8.2 The Most Useful of the Most Overlooked - AutoCAD s Inquiry Commands


8.2 The Most Useful of the Most Overlooked “ AutoCAD's Inquiry Commands

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).

8.2.1 Tell Me About It “ The List Command

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.

Do This: 8.2.1.1 Listing an Object's Properties

  1. 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:

  2. 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.

     
    start figure
     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 
    end figure

    Figure 8.2.1.1.2a:
       

    Here we see:

    • the type of object ( Line )

    • its layer ( Fred )

    • that it was drawn in Model Space

    • its Handle (for programmers)

    • its beginning and ending point, length, and angle

     

    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.

     
    start figure
     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 
    end figure

    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:

    • the lwpolyline is Closed

    • its width

    • the beginning and ending points of each segment

    • the area and perimeter of the lwpolyline

    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.

8.2.2 How Long or How Far “ The Dist Command

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?

Do This: 8.2.2.1 Determining Distance

  1. If you're not still in samples.dwg , please open it now. It's in the C:\Steps\Lesson08 folder.

  2. 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).

     


    Figure 8.2.2.1.2a:

     

    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.)

     
    start figure
     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 
    end figure

    Figure 8.2.2.1.3a:
       

    Here, AutoCAD shows:

    • the true distance

    • the 2-dimensional angle in the XY plane

    • the 3-dimensional angle from the XY plane

    • the distance along the X-plane (shown as Delta X )

    • the distance along the Y-plane (shown as Delta Y )

    • the distance along the 3-dimensional Z-plane (shown as Delta Z )

Aren't these cool commands?! But wait “ the best is yet to come!

8.2.3 Calculating the Area

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.

Do This: 8.2.3.1 Calculating Area

  1. If you're not still in samples.dwg , please open it now. It's in the C:\Steps\Lesson08 folder.

  2. 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).

     


    Figure 8.2.3.1.3a:

     

    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!

8.2.4 Identifying Any Point with ID

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.

Do This: 8.2.4.1 Identifying Coordinates in a Drawing

  1. If you're not still in samples.dwg , please open it now. It's in the C:\Steps\Lesson08 folder.

  2. 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.




AutoCAD 2004. One Step at a Time (Part 1)
AutoCAD 2004. One Step at a Time (Part 1)
ISBN: N/A
EAN: N/A
Year: 2003
Pages: 162

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