an object.

	Table 12-2: LIST Command Information
Data	Comments
Layer	Lists the object’s layer. If the color and linetype are not ByLayer or ByBlock,
	AutoCAD lists these as well.
Space	Tells you if the object is in model space or paper space. (Chapter 17 covers paper
	space.)
Handle	Every object in your drawing has a handle. Your drawing’s internal database uses
	handles to keep track of objects.
From point	Because the example in Figure 12-4 lists a line, it shows the start point.
To point	The endpoint of the line.
Length	The line’s length.
Angle in XY Plane	The line’s angle. This line is horizontal, so its angle is zero.
Delta X	The change in the X coordinate from the start point to the endpoint.
Delta Y	The change in the Y coordinate from the start point to the endpoint.

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The Layers and Properties toolbars make it easy to tell an object’s layer, linetype, and color. Remember, when you select an object, its layer, linetype, lineweight, color, and plot style appear in these toolbars. Most of this information is also available from the Properties palette — choose Properties from the Standard toolbar.

Calculating distances

You can easily calculate the distance between any two points by using the DIST command. Choose Tools Inquiry Distance. The command prompts you for two points. You can use any means of specifying a point, although object snaps or snap mode are useful if you want to be sure which point you’re specifying. Here is a typical display for a vertical line:

Distance = 19’-0”, Angle in XY Plane = 270, Angle from XY Plane = 0 Delta X = 0’-0”, Delta Y = -19’-0”, Delta Z = 0’-0”

You can use this information to check dimensions (covered in Chapter 14) or to make calculations that you need for drawing.

Finding coordinates

Finding a coordinate is even easier than calculating a distance. Choose Tools Inquiry ID Point (or just type id ). The ID command prompts you for a point. You can use any means of specifying a point, although object snaps or snap mode are useful. Here is a typical listing:

X = 61’-5 1/8” Y = 32’-4 5/8” Z = 0’-0”

You can use this information to find an absolute coordinate.

On the	The drawing used in the following Step-by-Step exercise on obtaining object information,
CD-ROM	ab12-a.dwg, is in the Drawings folder on the CD-ROM.

STEP-BY-STEP: Obtaining Object Information

1.Open ab12-a.dwg from the CD-ROM if it isn’t already open from the previous exercise. This is a civil engineering drawing showing several plots of land, as shown in Figure 12-5. OSNAP should be on. Set a running object snap for the endpoint.

2

3

1

4

Figure 12-5: A civil engineering drawing of several plots of land.

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2.Choose Tools Inquiry List. At the Select objects: prompt, pick 1 in Figure 12-5. Press Enter to end object selection. The result is shown in Figure 12-6. Note the surveyor’s units.

Figure 12-6: The result of using the LIST command on an arc.

3.Choose Tools Inquiry Distance. At the Specify first point: prompt, choose the endpoint at 2 in Figure 12-5, using the endpoint running object snap. At the Specify second point: prompt, choose the endpoint at 3. Here’s the result:

Distance = 2740.90, Angle in XY Plane = N 89d23’34” E, Angle from XY Plane = E

Delta X = 2740.75, Delta Y = 29.05, Delta Z = 0.00

4.Choose Tools Inquiry ID Point. At the Specify point: prompt, pick the endpoint at 4 in Figure 12-5. Here is the result:

X = 6065.67 Y = 3450.58 Z = 0.00

5.Do not save this drawing. Leave the drawing open if you’re going on to the next exercise.

Caution	The precision set in the Units dialog box (Format Units) affects the results of the LIST, DIST,
	and ID commands. See Chapter 5 for more information on the Units dialog box.

Calculating area and perimeter

You can also calculate the area and perimeter of any area. To start the AREA command, choose Tools Inquiry Area.

You can specify points bounding the area that you want to calculate. The points don’t have to be on an object. The command calculates the area and perimeter as if you had drawn lines between all the points. The command automatically closes the area if you don’t close the area by assuming that the last point is the same as the first point. This option is limited to areas with straight sides.

