Re: Problem with PostScript output of surface plot

[Mike Miller]

On Fri, May 06, 2016 at 16:41:01 +0000, David M. Cook wrote:
> Apparently, I have inadvertently deleted your most recent response to
> my inquiry with the subject on this email (Could you perhaps resend
> it?), but I think I remember its content and would respond with the
> following two observations:

The list is archived, all messages are available at

  http://lists.gnu.org/archive/html/help-octave/

My last message is

  http://lists.gnu.org/archive/html/help-octave/2016-05/msg00036.html

> 1.  I have executed the script in my earlier email with all three
> graphics toolkits (qt, fltk, gnuplot), for all of which the command
> 'print -deps2 trial.eps' produces a PostScript file that exhibits the
> same inaccurate behavior when I display the output PostScript file in
> my version of ghostview. (Ghostview, Version 5.0, backed up by
> ghostscript, Version 9.07, which I believe are the most recent
> versions.)
> 
> Out of curiosity, I tried 'print -dpng trial.png', 'print -djpg
> trial.jpg', and 'print -dpdf trial.pdf', discovering that all three of
> those files exhibit the same shadowing, though not as prominently as
> the eps file.  There is no hint of this shadowing in the Figure window
> produced directly by OCTAVE.

Understood.

> 2.  I am using gnuplot because I want the PostScript files that are
> output to have the capacity to display Greek letters in the output
> files, which I am ultimately incorporating in LaTeX source files.
> From Section 15.2.8 of the Octave documentation accessible at the URL
> 
> https://www.gnu.org/software/octave/doc/v4.0.1/Use-of-the-interpreter-Property.html
> 
> I learn that "for on-screen display the interpreter property is
> honored by all graphics toolkits. However for printing, only the
> "gnuplot" toolkit renders TeX instructions."  I tested this feature
> with all three graphics toolkits.  It appears as if both gnuplot and
> fltk interpret Greek characters like \alpha but qt does not.

Right.

> Thanks for your help.  I am not sure where to go from here to correct
> the PostScript file I can generate.

All I know is there appears to be a known bug with "shading interp" with
the Octave gnuplot toolkit that has not yet been fixed. See

  https://savannah.gnu.org/bugs/?42316

So yes, you should avoid the OpenGL-based toolkits if you want to use
TeX markup. And you should avoid the gnuplot toolkit if you want to use
"shading interp". If those are both important to you, I don't have any
recommendations for how to continue, other than to help fix these bugs
in Octave.

-- 
mike