From octave-sources-request at bevo dot che dot wisc dot edu Fri Apr 11 10:06:01 2003
Subject: Colormap for z-coloured surf plot (gnuplot 3.8+)
From: fabio rainone <fabio dot rainone at epfl dot ch>
To: octave-sources at bevo dot che dot wisc dot edu
Date: Fri, 11 Apr 2003 03:15:41 -0500

Hi folks!!

I just derived from colormap a new function that is capable to modify
the palette used by the new 3D plot function in GNUplot, pm3d.
This allow very good mimicking of the MATLAB surf/colormap capabilities

## Copyright (C) 2003 Fabio Rainone
##
## This program is free software; you can redistribute it and/or modify
## it under the terms of the GNU General Public License as published by
## the Free Software Foundation; either version 2 of the License, or
## (at your option) any later version.
##
## This program is distributed in the hope that it will be useful,
## but WITHOUT ANY WARRANTY; without even the implied warranty of
## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
## GNU General Public License for more details.
##
## You should have received a copy of the GNU General Public License
## along with this program; if not, write to the Free Software
## Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA

## -*- texinfo -*-
##  at deftypefn {Function File} {} gcolormap(@var{map})
##  at deftypefnx {Function File} {} gcolormap("default")
##  at code{gcolormap(@var{map})} sets the current colormap for z-coloured plots
## in Gnuplot 3.8+.  at var{map} should be an @var{n} row per 3 column vector.
## Each row contains an RGB triplet expressed in the range [0, 1]
##
##  at code{gcolormap("default") sets the colormap to the default (grayscale)
##
## With no arguments,  at code{gcolormap} returns the current colormap
##  at end deftypefn
##  at seealso {colormap}

## Author: Fabio Rainone
## LGRC - EPFL - Switzerland
## Created April 2003


function rmap = gcolormap(map)

   global __gnuplot_colormap__= gray();

   ##Bad argument list
   if(nargin>1)
     usage("gcolormap (map)");
   endif

   if (nargin ==1)

     #The palette is given by name
     if(isstr(map))
       if(strcmp(map, "default"))
         map = gray();
       elseif(exist(map)==2) ##if map is a function file
         unwind_protect
           save__eval_print_flag = default_eval_print_flag;
           default_eval_print_flag = 0;
           map = eval(map);
         unwind_protect_cleanup
           default_eval_print_flag = save__eval_print_flag;
         end_unwind_protect
       else  ##any other case is a error
         error("gcolormap: unknown colormap function");
       endif ##exist(map)

     endif ##isstr(map)

     ##The palette is given as matrix
     if(  isempty(map) || (columns(map)~=3)  )
       error("gcolormap: Palette matrix must be 3 columns wide!")
     elseif (min (map(:)) < 0 || max (map(:)) > 1)
       error("gcolormap: r g b must be scaled in [0 1] range");
     else
       __gnuplot_colormap__ = map;
     endif


     try
       gset palette model RGB file "-"
       graw ([sprintf("%5.4f %5.4f %5.4f\n", __gnuplot_colormap__') "e\n"]);
     catch
     end_try_catch
   endif ## nargin==1
   rmap = __gnuplot_colormap__;
endfunction


Fabio Rainone,
SB - ISP - LGRC
Swiss Federal Institute of Technology
CH-1015 Lausanne (Switzerland)