Instead of picking points, you can use the Object option to calculate the area of objects, which gives you the flexibility to use areas that include curves. Acceptable objects are circles, ellipses, splines, polylines, polygons, regions, and objects created with the 2D SOLID command. (Chapter 16 covers splines, polylines, regions, and solids.) This option calculates an area but adds a length instead of a perimeter. For a circle, you get a circumference. Although a polyline may have the exact same shape as an arc, you cannot calculate the area of an arc. Polylines and splines can be open. In this case the area is calculated as if you had drawn a line from the endpoint to the start point but does not include that last imaginary line when calculating the length.

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To calculate the area of irregular shapes, you can keep a running total by using the Add option. Start by specifying the first area. Then use the Add option and specify a second area. The result is the sum of the two areas. You can continue to add areas. You can also use the Subtract option to subtract areas.

Figure 12-7 shows an example of calculating the open area in an office floor plan by picking points. The point objects show the points that were used to calculate the area and perimeter.

Figure 12-7: Calculating the area and perimeter for an office floor plan.

You can also use the BOUNDARY command to create one polyline or region from a complex area. (Chapter 16 covers boundaries and polylines.) You can then use the Object option of the AREA command instead of picking points. However, notice that BOUNDARY included the open doors in the area selected for the office floor plan, as shown in Figure 12-8.

On the	The drawing used in the following Step-by-Step exercise on using the AREA command,
CD-ROM	ab12-a.dwg, is in the Drawings folder on the CD-ROM.

STEP-BY-STEP: Using the AREA Command

1.Open ab12-a.dwg from the CD-ROM if it isn’t already open from the previous exercise.

2.Use ZOOM Window to zoom in on the parcels of land labeled D and E, as shown in Figure 12-9. OSNAP should be on with a running object snap for endpoint.

3.Choose Tools Inquiry Area.

4.At the Specify first corner point or [Object/Add/Subtract]: prompt, rightclick and choose Add to start Add mode. At the Specify first corner point or [Object/Subtract]: prompt, pick 1 in Figure 12-9 by using the Endpoint running

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object snap. At the Specify next corner point or press ENTER for total (ADD mode): prompt, continue to pick 2, 3, 4, and 5. Press Enter. The command line lists the area and perimeter. (Your figures may be different if you picked different points.)

Area = 123575.16, Perimeter = 1480.17

Total area = 123575.16

Figure 12-8: Using the BOUNDARY command to create an object for use with the AREA command. The boundary is indicated with a dashed line.

1 2 5

4 3

6 7

8

9

Figure 12-9: The AREA command can calculate the area of parcels D and E.

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5.At the Specify first corner point or [Object/Subtract]: prompt, pick 6 in Figure 12-9. At the Specify next corner point or press ENTER for total (ADD mode): prompt, pick 7, 8, and 9. Press Enter to complete point selection. The command line reports the area and perimeter of the second area and adds the two areas together to give you the total area. Press Enter again to end the command.

Area = 183399.88, Perimeter = 1884.62 Total area = 306975.04

6.Do not save the drawing. Keep it open if you’re continuing to the next exercise.

Note	The MASSPROP command is mostly used for 3D drawings, but it can also be used on regions,
	which are 2D solid surfaces, such as a shape cut from sheet metal. This command provides
	area and perimeter but also other engineering calculations, such as centroids, moments of
	inertia, the product of inertia, and so on. Chapter 24 covers this command further.

Getting information from the Properties palette

You can also get information about an object by selecting it and choosing Properties from the Standard toolbar. I discuss this Properties palette in Chapter 11 for changing layer, color, linetype, and lineweight properties. As you can see in Figure 12-10, the window also lists the line’s start and end points; delta (change) in X, Y, and Z; length; and angle — much like the LIST command. However, you can change the start and end points directly in this window.

Figure 12-10: The Properties palette lists information about a selected object.

On the	The CD-ROM contains two routines that provide information about your objects. Linesum
CD-ROM	provides the total length of selected lines. Polydis provides the length of a selected poly-
	line. Look in the Software\Chap12 folder.