STEPS: Obtaining Drawing Information

1.Open ab12-a.dwg from the CD-ROM.

2.Skip to Step 3 if you are using AutoCAD LT. Choose Tools Inquiry Status. Look at the listing to see how many objects it contains. Check the limits of the drawing. Look at the grid spacing. Read through any other items that interest you.

3.Choose Tools Inquiry Set Variable, or type SETVAR at the command line if you are using AutoCAD LT. At the Enter variable name or [?]: prompt, type ? . At the Enter variable(s) to list <*>: prompt, press Enter to accept the default. Look for the BLIPMODE setting. Check the location of the drawing (DWGPREFIX). Look for the global linetype scale (LTSCALE). Press Enter until you see the Command: prompt again.

4.Press Enter to start the SETVAR command again. At the Enter variable name or [?]: prompt, type ltscale . Type 50 to change the linetype scale. Type regen . The noncontinuous linetypes should now show up more clearly.

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 during which you have worked on the drawing. 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 explains the information that you see when you list an object.

296 Part II Drawing in Two Dimensions

The Layers and Properties toolbars make it easy to tell an object’s layer, linetype, and color. Remember that 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. To access this 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 of 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.

STEPS: 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 that shows several plots of land, as shown in Figure 12-5. OSNAP should be on. Set a running object snap for the endpoint.

1

4

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

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.

298 Part II Drawing in Two Dimensions

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 of 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 it does not include that last imaginary line when calculating the length.

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.

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.

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

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.

300 Part II Drawing in Two Dimensions

STEPS: 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 the endpoint.

1 2 5

4 3

6 7

8

9

Figure 12-9: The AREA command can calculate the area of parcels

D and E.

3.Choose Tools Inquiry Area.

4.At the Specify first corner point or [Object/Add/Subtract]: prompt, right-click 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 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

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.