Bug Watch: February 2003

31 Jan, 2003 By: Steve Johnson

Attribute angle affliction (2002 SP1)

Create a block with one or more attributes. Insert the block at various rotation angles. Now select the block insertions. Using the Properties window, increase the scale of the block insertions by a substantial amount, say 100 times. You will need to change the Scale x, Scale y, and Scale z values in turn. This should scale all of the block insertions about their insertion points, which is a useful thing to be able to do. But hang on, what's this? The attributes are all skewed. In fact, if you list the blocks, you discover that the attributes now have an obliquing angle equal to their rotation angle.

Workaround. You can find dozens of free AutoLISP routines on the Web for scaling blocks about their insertion points. Use one of those routines instead of the Properties window. [Eds. note: The Cadalyst code coffers feature several such routines-for example, Scale Multiple Blocks from July 2001 You can also search the code archives for something suitable.]

Name shame (2002 SP1)

Open a drawing called Louise. Now save it to the desktop under a different name. Use the Saveas command and change its name to Emma. Now pick the Desktop icon from the places list on the left of the Saveas dialog box (you may need to scroll down to see Desktop displayed). The filename appears as Emma in the edit box. If you pick the Save button, the job is done, right? Wrong. Take a look at your desktop. You won't find emma.dwg. Instead, you find louise.dwg. AutoCAD saved the drawing under its original name, rather than the name you specified.

This bug also occurs if you navigate to the Desktop using the Look In popup list.

Workaround. None known, other than navigating to the Desktop before entering the filename.

Lock shock (2002 SP1)

You can draw objects on a specific layer and lock that layer to prevent accidental modification of those objects. The AutoCAD User Guide says, "When a layer is locked, none of the objects on that layer can be modified until you unlock the layer." This obviously applies to operations that directly modify the locked objects, such as erase, move, grip editing, and so on. It should also apply to operations that indirectly modify the locked objects, too. For example, when you have an associative hatch object on a locked layer and you grip-edit some unlocked objects that form part of the hatch boundary, AutoCAD correctly allows modification of the unlocked objects and prevents the locked objects from changing. You are also warned about this at the command prompt:
Associative hatch entity on locked or frozen layer. No update performed.

It's fairly common to place dimensions on a specific layer and to lock that layer after dimensioning is complete. Obviously, it's particularly important that dimensions are not accidentally modified. AutoCAD 2002 introduced the object-associative dimension feature, but somebody forgot about locked layers. Let's say you have objects on unlocked layers. You dimension those objects and then lock the dimension layer. If you modify the unlocked objects, the locked dimensions should remain unmodified. They don't. They change, without even a warning message. Indeed, the only information you get at the command prompt is misleading. Let's say you have a line that is object-associatively dimensioned, and the dimension layer is locked. You use the Stretch command to stretch one end of the line. The interaction looks like this:
Command: Stretch
Select objects to stretch by crossing-window or crossing-polygon...
Select objects: Specify opposite corner: 2 found
1 was on a locked layer.

AutoCAD appears to inform you that the layer-locking mechanism applies to this operation, but it's lying. Both the line and the dimension are modified.

Workaround. Avoid object-associative dimensions by setting the DIMASSOC system variable to 1, rather than its default value of 2. AutoCAD's old point-associative dimensions are not afflicted in the same way. If you need to convert dimensions from object-associative to point-associative, you can use the Dimdisassociate command. Here's hoping that AutoCAD 2004 will iron out the various problems that currently make object-associative dimensions more trouble than they are worth.

More News and Resources from Cadalyst Partners

For Mold Designers! Cadalyst has an area of our site focused on technologies and resources specific to the mold design professional. Sponsored by Siemens NX.  Visit the Equipped Mold Designer here!

For Architects! Cadalyst has an area of our site focused on technologies and resources specific to the building design professional. Sponsored by HP.  Visit the Equipped Architect here!