AutoCAD provides four commands “ List , Dist , Area , and ID “ whose simplicity has led to their being almost completely forgotten. We'll cover them quickly because they are so simple; but I do recommend them as possible residents of monitor stick'ems (those tiny bits of paper taped to the side of your monitor with cheater notes).
One of the problems you may run into on occasion is a modifying command not working exactly as you might expect. The object you're modifying not being what you think it's frequently causes this. For example, you may try to edit a polyline arc only to receive a message from AutoCAD that the object isn't a polyline; or you may freeze a layer only to discover that something you thought was on that layer doesn't freeze. When something unexpected like this happens, do a List on the object to see if you can spot the problem. Look at some examples.
Note | In addition to the command line and toolbar, you can find all the Inquiry commands listed in the Inquiry section of the Tools pull-down menu. |
Open the samples.dwg file from the C:\Steps\Lesson08 folder. The drawing looks like Figure 8.2.1.1a.
Figure 8.2.1.1a:
Follow these steps.
Tools | Command Sequence | Steps | ||
---|---|---|---|---|
List Button | Command: ls | 1. Enter the List command by typing list or ls at the command prompt. Alternately, you can use the List button on the Inquiry toolbar. | ||
Select objects: Select objects: [enter] | 2. Select the upper red line, and then hit enter to confirm that you've finished selecting. AutoCAD switches to the text screen and displays the information in Figure 8.2.1.1.2a. | |||
LINE Layer: "FRED" Space: Model space Handle = 26 from point, X= 2.5424 Y= 7.7686 Z= 0.0000 to Point, X= 7.7140 Y= 7.7686 Z= 0.0000 Length = 4.8717, Angle in XY Plane = 0 Delta X = 4.8717, Delta Y = 0.0000, Delta Z = 0.0000 Figure 8.2.1.1.2a: | ||||
Here we see:
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| 3. Return to the graphics screen either by hitting the F2 key or by picking on the X in the upper right corner of the text screen. | |||
| Command: [enter] | 4. Let's repeat the procedure with another object. | ||
Select objects: Select objects: [enter] | 5. Select the dashed rectangle, and then hit enter. AutoCAD again switches to the text screen and displays the information in Figure 8.2.1.1.5a. | |||
LWPOLYLINE Layer: "0" Space: Model space Color: 6 (magenta) Linetype: "HIDDEN" Handle = 28 Closed Constant width 0.0625 area 3.5494 perimeter 7.6074 at point X= 5.9830 Y= 7.2213 Z= 0.0000 at point X= 8.1448 Y= 7.2213 Z= 0.0000 at point X= 8.1448 Y= 5.5794 Z= 0.0000 at point X= 5.9830 Y= 5.5794 Z= 0.0000 Figure 8.2.1.1.5a: | ||||
Again, we see the type of object and layer. But since this object is a multi-segmented lwpolyline, we also see that:
Note that the linetype and color characteristics of this object were not assigned by layer. These characteristics were assigned using the Color and Linetype methods . As a result, the List command also shows Color and Linetype . It'll show these only when they aren't defined by layer. | ||||
| Command: [enter] | 6. Repeat the List command for the rest of the objects in this drawing. (It's best to list objects one at a time.) Notice that List provides slightly different information for each. |
Another useful tool helps determine just what its name implies “ distance . How long is a line or how far is it from here to there?
If you're not still in samples.dwg , please open it now. It's in the C:\Steps\Lesson08 folder.
Follow these steps.
Tools | Command Sequence | Steps | ||
---|---|---|---|---|
Distance Button | Command: di | 1. Enter the Dist command by typing dist or di at the command prompt. Alternately, you can pick the Distance button on the Inquiry toolbar. | ||
Specify first point: _endp of Specify second point: _cen of | 2. Using OSNAPs, pick the endpoint of the cyan line. Then pick the center of the lower blue circle (see Figure 8.2.2.1.2a). | |||
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| 3. AutoCAD returns the information in Figure 8.2.2.1.3a on the command line. If you can't see all of the information, toggle to the text screen with the F2 key. (Close the text screen when you've finished.) | |||
Distance = 2.0267, Angle in XY Plane = 319, Angle from XY Plane = 0 Delta X = 1.5216, Delta Y = -1.3388, Delta Z = 0.0000 Figure 8.2.2.1.3a: | ||||
Here, AutoCAD shows:
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Aren't these cool commands?! But wait “ the best is yet to come!
The List command provides the area of closed rectangles, polygons, and circles as you saw in Section 8.2.1. But the boundaries in which we need to determine area aren't always closed objects. Sometimes, we need an area bounded by simple lines or even multiple objects. For this reason, AutoCAD provides the Area command.
The Area command sequence is
Command: area (or aa )
Specify first corner point or [Object/Add/ Subtract]: [select the first corner of the area's boundary]
Specify next corner point or press ENTER for total: [continue selecting corners “ this prompt repeats until you hit enter]
Area = 3.5494, Perimeter = 7.6074
The options are fairly clear.
The Specify first corner point option is the default and simply instructs you to select the first point on the boundary of the area to be calculated. AutoCAD follows with Specify next corner point prompts until the boundary is defined and you hit enter to complete the command. AutoCAD then show the Area within and Perimeter around the boundary. (Note: You must identify at least three points to define an area. If you don't "close" the area, AutoCAD will assume a line between the last point selected and the first point selected and calculate the area accordingly .)
