HPGL plots on LaserJet III's
Gerald Pearson (gpearson@umaxc.weeg.uiowa.edu)
Wed, 10 Nov 93 17:43:54 -0600
After seeing all the notes about HPGL plotters and alternatives during the
last month, I thought I'd put my two cents worth in.
DIFFERENT "PEN WIDTHS" ARE EASY TO DO.
The default line width produced by a LaserJet III when plotting HPGL is
too broad for good quality plots, because fine spectral detail is lost. I
also found to my dismay that it doesn't work to tell the printer to define
each "pen" as having a certain width, because the "width" of _all_ pens gets
changed to the most-recently-defined width!
Just after the LaserJet III was introduced a few years ago, I wrote a DOS
filter in C to take a stream of HPGL commands, slightly edit it, and produce a
stream of commands -- including all proper escape sequences -- to produce the
desired plot on a LaserJet III; everything except a few specific HPGL
commands is simply copied to the output without modification. Among other
things, the "select pen number n" command gets translated into "select pen
number 1", plus a command which sets a new width for the line. "Pen 1"
produces a line about 1 pixel wide, and "pen 8" draws quite a broad line.
We're still routinely using this program to produce plots from PCNMR+. From
within PCNMR+, the user can change the default "pens" selected for spectrum,
integrals, expansions, grid, text, comments, etc. Fine lines are desirable
for routine use, but broad lines are better for slides and overhead
transparencies.
I can't send you source code, because I somehow managed to loose it during one
of several moves to new computers, but I CAN EMAIL THE EXECUTABLE CODE TO
ANYONE WHO REQUESTS IT. I would email it in the form of a DEBUG script
(ordinary ascii text file). The MSDOS DEBUG utility can resurrect the
executable file (PLOT_III.COM, 7840 bytes) from the text file.
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Gerald A. Pearson INTERNET: gerald-pearson@uiowa.edu
Chem. Dept., Univ. of Iowa VOICE: 319-335-1336
Iowa City, IA 52242-1219, USA FAX: 319-335-1270
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