Add a useful package (from Source forge) for octave

[CreaPhase.git] / octave_packages / geometry-1.5.0 / geom2d / projPointOnLine.m

diff --git a/octave_packages/geometry-1.5.0/geom2d/projPointOnLine.m b/octave_packages/geometry-1.5.0/geom2d/projPointOnLine.m
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+++ b/octave_packages/geometry-1.5.0/geom2d/projPointOnLine.m
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+%% Copyright (c) 2011, INRA
+%% 2005-2011, David Legland <david.legland@grignon.inra.fr>
+%% 2011 Adapted to Octave by Juan Pablo Carbajal <carbajal@ifi.uzh.ch>
+%%
+%% All rights reserved.
+%% (simplified BSD License)
+%%
+%% 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"
+%% AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+%% IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+%% ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+%% LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 
+%% CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+%% SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 
+%% INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+%% CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+%% ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+%% POSSIBILITY OF SUCH DAMAGE.
+%%
+%% The views and conclusions contained in the software and documentation are
+%% those of the authors and should not be interpreted as representing official
+%% policies, either expressed or implied, of copyright holder.
+
+%% -*- texinfo -*-
+%% @deftypefn {Function File} {@var{point} = } projPointOnLine (@var{pt1}, @var{line})
+%%  Project of a point orthogonally onto a line
+%%
+%%   Computes the (orthogonal) projection of point @var{pt1} onto the line @var{line}.
+%%   
+%%   Function works also for multiple points and lines. In this case, it
+%%   returns multiple points.
+%%   Point @var{pt1} is a [N*2] array, and @var{line} is a [N*4] array (see createLine
+%%   for details). Result @var{point} is a [N*2] array, containing coordinates of
+%%   orthogonal projections of @var{pt1} onto lines @var{line}.
+%%
+%%   @seealso{lines2d, points2d, isPointOnLine, linePosition}
+%% @end deftypefn
+
+function point = projPointOnLine(point, line)
+
+  % ensure input arguments have same size
+  if size(line, 1)==1 && size(point, 1)>1
+      line = repmat(line, [size(point, 1) 1]);
+  end
+  if size(point, 1)==1 && size(line, 1)>1
+      point = repmat(point, [size(line, 1) 1]);
+  end
+
+  % slope of line
+  dx = line(:, 3);
+  dy = line(:, 4);
+
+  % first find relative position of projection on the line,
+  tp = ((point(:, 2) - line(:, 2)).*dy + (point(:, 1) - line(:, 1)).*dx) ./ (dx.*dx+dy.*dy);
+
+  % convert position on line to cartesian coordinate
+  point = line(:,1:2) + [tp tp].*[dx dy];
+
+endfunction