HPGL files designate different colors by setting pens. If you look inside your HPGL file, you will see the set pen command SP followed by a pen number, for example SP3, which means, ‘plot the following commands using pen number 3’. The default color for any pen number is black, but this can easily be set in the SwiftView configuration file using the ICS command hpgl pen. Place the following commands in your ini file (for standalone SwiftView) or your npsview.ics file (for web licenses):
hpgl pen 1 red 255 green 0 blue 0 width normal
hpgl pen 2 red 0 green 0 blue 255 width normal
hpgl pen 3 red 0 green 255 blue 0 width normal
hpgl pen 4 red 255 green 0 blue 255 width normal
If adding these commands to your local ini file, please be sure to format each command correctly.
If your document is missing lines, it is possible that the missing lines are being drawn with pen 0, which is white. To confirm this possibility, please add the set allpensblack enable command to your ini file and attempt to view the document again.