Sunday, September 30, 2007

System Variables I Cannot Live Without - The Top Ten List

System variables have been one of the most important aspects of AutoCAD throughout its history.I wonder how complicated the life would have been without these tiny little masters. Here goes a few of them I cannot live without.
  1. FILEDIA - Suppresses display of the file dialog boxes. This is the culprit behind one of the most commonly asked questions by the newcomers about missing file dialog box.
  2. MIRRTEXT - Controls how the MIRROR command reflects text.Ignorance of this system variable may double your work at times.
  3. PICKFIRST - Controls whether you select objects before (noun-verb selection) or after you issue a command.For the beginners, I would suggest to keep the noun-verb selection off until they become familiar with the normal selection methods.
  4. LTSCALE - Sets the global linetype scale factor.It's required to be setup as per the drawing scale with each new drawing to get proper linetype display.
  5. DIMSCALE - Sets the overall scale factor applied to dimensioning variables that specify sizes, distances, or offsets.As in the case of LTSCALE variable, this is also required to be setup properly at the beginning of each new drawing to get proper dimension display.
  6. SNAPANG - Sets the snap and grid rotation angle for the current viewport relative to the current UCS.I often use this variable to draw something at a certain angle.
  7. EDGEMODE - Controls how the TRIM and EXTEND commands determine cutting and boundary edges.A must know variable for neat TRIM and EXTEND operations.
  8. ATTREQ - Determines whether the INSERT command uses default attribute settings during insertion of blocks.Setting it to 0 will avoid attribute prompts at the time of block insertion.
  9. MODEMACRO - Displays a text string on the status line, such as the name of the current drawing, time/date stamp, or special modes.Very interesting and powerful when DIESEL expressions are used inside.
  10. USERIx/Rx/Sx - Used for storage and retrieval of user-defined integer/real/string values. Very handy variables to store values for macro operations.
As you can see, it was really tough to select only ten out of hundreds of useful ones.Anyway, top ten is always top ten.Your top ten may vary depending upon the way and field of your work (For example 3D guys will have another story to tell you).If you feel that I have left out any inevitable ones, feel free to point it out here.Finally, here is a list of some system variables which could not make it to the top ten list, but still worthy enough to make your life a lot easier.
  • SDI
  • CTAB


Anonymous said...

One sysvar that I recently discovered is -DWGUNITS (note the hyphen) which does not seem to be documented in plain vanilla AutoCAD.

-DWGUNITS is a sysvar that is used in Autodesk vertical applications like Land Desktop Development (LDD).

It basically does for the vertical apps what INSUNITS does in plain vanilla AutoCAD.

If a drawing was created using a vertical app like LDD, however the -DWGUNITS was set takes precedence over how INSUNITS is/was set in plain vanilla AutoCAD. Therefore, no matter what you set your INSUNITS at, the setting for -DWGUNITS will mess things up on you.

I was tearing my hair out for like forever trying to figure this one out.

-Murray Clack

har!s said...

Very nice information, atleast for the vetical people. Thanks for the input.