## Copyright (C) 2004-2011 David Legland <david.legland@grignon.inra.fr>
## Copyright (C) 2004-2011 INRA - CEPIA Nantes - MIAJ (Jouy-en-Josas)
## Copyright (C) 2012 Adapted to Octave by Juan Pablo Carbajal <carbajal@ifi.uzh.ch>
## All rights reserved.
##
## Redistribution and use in source and binary forms, with or without
## modification, are permitted provided that the following conditions are met:
##
##     1 Redistributions of source code must retain the above copyright notice,
##       this list of conditions and the following disclaimer.
##     2 Redistributions in binary form must reproduce the above copyright
##       notice, this list of conditions and the following disclaimer in the
##       documentation and/or other materials provided with the distribution.
##
## THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS ''AS IS''
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## ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE FOR
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## -*- texinfo -*-
## @deftypefn {Function File} {@var{pt2} =} projPointOnPlane (@var{pt1}, @var{plane})
## Return the orthogonal projection of a point on a plane
##
##   PT2 = projPointOnPlane(PT1, PLANE);
##   Compute the (orthogonal) projection of point PT1 onto the line PLANE.
##
##   Function works also for multiple points and planes. In this case, it
##   returns multiple points.
##   Point PT1 is a [N*3] array, and PLANE is a [N*9] array (see createPlane
##   for details). Result PT2 is a [N*3] array, containing coordinates of
##   orthogonal projections of PT1 onto planes PLANE.
##
## @seealso{planes3d, points3d, planePosition, intersectLinePlane}
## @end deftypefn

function point = projPointOnPlane (point, plane)

  if size (point, 1) == 1
      point = repmat (point, [size(plane, 1) 1]);
  elseif size (plane, 1) == 1
      plane = repmat (plane, [size(point, 1) 1]);
  elseif size (plane, 1) ~= size (point, 1)
      error ('Octave:invalid-input-arg', ...
             'projPointOnPlane: size of inputs differ');
  end

  n     = planeNormal (plane);
  line  = [point n];
  point = intersectLinePlane (line, plane);

endfunction
