HP2XX, A HP-GL Converter
3.2 Fixed scaling
As noted earlier, hp2xx does not draw to scale, but rather it fits
a picture into a given limiting window. While this is very handy in most
applications, it may be undesirable when a series of pictures must be drawn
to the same scale. Unless all pictures possess the same picture limits
(modulo offsets), e.g., because all of them are surrounded by some fixed
frame, hp2xx would scale them all up differently to fit each of them
tightly into the limiting window.
There are two simple cures: First, make use of the true size option `-t'.
If the original HP-GL sizes do not fit, adjust picture limits to
guarantee a constant scaling: Make a preview of all pictures and note
the coordinate ranges hp2xx reports. Then, determine picture limits
which cover all of these individual limits. Finally, run hp2xx
to create your desired outputs using options `-xXyY' to tell
hp2xx about the picture limits it should use. If the pictures
do not share common offsets, you may have to correct for offsets
manually. Use the preview mode for testing. You'll get the same scale
as long as the limiting window and (xmax - xmin) and
(ymax - ymin) remain constant for all pictures.
WARNING: hp2xx does not clip lines (unless told to by the IW
directive of HPGL/2, of course). If the picture limits which
you manually can pre-set via options `-xXyY' are chosen too narrow,
they will be pushed outside just as described in the last section,
resulting in a different scale. Check the coordinate ranges hp2xx
reports. The should match the values supplied by options `-xXyY'!
