From graphics-request at octave dot org Wed Sep 28 07:33:30 2005
Subject: Re: Multicolor mesh plot patch
From: Petr Mikulik <mikulik at physics dot muni dot cz>
To: Quentin Spencer <qspencer at ieee dot org>
cc: "John W. Eaton" <jwe at bevo dot che dot wisc dot edu>, bug@octave.org,         graphics@octave.org
Date: Wed, 28 Sep 2005 14:30:27 +0200 (CEST)

>>> | features. The attached patch makes mesh use color lines. It also defines
>>> | a color palette that is very similar to Matlab's default palette. I
>>> | don't know if this is the best way to do this, I'm open to suggestions
>>> | on how to improve it.
>> 
>> 
>> I propose you let
>>    __gnuplot_set__ colorbox
>> instead of nocolorbox ... colorbox is a very useful thing and without it 
>> you are looking at a "blind" image.
>
> The theory behind my doing this was Matlab compatibility--by default Matlab 
> plots have no colorbox, but the command "colorbar" adds one. (For the same 
> reason, I think that by default we should have "set nokey" for all plots, and 
> the "legend" command used to add them).

Does  hold on|off  work with these commands?
Otherwise, the scheme "colorbox; replot" is a waste of time.

>> I'd like to say I do not like that the recent Octave removed gset/graw 
>> commands. Without them, no nice (publication quality) plots can be 
>> produced. 
>
> They can with the print command (in octave-forge).

The "publication quality" you get can with more fine tuning, like gset 
commands or "handles".

> I agree it would be nice to use a different image function that uses gnuplot 
> instead of ImageMagick. I once tried doing this with gnuplot 4.0 and found 
> that it can work, but it's painfully slow for larger data sets because of the 
> text file method of data transfer. Once again, we're also facing the problem 
> that imagegp.m apparently requires the non-existent gnuplot 4.1 that may not 
> exist for a while yet

imagegp + gnuplot 4.1 works very well even for large images (1024x1024).
The test for version 4.1 works fine.

> OTOH, I suppose we could offer a --without-gnuplot
> option similar to the --without-readline option.

Ok, and if --with-gnuplot, then it should require gnuplot 4.0.

> The gset and other gXXX commands are going away in Octave 3.0.

This means, they will have to be written as user functions (.m files)
in order to keep compatibility with old scripts; and kept inside the
"gnuplot backend" scripts directory.

> That way, the rendering of the plot is separated from the generation of
> data. Modifying the plot doesn't require repeating the calculation, which
> might take a long time to do.

On the other hand, there are frequently cases where you want to print data,
those generation is easy but storing much more consuming (case of images).

---
PM