Chapter 11: Edit for Credit 241

The REVERSE command provides an easy way of reversing the direction of lines and polylines. Why does that matter? Well, most of the time it doesn’t, but if you happen to be using a complex linetype that uses text or a directional arrow block, you probably want the text to read right-way-up and the arrow to point in the right direction. Lines, polylines, and other entity types have start points and endpoints, and therefore, a direction that runs from the former to the latter. Instead of redrawing your linework so your text or symbols appear the right way up, use the REVERSE command to flip the start and endpoints.

The new system variable PLINEREVERSEWIDTHS controls how REVERSE handles polylines with varying widths. When set to the default of 0 (zero), REVERSE reverses the start and end sequence but doesn’t affect the width. When set to 1, the start and end widths of segments are also reversed.

The Delete Duplicate Objects tool (also known as the OVERKILL command) looks for fully or partially overlapping objects, and either combines or deletes them. It’s covered in Chapter 10.

When Editing Goes Bad

Analysis of AutoCAD users’ actions suggests that one of the most commonly used commands is Undo. It comes in several forms and depth of action, which we now reveal. If you are the impatient type, you can jump ahead to the last two items because they’ll probably account for the majority of your undo actions.

OOPS: As we discuss in Chapter 10, the OOPS command unerases the last set of erased objects, even if other editing or drawing actions have taken place in between. You need to type this command in because there aren’t menu or Ribbon picks for it.

UNDO: This command is quite versatile and powerful, as controlled by several options. Among other things, you can have it undo a specified number of actions, or you can have it drop a marker flag, or you can have it undo back as far as the marker flag. See the help facility for more information. You need to type this command in because the only menu pick (to be discussed in a moment) undoes only one step and doesn’t prompt for the other options.

U: This command is available in two forms. When typed in as a command, it undoes the last thing you did, and you can use it repeatedly to step back through the current editing session. You can also enter it as a prompt during a number of other commands, such as LINE, PLINE, and COPY. In this case, it undoes the last line or polyline segment, or the last objects to be copied — but then the parent command resumes, and you can continue drawing or placing copies.

www.it-ebooks.info

242 Part II: Let There Be Lines

REDO: This command reverses the last U or UNDO operation and must immediately follow one of them.

DOO-DOO: (Or words to that effect.) This isn’t a command, but instead is what you say when you Undo too many steps and then learn to your horror that REDO can only redo one undo step.

MREDO: This command reverses multiple undos, and pretty much eliminates the need for DOO-DOO. It has several advanced options.

BAK: This isn’t a command; it’s a file type. Whenever you save your work in process, AutoCAD creates a file with the extension .bak that contains how your drawing looked immediately after the previous save. You can go back to this version simply by using Windows Explorer to rename the BAK file to one with the .dwg extension.

SV$: This isn’t a command; it’s a file type. As you work, AutoCAD automatically saves a copy of your drawing every ten minutes and gives it the .sv$ file extension. You can go back to this version simply by using Windows Explorer to rename the SV$ file to one with the .dwg extension. You’ll find your SY$ files in the c:\Users\<login name>\appdata\local\ temp folder, but you can use the Files tab of the OPTIONS command to have them go to any location you like.

Undo button: The Quick Select menu includes an Undo button, just like many Windows applications. It invokes the UNDO 1 command and option.

Redo button: The Quick Select menu includes a Redo button, just like many Windows applications. It invokes the REDO 1 command and option.

Don’t you just wish that the real world had Undo and Redo buttons?

www.it-ebooks.info