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##
## Copyright (C) 2021-2022 The Octave Project Developers
##
## See the file COPYRIGHT.md in the top-level directory of this
## distribution or <https://octave.org/copyright/>.
##
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## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
## GNU General Public License for more details.
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## You should have received a copy of the GNU General Public License
## along with Octave; see the file COPYING.  If not, see
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########################################################################

## -*- texinfo -*-
## @deftypefn  {} {} fill3 (@var{x}, @var{y}, @var{z}, @var{c})
## @deftypefnx {} {} fill3 (@var{x1}, @var{y1}, @var{z1}, @var{c1}, @var{x2}, @var{y2}, @var{z2}, @var{c2})
## @deftypefnx {} {} fill3 (@dots{}, @var{prop}, @var{val})
## @deftypefnx {} {} fill3 (@var{hax}, @dots{})
## @deftypefnx {} {@var{h} =} fill3 (@dots{})
## Create one or more filled 3-D polygons.
##
## The inputs @var{x}, @var{y}, and @var{z} are the coordinates of the polygon
## vertices.  If the inputs are matrices then the rows represent different
## vertices and each column produces a different polygon.  @code{fill3} will
## close any open polygons before plotting.
##
## The input @var{c} determines the color of the polygon.  The simplest form
## is a single color specification such as a @code{plot} format or an
## RGB-triple.  In this case the polygon(s) will have one unique color.  If
## @var{c} is a vector or matrix then the color data is first scaled using
## @code{caxis} and then indexed into the current colormap.  A row vector will
## color each polygon (a column from matrices @var{x}, @var{y}, and @var{z})
## with a single computed color.  A matrix @var{c} of the same size as @var{x},
## @var{y}, and @var{z} will compute the color of each vertex and then
## interpolate the face color between the vertices.
##
## Multiple property/value pairs for the underlying patch object may be
## specified, but they must appear in pairs.  The full list of properties is
## documented at @ref{Patch Properties}.
##
## If the first argument @var{hax} is an axes handle, then plot into this axes,
## rather than the current axes returned by @code{gca}.
##
## The optional return value @var{h} is a vector of graphics handles to
## the created patch objects.
##
## Example: oblique red rectangle
##
## @example
## @group
## vertices = [0 0 0
##             1 1 0
##             1 1 1
##             0 0 1];
## fill3 (vertices(:,1), vertices(:,2), vertices(:,3), "r");
## axis ([-0.5 1.5, -0.5 1.5, -0.5 1.5]);
## axis ("equal");
## grid ("on");
## view (-80, 25);
## @end group
## @end example
##
## @seealso{patch, fill, caxis, colormap}
## @end deftypefn

function h = fill3 (varargin)

  [hax, varargin] = __plt_get_axis_arg__ ("fill3", varargin{:});

  hlist = [];
  iargs = __find_patches__ (varargin{:});

  opts = {};
  if (numel (varargin) > iargs(end) + 3)
    opts = varargin(iargs(end)+4 : end);
  endif

  if (! all (cellfun (@(x) iscolorspec (x), varargin(iargs + 3))))
    print_usage ();
  endif

  oldfig = [];
  if (! isempty (hax))
    oldfig = get (0, "currentfigure");
  endif
  unwind_protect
    hax = newplot (hax);
    old_nxtplt = get (hax, "nextplot");
    if (! ishold ())
      set (hax, "box", "on");
    endif
    unwind_protect
      set (hax, "nextplot", "add");

      for i = 1 : length (iargs)
        x = varargin{iargs(i)};
        y = varargin{iargs(i) + 1};
        z = varargin{iargs(i) + 2};
        cdata = varargin{iargs(i) + 3};

        if (! size_equal (x, y, z))
          if (rows (x) != rows (y) || rows (x) != rows (z))
            error ("fill3: X, Y, and Z must have same number of rows");
          endif

          num_cols = max ([columns(x), columns(y), columns(z)]);
          if (iscolumn (x))
            x = repmat (x, [1, num_cols]);
          endif
          if (iscolumn (y))
            y = repmat (y, [1, num_cols]);
          endif
          if (iscolumn (z))
            z = repmat (z, [1, num_cols]);
          endif
        endif

        if (isrow (x))
          x = x(:);
        endif
        if (isrow (y))
          y = y(:);
        endif
        if (isrow (z))
          z = z(:);
        endif

        if (ischar (cdata) || isequal (size (cdata), [1, 3]))
          one_color = true;
        else
          one_color = false;
        endif

