10.6. - ch change target of drawing commands
causes all subsequent graphics filter
z commands, whether entered
from the keyboard or a command file, to be treated as pen plotter
p commands, or vice versa.
ch or ch z|p|0With no arguments, C-PLOT indicates whether or not the commands are being changed. A
z argument causes
HP-GL
plotter
p commands to be treated as graphics filter
z commands.
A
p argument does the reverse.
An argument of
0 makes the
p and
z commands work normally.
When changing
from
z to
p, the
erase
command,
ze, the
window erase
command,
zE and the
quiet
command,
zq, are ignored.
When changing from
p to
z, the
select pen velocity
command,
pv, is ignored.
You may, for example, wish to use a graphics filter to display the plot on a video terminal while developing a command file. When the command file is fine tuned, you can use the change target command to make the plot program substitute pen-plotter
p commands for
the
z commands when it executes the command file.
The
ch command also can be useful for debugging a
z-based command file, by changing the target of the drawing command to the
pen plotter with no pen plotter initialized.
In this case, nothing
will be drawn, but you will be able to observe error messages on the
screen that might otherwise be obscured by graphics.
Also, quiet mode
(invoked by the
zq command) doesn't turn off printing of messages
when the pen plotter is the drawing target.