|The other day, as I was scheming to
outwit Generic CADD into letting me use a tolerance of 9 inches (on a 13 inch
monitor, almost everything is within 9 inches), I wondered to myself, do other
users do this?
Generic CADD limits the tolerance to between 0 and 1. Valus in this range are suffient for most cases, but not always. For example, when writing macros, I'm not always sure that the intersection I am looking for will be within an inch. The technique by which you can "trick" Generic CADD into a really large tolerance is the topic then, of this column.
You see, there is no mathematical reason that you can't have a tolerance as big as you want. Many values are simply limited in one way or another to keep you from getting into too much trouble. Besides, no one would want a tolerance of more than one inch, would they?
When you first start up Generic CADD, many of the default parameter values are read in from the configuration file. These values can be set with the CONFIG program, including along with Generic CADD. But the CONFIG program is limited by the same constraints that Generic CADD is - you still can't specify a tolerance greater than 1. The configuration file itself, however, is another story.
The configuration program makes an ASCII file (fortuitous, eh?) called CONFIG.FIL that is read by Generic CADD to set the default values. This file is chock full of comments that tell you what each value does, and it is easy to edit with a word processor that reads and writes ASCII files.
The seventh line of CONFIG.FIL contains the GRIG (sic) SIZE and the TOLERANCE. To change the tolerance to 9, just change the second value on the line to 9.0000. Be careful no to change anything else, or to ad or delete any other characters. You have to be sneaky. Don't arouse Generic CADD's suspicions if you expect this to work.
With the new CONFIG.FIL ready to go, start up Generic CAD and try out a few SNAP CENTER commands from across the screen. You will see that the tolerance is really large. If you want to keep the large tolerance, DON'T use the Tolerance command, however, as Generic CADD will notice the illegal value and trick you back by automatically setting it to 1. To change the tolerance outside this range, bo back and edit CONFIG.FIL.
Once you have the hang of it, you will soon be using decimal values in pure integer form (DV=0), upside down text (negative TZ), dimensions with zero or negative offsets (negative XO), and extension lines with zero length (XL=0). These are a few of the illegal values that can be defined in this way. Just remember not to use the associated command in CADD, and forget about negative Limits...you won't be able to move the cursor. I tried it.