TrueType font caution

["K. Bowman" <k-bowman(at)null.tamu.edu>]

As has been pointed out a few times in this group, the IDL TrueType
fonts, unlike PostScript fonts, will plot correctly in 3D plots. 
Because of this advantage, I thought it would be easiest to do all PS
plots using TT fonts.  This turned out not to be the case.

The manuals indicate that IDL draws TT fonts by tesselating the font
characters and drawing the necessary polygons to create each individual
character.  I don't know how the PS device handles PS fonts, but I
expect it leaves the rasterization up to the output device.

>From my experience, this has several implications:

1.  PS files created using TT fonts are much larger than the same plots
using PS fonts, presumably because of all the polygons that must be
written.  I was unable to combine two plots that use TT fonts (i.e.,
two panels for a publication figure) in Illustrator even with 180 MB
allotted for Illustrator on my Mac G4.  I had no trouble doing the same
thing with PS fonts.

2.  Because TT text is actually polygons, it cannot be manipulated in a
drawing program like Illustrator using the font commands.  That is, you
can't change the point size, alignment, etc.  You can group, scale and
move the polygons, but that is less than ideal.

Therefore, my recommendation is that when creating PS files, PS fonts
should be used for 2D plots, while TT fonts should be used for 3D
plots.  This requires some additional (annoying) DEVICE and !P.FONT
commands if you make both kinds of plots in the same program.

Ken