The Object option allows you to select an object “ a circle, polygon, and so forth “ and defines the boundary from the edges of the object.
Add and Subtract are ways to keep a running total of several areas or to get the area of a bounded site minus a smaller site “ such as the area of a plot of land minus the house sitting on it.
If you're not still in samples.dwg , please open it now. It's in the C:\Steps\Lesson08 folder.
Follow these steps.
Tools | Command Sequence | Steps |
---|---|---|
Area Button | Command: aa | 1. Enter the Area command by typing area or aa at the command prompt. Alternately, you can pick the Area button on the Inquiry toolbar. |
| Specify first corner point or [Object/Add/ Subtract]: o | 2. Tell AutoCAD you want to use the Object option. |
Select objects: | 3. Select the circle in the center of the polygon (Figure 8.2.3.1.3a). | |
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Area = 3.1416, Circumference = 6.2832 | AutoCAD returns this information on the command line. | |
| Command: [enter] | 4. Repeat the command. |
Specify next corner point or press ENTER for total: Specify next corner point or press ENTER for total: [enter] | 5. Select the five points on the polygon (use OSNAPs). | |
Area = 9.5106, Perimeter = 11.7557 | AutoCAD returns this information on the command line. | |
| Command: [enter] | 6. Repeat the command. |
| Specify first corner point or [Object/Add/ Subtract]: a | 7. Tell AutoCAD you want to use the Add option. |
Specify first corner point or [Object/ Subtract]: Specify next corner point or press ENTER for total (ADD mode): | 8. AutoCAD prompts again for points or objects. Pick the five points of the polygon as you did in Step 5. | |
Specify next corner point or press ENTER for total (ADD mode): [enter] | 9. After selecting the fifth point, hit enter to complete the polygon. | |
Area = 9.5106, Perimeter = 11.7557 Total area = 9.5106 | AutoCAD tells you what the Area and Perimeter are so far, and the Total area defined during this command. It then prompts again as it did previously. | |
| Specify first corner point or [Object/ Subtract]: o | 10. Select the Object option. |
(ADD mode) Select objects: | 11. Select the upper blue circle. | |
Area = 2.9741, Circumference = 6.1134 Total area = 12.4846 | AutoCAD tells you the Area and Circumference of the circle, and then adds the area of the circle to the Total Area . Then it prompts again. | |
(ADD mode) Select objects: | 12. Hit enter to leave the Add mode . | |
Specify first corner point or [Object/ Subtract]: [enter] | 13. AutoCAD returns you to the initial prompt. Hit enter to exit the command. | |
| Command: [enter] | 14. Repeat the Area command. |
Specify first corner point or [Object/Add/ Subtract]: a | 15. Tell AutoCAD you want to use the Add option. We'll start by adding the outer boundary of the polygon; then we'll subtract the inner circle. | |
Specify first corner point or [Object/ Subtract]: | 16. AutoCAD prompts again for points or objects. Pick the five points of the polygon as you did previously. | |
Specify next corner point or press ENTER for total (ADD mode): [enter] Area = 9.5106, Perimeter = 11.7557 Total area = 9.5106 | 17. After selecting the fifth point, hit enter to complete the polygon. | |
| Specify first corner point or [Object/ Subtract]: s | 18. Now tell AutoCAD you want to Subtract . |
Specify first corner point or [Object/Add]: o | 19. We want to subtract an Object . | |
(SUBTRACT mode) Select objects: | 20. Select the circle inside the polygon. | |
Area = 3.1416, Circumference = 6.2832 Total area = 6.3690 | AutoCAD tells you the Area and Circumference of the circle, and then subtracts the area from the Total Area . This is the Total area of the polygon less the area of the circle. | |
(SUBTRACT mode) Select objects: [enter] Specify first corner point or [Object/Add]: [enter] | 21. Hit enter twice to leave the command. |
Note | The Area command will only work on points or objects selected in a single, 2-dimensional plane. We'll use other tools when we get to Z-Space! |
The last of these simple tools enables you to identify any point in a drawing. This can prove particularly beneficial to the drafter who works in true coordinates (see the insert in Section 1.8) for an explanation of true coordinates) or someone working with the Ordinate system. We'll discuss the Ordinate system in Lesson 14.
The command sequence for ID is
Command: id
Specify point: [select a point in the drawing]
X = 0.0000 Y = 0.0000 Z = 0.0000
As you can see, AutoCAD responds with the S,Y,Z coordinate location of the selected point.
If you're not still in samples.dwg , please open it now. It's in the C:\Steps\Lesson08 folder.
Follow these steps.
Tools | Command Sequence | Steps |
---|---|---|
Locate Point Button | Command: id | 1. Enter the ID command. Alternately, you can pick the Locate Point button on the Inquiry toolbar. |
| Command: id Specify point: _cen of | 2. Select the center point of the upper blue circle. |
X = 3.5472 Y = 6.3395 Z = 0.0000 | AutoCAD returns the coordinates locating the center of the circle. | |
Command: qsave | 3. Exit the drawing. Don't save your changes. |