--- /dev/null
+%% Copyright (c) 2011, INRA
+%% 2010-2011, 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{ccw} = } isCounterClockwise (@var{p1}, @var{p2}, @var{p3})
+%% @deftypefnx {Function File} {@var{ccw} = } isCounterClockwise (@var{p1}, @var{p2}, @var{p3},@var{tol})
+%% Compute relative orientation of 3 points
+%%
+%% Computes the orientation of the 3 points. The returns is:
+%% +1 if the path @var{p1}-> @var{p2}-> @var{p3} turns Counter-Clockwise (i.e., the point @var{p3}
+%% is located "on the left" of the line @var{p1}- @var{p2})
+%% -1 if the path turns Clockwise (i.e., the point @var{p3} lies "on the right"
+%% of the line @var{p1}- @var{p2})
+%% 0 if the point @var{p3} is located on the line segment [ @var{p1} @var{p2}].
+%%
+%% This function can be used in more complicated algorithms: detection of
+%% line segment intersections, convex hulls, point in triangle...
+%%
+%% @var{ccw} = isCounterClockwise( @var{p1}, @var{p2}, @var{p3}, EPS);
+%% Specifies the threshold used for detecting colinearity of the 3 points.
+%% Default value is 1e-12 (absolute).
+%%
+%% Example
+%%
+%% @example
+%% isCounterClockwise([0 0], [10 0], [10 10])
+%% ans =
+%% 1
+%% isCounterClockwise([0 0], [0 10], [10 10])
+%% ans =
+%% -1
+%% isCounterClockwise([0 0], [10 0], [5 0])
+%% ans =
+%% 0
+%% @end example
+%%
+%% @seealso{points2d, isPointOnLine, isPointInTriangle}
+%% @end deftypefn
+
+function res = isCounterClockwise(p1, p2, p3, varargin)
+
+ % get threshold value
+ eps = 1e-12;
+ if ~isempty(varargin)
+ eps = varargin{1};
+ end
+
+ % ensure all data have same size
+ np = max([size(p1, 1) size(p2, 1) size(p3,1)]);
+ if np > 1
+ if size(p1,1) == 1
+ p1 = repmat(p1, np, 1);
+ end
+ if size(p2,1) == 1
+ p2 = repmat(p2, np, 1);
+ end
+ if size(p3,1) == 1
+ p3 = repmat(p3, np, 1);
+ end
+ end
+
+ % init with 0
+ res = zeros(np, 1);
+
+ % extract vector coordinates
+ x0 = p1(:, 1);
+ y0 = p1(:, 2);
+ dx1 = p2(:, 1) - x0;
+ dy1 = p2(:, 2) - y0;
+ dx2 = p3(:, 1) - x0;
+ dy2 = p3(:, 2) - y0;
+
+ % check non colinear cases
+ res(dx1 .* dy2 > dy1 .* dx2) = 1;
+ res(dx1 .* dy2 < dy1 .* dx2) = -1;
+
+ % case of colinear points
+ ind = abs(dx1 .* dy2 - dy1 .* dx2) < eps;
+ res(ind( (dx1(ind) .* dx2(ind) < 0) | (dy1(ind) .* dy2(ind) < 0) )) = -1;
+ res(ind( hypot(dx1(ind), dy1(ind)) < hypot(dx2(ind), dy2(ind)) )) = 1;
+
+endfunction
+
+%!shared p0,pu,pd,pl,pr
+%! p0 = [2, 3]; % center point
+%! pu = [2, 4]; % up point
+%! pd = [2, 2]; % down point
+%! pl = [1, 3]; % left point
+%! pr = [3, 3]; % right point
+
+%!assert (+1, isCounterClockwise(pl, p0, pu));
+%!assert (+1, isCounterClockwise(pd, p0, pl));
+%!assert (+1, isCounterClockwise(pr, p0, pd));
+%!assert (+1, isCounterClockwise(pu, p0, pr));
+
+% turn 90° right => return -1
+%!assert (-1, isCounterClockwise(pl, p0, pd));
+%!assert (-1, isCounterClockwise(pd, p0, pr));
+%!assert (-1, isCounterClockwise(pr, p0, pu));
+%!assert (-1, isCounterClockwise(pu, p0, pl));
+
+%!test % turn 90° left => return +1
+%! pts1 = [pl;pd;pr;pu;pl;pd;pr;pu];
+%! pts2 = [p0;p0;p0;p0;p0;p0;p0;p0];
+%! pts3 = [pu;pl;pd;pr;pd;pr;pu;pl];
+%! expected = [1;1;1;1;-1;-1;-1;-1];
+%! result = isCounterClockwise(pts1, pts2, pts3);
+%! assert (result, expected, 1e-6);
+
+% aligned with p0-p1-p2 => return +1
+%!assert (+1, isCounterClockwise(pl, p0, pr));
+%!assert (+1, isCounterClockwise(pu, p0, pd));
+%!assert (+1, isCounterClockwise(pr, p0, pl));
+%!assert (+1, isCounterClockwise(pd, p0, pu));
+
+% aligned ]ith p0-p2-p1 => return 0
+%!assert (0, isCounterClockwise(pl, pr, p0));
+%!assert (0, isCounterClockwise(pu, pd, p0));
+%!assert (0, isCounterClockwise(pr, pl, p0));
+%!assert (0, isCounterClockwise(pd, pu, p0));
+
+% aligned with p1-p0-p2 => return -1
+%!assert (-1, isCounterClockwise(p0, pl, pr));
+%!assert (-1, isCounterClockwise(p0, pu, pd));
+%!assert (-1, isCounterClockwise(p0, pr, pl));
+%!assert (-1, isCounterClockwise(p0, pr, pl));
git://git.creatis.insa-lyon.fr / CreaPhase.git / blobdiff