C-PLOT

Scientific Graphics and Data Analysis

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|0
With 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.