## Copyright (C) 2010 Kurnia Wano, Levente Torok
##.
## 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 Octave; see the file COPYING. If not, see <http://www.gnu.org/licenses/>.
##

## -*- texinfo -*-
## @deftypefn {Function File} [ @var{status} ] = savevtkvector ( @var{X}, @var{Y}, @var{Z}, @var{filename} )
##  savevtkvector Save a 3-D vector array in VTK format
##
##  savevtkvector (X, Y, Z, filename) saves a 3-D vector of any size to
##  filename in VTK format. This file format is used by Mayavi2 for example.
##  X, Y and Z should be arrays of the same
##  size, each storing speeds in the a single Cartesian directions.
##
##  If no write errors occurred, output argument status is set to 1, otherwise 0.
##
## @end deftypefn

##
## Author: Kurnia Wano, Levente Torok <address@hidden>
## Created: 2010-08-02 matlab version
## Updates: 2010-11-03 octave adoptatoin
##

function [ status ] = savevtkvector (X, Y, Z, filename)

	status = 0;
	if (nargin < 4), usage ("[status] = savevtkvector (X, Y, Z, filename='vtkvector.out')"); endif
    if ((size(X) ~= size(Y)) | (size(X) ~= size(Z)))
        error ("Error: velocity arrays of unequal size\n");
#        return;  return not needed here, error() breaks out already
    end
    [ny, nx, nz] = size (datax);
    xx = 1:size (datax, 2);
    yy = 1:size (datax, 1);
    zz = 1:size (datax, 3);
    datax = datax(:)';
    datay = datay(:)';
    dataz = dataz(:)';
    ## Header

	if (ischar (filename))
		[ fid, msg ] = fopen (fullfile (outputd, filename), 'w');
		if ( fid < 1 )
			error ("Cannot open the file for saving: %s", msg);
		endif
	else
		usage ("Filename expected for arg # 2");
	endif

	try
		fprintf (fid, '%s\n', '# vtk DataFile Version 3.0');
		fprintf (fid, '%s\n', '3D LFF extrapolation');
		fprintf (fid, '%s\n', 'ASCII' );
		fprintf (fid, '%s\n', 'DATASET RECTILINEAR_GRID');
		fprintf (fid, '%s %1.0i %1.0i %1.0i\n', 'DIMENSIONS',nx, ny, nz);
		fprintf (fid, '%s %1.0i %s\n', 'X_COORDINATES', nx, 'float');
		fprintf (fid, '%1.0i ', xx);
		fprintf (fid, '\n%s %1.0i %s\n', 'Y_COORDINATES', ny, 'float');
		fprintf (fid, '%1.0i ', yy);
		fprintf (fid, '\n%s %1.0i %s\n', 'Z_COORDINATES', nz, 'float');
		fprintf (fid, '%1.0i ', zz);
		## Data
		fprintf (fid, '\n%s %1.0i','POINT_DATA', nx*ny*nz );
		fprintf (fid, '\n%s\n', 'VECTORS BFIELD float');
		fprintf (fid, '%6.2f %6.2f %6.2f\n', [datax;datay;dataz]);
		fclose (fid);
		status = 1;
	catch
		error ("Error writing file %s - disk full?", filename)
	end_try_catch

endfunction