Add a useful package (from Source forge) for octave

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

diff --git a/octave_packages/geometry-1.5.0/geom2d/ellipseAsPolygon.m b/octave_packages/geometry-1.5.0/geom2d/ellipseAsPolygon.m
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+++ b/octave_packages/geometry-1.5.0/geom2d/ellipseAsPolygon.m
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+%% Copyright (c) 2011, INRA
+%% 2004-2011, 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{p} = } ellipseAsPolygon (@var{ell}, @var{n})
+%% Convert an ellipse into a series of points
+%%
+%%   P = ellipseAsPolygon(ELL, N);
+%%   converts ELL given as [x0 y0 a b] or [x0 y0 a b theta] into a polygon
+%%   with N edges. The result P is (N+1)-by-2 array containing coordinates
+%%   of the N+1 vertices of the polygon.
+%%   The resulting polygon is closed, i.e. the last point is the same as the
+%%   first one.
+%%
+%%   P = ellipseAsPolygon(ELL);
+%%   Use a default number of edges equal to 72. This result in one piont for
+%%   each 5 degrees.
+%%   
+%%   [X Y] = ellipseAsPolygon(...);
+%%   Return the coordinates o fvertices in two separate arrays.
+%%
+%%   @seealso{ellipses2d, circleAsPolygon, rectAsPolygon, drawEllipse}
+%% @end deftypefn
+
+function varargout = ellipseAsPolygon(ellipse, N)
+
+  % default value for N
+  if nargin < 2
+      N = 72;
+  end
+
+  % angle of ellipse
+  theta = 0;
+  if size(ellipse, 2) > 4
+      theta = ellipse(:,5);
+  end
+
+  % get ellipse parameters
+  xc = ellipse(:,1);
+  yc = ellipse(:,2);
+  a  = ellipse(:,3);
+  b  = ellipse(:,4);
+
+  % create time basis
+  t = linspace(0, 2*pi, N+1)';
+
+  % pre-compute trig functions (angles is in degrees)
+  cot = cosd(theta);
+  sit = sind(theta);
+
+  % position of points
+  x = xc + a * cos(t) * cot - b * sin(t) * sit;
+  y = yc + a * cos(t) * sit + b * sin(t) * cot;
+
+  % format output depending on number of a param.
+  if nargout == 1
+      varargout = {[x y]};
+  elseif nargout == 2
+      varargout = {x, y};
+  end
+
+endfunction
+