## Copyright (C) 2004-2008,2009  Carlo de Falco, Massimiliano Culpo
##
##  This file is part of 
##
##                   FPL - Fem PLotting package for octave
## 
##  FPL 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.
## 
##  FPL 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 FPL; If not, see <http://www.gnu.org/licenses/>.
##
##
##  AUTHORS:
##  Carlo de Falco <cdf _AT_ users.sourceforge.net>
##
##  Culpo Massimiliano
##  Bergische Universitaet Wuppertal
##  Fachbereich C - Mathematik und Naturwissenschaften
##  Arbeitsgruppe fuer Angewandte MathematD-42119 Wuppertal  Gaussstr. 20 
##  D-42119 Wuppertal, Germany

## -*- texinfo -*-
## @deftypefn {Function File} {} FPL3dxoutputmesh ( @var{filename}, @
## @var{mesh} )
##
##  Outputs data in DX form.
##
## Variable must be a scalar, vector or tensor of doubles   
##
## @itemize @minus
##  @item @var{filename} = name of file to save (type string)
##  @item @var{mesh}     = PDE-tool like mesh
## @end itemize
## @end deftypefn


function FPL3dxoutputmesh(filename,mesh)

  nodes  = mesh.p';
  elem   = mesh.t(1:4,:)';

  fid    = fopen (filename,"w");
  nnodes = columns(mesh.p);
  nelem  = columns(mesh.t);

  fprintf(fid,"object ""pos""\nclass array type float rank 1 shape 3 items %d data follows",nnodes);
  for ii = 1:nnodes
    fprintf(fid,"\n");
    fprintf(fid,"    %e",nodes(ii,:));
  endfor

  ## In DX format nodes are numbered starting from zero,
  ## instead we want to number them starting from 1.
  if (min(min(elem))==1)
    elem = elem - 1;
  elseif(min(min(elem))~=0)
    error("WARNING: check tetrahedra structure");
  end                    

  fprintf(fid,"\n\nobject ""con""\nclass array type int rank 1 shape 4 items %d data follows",nelem);
  for ii = 1:nelem
    fprintf(fid,"\n");
    fprintf(fid,"      %d",elem(ii,:));
  endfor

  fprintf(fid,"\nattribute ""element type"" string ""tetrahedra""\nattribute ""ref"" string ""positions""\n\n");

  fprintf(fid,"object ""themesh"" class field\n");
  fprintf(fid,"component ""positions"" value ""pos""\n");
  fprintf(fid,"component ""connections"" value ""con""\n");

  fprintf(fid,"\nend\n");
  fclose (fid);

endfunction

%!test
%! msh.p =[ 0   0   1   1   0   0   1   1
%!	    0   1   0   1   0   1   0   1
%!	    0   0   0   0   1   1   1   1];
%! msh.e =[1   5   7   8   5   5   6   8   1   3   5   7
%! 	   2   6   3   3   7   3   2   6   3   2   6   6
%!         6   1   8   4   3   1   4   4   2   4   7   8
%!         0   0   0   0   0   0   0   0   0   0   0   0
%!         0   0   0   0   0   0   0   0   0   0   0   0
%!         0   0   0   0   0   0   0   0   0   0   0   0
%!         0   0   0   0   0   0   0   0   0   0   0   0
%!         0   0   0   0   0   0   0   0   0   0   0   0
%!         1   1   1   1   1   1   1   1   1   1   1   1
%!         1   1   2   2   3   3   4   4   5   5   6   6];
%! msh.t =[ 1   5   5   6   7   8
%!          3   6   6   3   3   3
%!          2   7   3   2   6   6
%!          6   3   1   4   8   4
%!          1   1   1   1   1   1];
%! testfile = "object ""pos""\nclass array type float rank 1 shape 3 items 8 data follows\n    0.000000e+00    0.000000e+00    0.000000e+00\n    0.000000e+00    1.000000e+00    0.000000e+00\n    1.000000e+00    0.000000e+00    0.000000e+00\n    1.000000e+00    1.000000e+00    0.000000e+00\n    0.000000e+00    0.000000e+00    1.000000e+00\n    0.000000e+00    1.000000e+00    1.000000e+00\n    1.000000e+00    0.000000e+00    1.000000e+00\n    1.000000e+00    1.000000e+00    1.000000e+00\n\nobject ""con""\nclass array type int rank 1 shape 4 items 6 data follows\n      0      2      1      5\n      4      5      6      2\n      4      5      2      0\n      5      2      1      3\n      6      2      5      7\n      7      2      5      3\nattribute ""element type"" string ""tetrahedra""\nattribute ""ref"" string ""positions""\n\nobject ""themesh"" class field\ncomponent ""positions"" value ""pos""\ncomponent ""connections"" value ""con""\n\nend\n";
%! FPL3dxoutputmesh ("__FPL3dxoutputmesh__test__.dx",msh);
%! fid = fopen("__FPL3dxoutputmesh__test__.dx","r"); 
%! s = fread(fid);
%! fclose(fid); 
%! assert (char(s'), testfile);
%! delete __FPL3dxoutputmesh__test__.dx