--- a/scripts/ChangeLog
+++ b/scripts/ChangeLog
@@ -1,3 +1,18 @@
+2007-11-14  David Bateman  <dbateman@free.fr>
+
+	* plot/__contour__.m: Treat unclosed contours by adding NaN to
+	flag to patch that it is not closed. Allow z to take string
+	arguments and use it to flag that the contours are placed at the
+	z level of the contour itself.
+	* plot/__go_draw_axes__.m: Treat hidden line removal in patch
+	objects as well. Let hidden removal take precedence in case of a
+	conflict.
+	* plot/surface.m: Allow surface to treat handles being passed or
+	returned. Any additional arguments arr used to set the surface
+	handle.
+	* plot/contour3.m: New function
+	* plot/Makefile.in (SOURCES): Add it to the sources.
+
 2007-11-14  John W. Eaton  <jwe@octave.org>
 
 	* specfun/bessel.m: Update doc string from

--- a/scripts/plot/Makefile.in
+++ b/scripts/plot/Makefile.in
@@ -72,6 +72,7 @@
   clf.m \
   close.m \
   closereq.m \
+  contour3.m \
   contour.m \
   contourc.m \
   contourf.m \

--- a/scripts/plot/__contour__.m
+++ b/scripts/plot/__contour__.m
@@ -23,6 +23,21 @@
   ax = varargin {1};
   z = varargin {2};
 
+  if (ischar (z))
+    if (strcmp (z, "none"))
+      z = NaN;
+    elseif (strcmp (z, "base"))
+      if (nargin == 1)
+	z = varargin {1};
+      else
+	z = varargin {3};
+      endif
+      z = 2 * (min(z(:)) - max(z(:)));
+    elseif (!strcmp (z, "level"))
+      error ("unrecognized z argument");
+    endif
+  endif
+
   clim = get (ax, "clim");
 
   [c, lev] = contourc (varargin{3:end});
@@ -36,15 +51,23 @@
     clev = c(1,i1);
     clen = c(2,i1);
 
-    ii = i1+1:i1+clen;
+    if (all (c(:,i1+1) == c(:,i1+clen)))
+      p = c(:, i1+1:i1+clen-1);
+    else
+      p = [c(:, i1+1:i1+clen), NaN(2, 1)];
+    endif
+
     lev = (clev - minlev) * (clim(2) - clim(1)) / (maxlev - minlev) + clim(1);
 
     if (isnan (z))
-      h = [h; patch(ax, c(1,ii), c(2,ii), "facecolor", "none", 
+      h = [h; patch(ax, p(1,:), p(2,:), "facecolor", "none", 
 		    "edgecolor", "flat", "cdata", lev)];
+    elseif (!ischar(z))
+      h = [h; patch(ax, p(1,:), p(2,:), z * ones (1, columns (p)), "facecolor",
+		    "none", "edgecolor", "flat", "cdata", lev)];
     else
-      h = [h; patch(ax, c(1,ii), c(2,ii), z*ones(size(ii)), "facecolor",
-		    "none", "edgecolor", "flat", "cdata", lev)];
+      h = [h; patch(ax, p(1,:), p(2,:), clev * ones (1, columns (p)),
+		    "facecolor", "none", "edgecolor", "flat", "cdata", lev)];
     endif
     i1 += clen+1;
   endwhile

--- a/scripts/plot/__go_draw_axes__.m
+++ b/scripts/plot/__go_draw_axes__.m
@@ -204,7 +204,7 @@
     data_idx = 0;
     data = cell ();
     is_image_data = [];
-    hidden_removal = true;
+    hidden_removal = NaN;
 
     xminp = yminp = zminp = cminp = Inf;
     xmax = ymax = zmax = cmax = -Inf;
@@ -461,7 +461,12 @@
 
 	   if (! isnan (xcol) && ! isnan (ycol))
 	     ## Is the patch closed or not
-	     if (! strncmp (obj.facecolor, "none", 4)) 
+	     if (strncmp (obj.facecolor, "none", 4)) 
+	       if (isnan (hidden_removal))
+		 hidden_removal = false;
+	       endif
+	     else
+	       hidden_removal = true;
 	       if (! isempty (zcol))
 		 error ("gnuplot (as of v4.2) only supports 2D filled patches");
 	       else
@@ -747,7 +752,11 @@
             palette_data = [];
 
