Add a useful package (from Source forge) for octave

[CreaPhase.git] / octave_packages / geometry-1.5.0 / polygons2d / simplifypolygon.m

diff --git a/octave_packages/geometry-1.5.0/polygons2d/simplifypolygon.m b/octave_packages/geometry-1.5.0/polygons2d/simplifypolygon.m
new file mode 100644 (file)
index 0000000..5993cfc
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+++ b/octave_packages/geometry-1.5.0/polygons2d/simplifypolygon.m
@@ -0,0 +1,60 @@
+## Copyright (c) 2011 Juan Pablo Carbajal <carbajal@ifi.uzh.ch>
+##
+## This program is free software; you can redistribute it and/or modify
+## it under the terms of the GNU General Public License as published by
+## the Free Software Foundation; either version 3 of the License, or
+## (at your option) any later version.
+##
+## This program is distributed in the hope that it will be useful,
+## but WITHOUT ANY WARRANTY; without even the implied warranty of
+## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+## GNU General Public License for more details.
+##
+## You should have received a copy of the GNU General Public License
+## along with this program; if not, see <http://www.gnu.org/licenses/>.
+
+%% -*- texinfo -*-
+%% @deftypefn {Function File} {@var{spoly} = } simplifypolygon (@var{poly})
+%% Simplify a polygon using the Ramer-Douglas-Peucker algorithm.
+%%
+%% @var{poly} is a N-by-2 matrix, each row representing a vertex.
+%%
+%% @seealso{simplifypolyline, shape2polygon}
+%% @end deftypefn
+
+function polygonsimp = simplifypolygon (polygon, varargin)
+
+  polygonsimp = simplifypolyline (polygon,varargin{:});
+
+  # Remove parrallel consecutive edges
+  PL = polygonsimp(1:end-1,:);
+  PC = polygonsimp(2:end,:);
+  PR = polygonsimp([3:end 1],:);
+  a = PL - PC;
+  b = PR - PC;
+  tf = find(isParallel(a,b))+1;
+  polygonsimp (tf,:) = [];
+
+endfunction
+
+%!test
+%!  P = [0 0; 1 0; 0 1];
+%!  P2 = [0 0; 0.1 0; 0.2 0; 0.25 0; 1 0; 0 1; 0 0.7; 0 0.6; 0 0.3; 0 0.1];
+%! assert(simplifypolygon (P2),P,min(P2(:))*eps)
+
+%!demo
+%!
+%!  P = [0 0; 1 0; 0 1];
+%!  P2 = [0 0; 0.1 0; 0.2 0; 0.25 0; 1 0; 0 1; 0 0.7; 0 0.6; 0 0.3; 0 0.1];
+%!  Pr = simplifypolygon (P2);
+%!
+%!  cla
+%!  drawPolygon(P,'or;Reference;');
+%!  hold on
+%!  drawPolygon(P2,'x-b;Redundant;');
+%!  drawPolygon(Pr,'*g;Simplified;');
+%!  hold off
+%!
+%! % --------------------------------------------------------------------------
+%! % The two polygons describe the same figure, a triangle. Extra points are
+%! % removed form the redundant one.