Michael’s Corner

Michael's Corner is a monthly publication written by Michael E. Beall, Autodesk Authorized Author and peripatetic AutoCAD trainer. Michael travels all over the USA, bringing his fantastic experience and great understanding of AutoCAD to his clients. Michael's Corner brings together many of the tips, tricks and methods developed during these training sessions for the benefit of all users.

Michael's Corner provides something for every AutoCAD user. Every month, a number of articles cover a wide range of topics, suitable for users at all levels, including "The Basics" for those just starting out. Essentially, the aim of Michael's Corner is to help all AutoCAD users work smarter and faster.

This month…

From the Vault

Originally published August 2005

More Fields in A2005 & A2006

You will really love this one. Wouldn't it be cool to have the area of a closed polyline update when the polyline itself changed? One method of changing the shape of a polyline is the Stretch command. When you have a field associated with the area of the selected object, when that object changes, you just update the field.

In the following example I traced the perimeter of a room with a polyline on a separate layer.

Instructions to Automatically Update the Area of a Closed Polyline

1. After creating a closed polyline, launch the Field command (InsertField).
2. From the list of Field names, select Object, then click the Select Objects button and select the closed polyline.
3. The Field dialog box will re-open with a number of properties related to the selected object. The Area property is at the top of the list.
4. Select a Format and a Precision from the lists on the right, then click OK.
5. The Mtext indicating the area of the selected polyline is attached to the cursor. If you can't see the text, enter H for the Height option and enter the necessary value so you can see the text.
6. Specify a location for the field.

7. Launch the Stretch command and change the shape of the polyline. In this exercise, I have increased the size of the area where a column or mechanical chase may be located in the upper left corner of the room.
8. To update the field, regenerate the drawing.

Note: The variable Fieldeval specifies when a field is to be updated. (See ExpressToolsSystem Variable Editor) The default value of 31 specifies that a field is to be updated when its associated information is modified.

To give credit where due, I found this trick on Shaan Hurley's website, http://autodesk.blogs.com/between_the_lines. His site has lots of links and AutoCAD tips and he's pretty diligent about updating his site several times per week.

For those of you doing civil engineering…
or creating golf courses in your spare time…
that field trick is a great way to keep track of the square footage of the area of a closed spline during the design phase of your project!

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