From graphics-request at octave dot org Mon Sep 26 16:21:44 2005
Subject: Multicolor mesh plot patch
From: Quentin Spencer <qspencer at ieee dot org>
To: bug at octave dot org, graphics@octave.org
Date: Mon, 26 Sep 2005 16:17:44 -0500

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I'm not sure which list is best for this, so I'm sending it to bug and 
graphics. Someone recently was complaining about the quality of mesh 
plots, and I agree the two-color plots don't look that great. I 
discovered that this can be changed quite easily using gnuplot 4.0 
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. One thing that's missing is a check for whether 
the "palette" line type is valid. The octave-forge functions surf and 
surfc use a global gnuplot_has_pm3d, but it's a bit of a hack and I 
doubt John wants stuff like this in core Octave code. Is there any way 
to verify the capabilities of gnuplot from octave? We have things like 
OCTAVE_VERSION and OCTAVE_FORGE_VERSION defined, would it make sense to 
define GNUPLOT_VERSION?

-Quentin



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Index: mesh.m
===================================================================
RCS file: /cvs/octave/scripts/plot/mesh.m,v
retrieving revision 1.31
diff -u -r1.31 mesh.m
--- a/mesh.m    15 Jun 2005 03:49:23 -0000      1.31
+++ b/mesh.m    26 Sep 2005 20:54:59 -0000
 at @ -75,7 +75,10 @@
         __gnuplot_raw__ ("set nologscale;\n");
         __gnuplot_set__ parametric;
         __gnuplot_raw__ ("set view 60, 30, 1, 1;\n");
-        __gnuplot_splot__ (zz);
+        __gnuplot_set__ palette defined ( 0 "dark-blue", 1 "blue", ...
+                  2 "cyan", 3 "yellow", 4 "red" , 5 "dark-red" )
+        __gnuplot_set__ nocolorbox
+        __gnuplot_splot__ zz with line palette;
         __gnuplot_set__ noparametric;
       else
         msg = "mesh: rows (z) must be the same as length (y) and";

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