        ## For Matlab compatibility, replicate cdata to match size of data
        if (! one_color && iscolumn (cdata))
          sz = size (x);
          if (all (sz > 1))
            cdata = repmat (cdata, [1, sz(2)]);
          endif
        endif

        ## For Matlab compatibility, return 1 patch object for each column
        for j = 1 : columns (x)
          if (one_color)
            [htmp, err] = __patch__ (hax, x(:,j), y(:,j), z(:,j), ...
                                     cdata, opts{:});
          else
            [htmp, err] = __patch__ (hax, x(:,j), y(:,j), z(:,j), ...
                                     cdata(:,j), opts{:});
          endif
          if (err)
            print_usage ();
          endif
          hlist(end+1, 1) = htmp;
        endfor
      endfor

      view (hax, 3);

    unwind_protect_cleanup
      if (strcmp (old_nxtplt, "replace"))
        set (hax, "nextplot", old_nxtplt);
      endif
    end_unwind_protect

  unwind_protect_cleanup
    if (! isempty (oldfig))
      set (0, "currentfigure", oldfig);
    endif
  end_unwind_protect

  if (nargout > 0)
    h = hlist;
  endif

endfunction

function iargs = __find_patches__ (varargin)
  iargs = 1:4:nargin;
  optidx = find (! cellfun (@isnumeric, varargin(iargs)), 1);
  iargs(optidx:end) = [];
endfunction

function retval = iscolorspec (arg)

  retval = false;
  if (ischar (arg))
    persistent colors = {"y", "yellow", "r", "red", "m", "magenta", ...
                         "c", "cyan", "g", "green", "b", "blue", ...
                         "w", "white", "k", "black"};
    if (any (strcmpi (arg, colors)))
      retval = true;
    endif
  elseif (isnumeric (arg))
    ## Assume any numeric argument is correctly formatted cdata.
    ## Let patch worry about the multiple different input formats.
    retval = true;
  endif

endfunction


%!demo
%! clf;
%! t1 = (1/16:1/8:1) * 2*pi;
%! t2 = ((1/16:1/8:1) + 1/32) * 2*pi;
%! x1 = sin (t1) - 0.8;
%! y1 = cos (t1);
%! z1 = sin (t1);
%! x2 = sin (t2) + 0.8;
%! y2 = cos (t2);
%! z2 = sin (t2);
%! h = fill3 (x1,y1,z1,"r", x2,y2,z2,"g");
%! title ({"fill3() function"; "cdata specified with string"});
%! grid ("on");

%!demo
%! clf;
%! t1 = (1/16:1/8:1) * 2*pi;
%! t2 = ((1/16:1/8:1) + 1/32) * 2*pi;
%! x1 = sin (t1) - 0.8;
%! y1 = cos (t1);
%! z1 = sin (t1);
%! x2 = sin (t2) + 0.8;
%! y2 = cos (t2);
%! z2 = sin (t2);
%! h = fill3 (x1,y1,z1,1, x2,y2,z2,2);
%! title ({"fill3() function"; 'cdata = row vector produces FaceColor = "flat"'});
%! grid ("on");

%!demo
%! clf;
%! x = [0 0
%!      1 0.5
%!      1 0.5
%!      0 0];
%! y = [0 0
%!      0 0
%!      1 0.5
%!      1 0.5];
%! z = y;
%! z(:,2) += 1e-4;
%! c = [1 2 3 4]';
%! fill3 (x, y, z, [c c]);
%! title ({"fill3() function"; 'cdata = column vector produces FaceColor = "interp"'});
%! grid ("on");