 	    if (strncmp (obj.facecolor, "none", 4))
-	      hidden_removal = false;
+	      if (isnan (hidden_removal))
+		hidden_removal = false;
+	      endif
+	    else
+	      hidden_removal = true;
 	    endif
 
             if (flat_interp_face
@@ -895,7 +904,7 @@
 
     endfor
 
-    if (hidden_removal)
+    if (isnan(hidden_removal) || hidden_removal)
       fputs (plot_stream, "set hidden3d;\n");
     else
       fputs (plot_stream, "unset hidden3d;\n");

new file mode 100644
--- /dev/null
+++ b/scripts/plot/contour3.m
@@ -0,0 +1,77 @@
+## Copyright (C) 2007 David BAteman
+##
+## This file is part of Octave.
+##
+## Octave 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 3 of the License, or (at
+## your option) any later version.
+##
+## Octave 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 Octave; see the file COPYING.  If not, see
+## <http://www.gnu.org/licenses/>.
+
+## -*- texinfo -*-
+## @deftypefn {Function File} {@var{c} =} contour3 (@var{z})
+## @deftypefnx {Function File} {@var{c} =} contour3 (@var{z}, @var{vn})
+## @deftypefnx {Function File} {@var{c} =} contour3 (@var{x}, @var{y}, @var{z})
+## @deftypefnx {Function File} {@var{c} =} contour3 (@var{x}, @var{y}, @var{z}, @var{vn})
+## @deftypefnx {Function File} {@var{c} =} contour3 (@var{h}, @dots{})
+## @deftypefnx {Function File} {[@var{c}, @var{h}] =} contour3 (@dots{})
+## Plot level curves (contour lines) of the matrix @var{z}, using the
+## contour matrix @var{c} computed by @code{contourc} from the same
+## arguments; see the latter for their interpretation.  The contours are
+## ploted at the Z level corresponding to their contour. The set of
+## contour levels, @var{c}, is only returned if requested.  For example:
+##
+## @example
+## @group
+## contour3 (peaks (19));
+## hold on
+## surface (peaks (19), 'FaceColor', 'none', 'EdgeColor', 'black')
+## colormap hot
+## @end group
+## @end example
+##
+## The optional input and output argument @var{h} allows an axis handle to 
+## be passed to @code{contour} and the handles to the contour objects to be
+## returned.
+## @seealso{contourc, patch, plot}
+## @end deftypefn
+
+function [c, h] = contour3 (varargin)
+
+  if (isscalar (varargin{1}) && ishandle (varargin{1}))
+    ax = varargin{1};
+    if (! strcmp (get (ax, "type"), "axes"))
+      error ("contour: expecting first argument to be an axes object");
+    endif
+    oldh = gca ();
+    unwind_protect
+      axes (ax);
+      newplot ();
+      [ctmp, htmp] = __contour__ (ax, varargin{2:end});
+    unwind_protect_cleanup
+      axes (oldh);
+    end_unwind_protect
+  else
+    newplot ();
+    ax = gca ();
+    [ctmp, htmp] = __contour__ (ax, "level", varargin{:});
+  endif
+
+  if (! ishold ())
+    set (ax, "view", [-37.5, 30]);
+  endif
+
+  if (nargout > 0)
+    c = ctmp;
+    h = htmp
+  endif
+
+endfunction

--- a/scripts/plot/surface.m
+++ b/scripts/plot/surface.m
@@ -18,49 +18,48 @@
 ## <http://www.gnu.org/licenses/>.
 
 ## -*- texinfo -*-
-## @deftypefn {Function File} @var{h} = {} surface (@var{x}, @var{y}, @var{z}, @var{c})
-## @deftypefnx {Function File} @var{h} = {} surface (@var{x}, @var{y}, @var{z})
-## Plot a surface graphic object given matrices @var{x}, and @var{y} from @code{meshgrid} and
-## a matrix @var{z} corresponding to the @var{x} and @var{y} coordinates of
-## the surface.  If @var{x} and @var{y} are vectors, then a typical vertex
-## is (@var{x}(j), @var{y}(i), @var{z}(i,j)).  Thus, columns of @var{z}
-## correspond to different @var{x} values and rows of @var{z} correspond
-## to different @var{y} values.
+## @deftypefn {Function File} {} surface (@var{x}, @var{y}, @var{z}, @var{c})
+## @deftypefnx {Function File} {} surface (@var{x}, @var{y}, @var{z})
+## @deftypefnx {Function File} {} surface (@var{z}, @var{c})
+## @deftypefnx {Function File} {} surface (@var{z})
+## @deftypefnx {Function File} {} surface (@dots{}, @var{prop}, @var{val})
+## @deftypefnx {Function File} {} surface (@var{h}, @dots{})
+## @deftypefnx {Function File} {@var{h} = } surface (@dots{})
+## Plot a surface graphic object given matrices @var{x}, and @var{y} from 
+## @code{meshgrid} and a matrix @var{z} corresponding to the @var{x} and 
+## @var{y} coordinates of the surface.  If @var{x} and @var{y} are vectors,
+## then a typical vertex  is (@var{x}(j), @var{y}(i), @var{z}(i,j)).  Thus, 
+## columns of @var{z} correspond to different @var{x} values and rows of 
+## @var{z} correspond to different @var{y} values. If @var{x} and @var{y}
+## are missing, they are constructed from size of the matrix @var{z}.
+##
+## Any additional properties passed are assigned the the surface..
 ## @seealso{surf, mesh, patch, line}
 ## @end deftypefn
 
