## 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} {} meshz (@var{x}, @var{y}, @var{z})
## Plot a curtain mesh 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 mesh.  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.
## @seealso{meshgrid, mesh, contour}
## @end deftypefn
 
function retval = meshz (varargin)

  [h, varargin, nargin] = __plt_get_axis_arg__ ("meshz", varargin{:});

  ioff = nargin + 1;
  for i = 1:nargin
    if (ischar (varargin{i}))
      ioff = i;
      break;
    endif
  endfor

  ## Bundle C matrix back into varargin
  if (ioff == 3 || ioff == 5)
    ioff --;
  endif

  if (ioff == 2)
    z = varargin{1};
    [m, n] = size (z);
    x = 1:n;
    y = (1:m).';
  else
    x = varargin{1};
    y = varargin{2};
    z = varargin{3};
  endif


  if (isvector (x) && isvector (y))
    x = [x(1), x(:).', x(end)];
    y = [y(1); y(:); y(end)];
  else
    x = [x(1, 1), x(1, :), x(1, end);
	 x(:, 1), x, x(:, end);
	 x(end, 1), x(end, :), x(end, end)]; 
    y = [y(1, 1), y(1, :), y(1, end);
	 y(:, 1), y, y(:, end);
	 y(end, 1), y(end, :), y(end, end)]; 
  endif

  zref = min(z(isfinite(z)));
  z = [zref .* ones(1, size(z, 2) + 2);
       zref .* ones(size(z, 1), 1), z, zref .* ones(size(z, 1), 1); 
       zref.* ones(1, size(z, 2) + 2)];

  oldh = gca ();
  unwind_protect
    axes (h);
    tmp = mesh (x, y, z, varargin{ioff:end});
  unwind_protect_cleanup
    axes (oldh);
  end_unwind_protect

  if (nargout > 0)
    retval = tmp;
  endif

endfunction