 ## Author: jwe
 
-function h = surface (x, y, z, c)
+function h = surface (varargin)
 
   ax = gca ();
 
-  if (nargin == 1)
-    c = z = x;
-    if (ismatrix (z))
-      [nr, nc] = size (z);
-      x = 1:nc;
-      y = (1:nr)';
-    else
-      error ("surface: argument must be a matrix");
+  firststring = nargin + 1;
+  for i = 1 : nargin
+    if (ischar (varargin {i}))
+      firststring = i;
+      break;
     endif
-  elseif (nargin == 3)
-    c = z;
-    if (isvector (x) && isvector (y) && ismatrix (z))
-      if (rows (z) == length (y) && columns (z) == length (x))
-        x = x(:)';
-        y = y(:);
-      else
-        error ("surface: rows (z) must be the same as length (y) and columns (z) must be the same as length (x)");
-      endif
-    elseif (ismatrix (x) && ismatrix (y) && ismatrix (z))
-      if (! (size_equal (x, y) && size_equal (x, z)))
-        error ("surface: x, y, and z must have same dimensions");
-      endif
-    else
-      error ("surface: x and y must be vectors and z must be a matrix");
-    endif
-  elseif (nargin == 4)
+  endfor
+
+
+  if (firststring > 5)
+    print_usage ();
+  elseif (firststring == 5)
+    x = varargin{1};
+    y = varargin{2};
+    z = varargin{3};
+    c = varargin{4};
+
     if (! size_equal (z, c))
       error ("surface: z and c must have same size");
     endif
@@ -78,6 +77,45 @@
     else
       error ("surface: x and y must be vectors and z must be a matrix");
     endif
+  elseif (firststring == 4)
+    x = varargin{1};
+    y = varargin{2};
+    z = varargin{3};
+    c = z;
+    if (isvector (x) && isvector (y) && ismatrix (z))
+      if (rows (z) == length (y) && columns (z) == length (x))
+        x = x(:)';
+        y = y(:);
+      else
+        error ("surface: rows (z) must be the same as length (y) and columns (z) must be the same as length (x)");
+      endif
+    elseif (ismatrix (x) && ismatrix (y) && ismatrix (z))
+      if (! (size_equal (x, y) && size_equal (x, z)))
+        error ("surface: x, y, and z must have same dimensions");
+      endif
+    else
+      error ("surface: x and y must be vectors and z must be a matrix");
+    endif
+  elseif (firststring == 3)    
+    z = varargin {1};
+    c = varargin {2};
+    if (ismatrix (z))
+      [nr, nc] = size (z);
+      x = 1:nc;
+      y = (1:nr)';
+    else
+      error ("surface: argument must be a matrix");
+    endif
+  elseif (firststring == 2)    
+    z = varargin {1};
+    c = z;
+    if (ismatrix (z))
+      [nr, nc] = size (z);
+      x = 1:nc;
+      y = (1:nr)';
+    else
+      error ("surface: argument must be a matrix");
+    endif
   else
     print_usage ();
   endif
@@ -85,6 +123,7 @@
   ## Make a default surface object.
   tmp = __go_surface__ (ax, "xdata", x, "ydata", y, "zdata", z, "cdata", c);
   set (tmp, "facecolor","flat");
+  set (tmp, varargin {firststring:end});
 
   if (! ishold ())
     set (ax, "view", [0, 90], "box", "off", "xgrid", "on", "ygrid", "on", "zgrid", "on");