Add a useful package (from Source forge) for octave

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

diff --git a/octave_packages/geometry-1.5.0/geom2d/closed_path.m b/octave_packages/geometry-1.5.0/geom2d/closed_path.m
new file mode 100644 (file)
index 0000000..4ea3839
--- /dev/null
+++ b/octave_packages/geometry-1.5.0/geom2d/closed_path.m
@@ -0,0 +1,105 @@
+%% Copyright (C) 2012 Simeon Simeonov <simeon.simeonov.s@gmail.com>
+%%
+%%    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
+%%    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{y} =} polygon (@var{x})
+%% Returns a simple closed path that passes through all the points in @var{x}.
+%% @var{x} is a vector containing 2D coordinates of the points.
+%%
+%% @end deftypefn
+
+%% Author: Simeon Simeonov <simeon.simeonov.s@gmail.com>
+
+function y = closed_path(x)
+
+  if(size(x,1) > 1 && size(x,1) < size(x,2))
+      x = x';
+  end
+
+  N = size(x,1); % Number of points
+  idx = zeros(N, 1); % ind contains the indices of the sorted coordinates
+
+  a = find(x(:,2)==min(x(:,2)));
+
+  if(size(a,1) > 1)
+      [~, i] = sort(x(a,1));
+      a = a(i(1));
+  end
+
+  x_1 = x(x(:,2)==x(a,2),:); % find all x with the same y coordinate
+
+  if(x(a,1) == min(x(:,1)))
+      x_2 = x(x(:,1)==x(a,1),:); % find all x with the same x coordinate
+  else
+     x_2 = x(a,:);
+  end
+
+  if(size(x_1,1) > 1 || size(x_2,1) > 1)
+      if(size(x_1,1) > 1)
+          x_1 = sort(x_1); % Sort by x coordinate
+          y(1,:) = x(a,:); % original starting point
+      end
+
+      if (size(x_2,1) > 1)
+          x_2 = sort(x_2, 'descend');
+      end
+
+      x_not = [x_1; x_2];
+      i = ismember(x,x_not,'rows');
+      x(i, :) = [];
+      x = [x_1(size(x_1,1),:); x];
+      x_1(size(x_1, 1),:) = [];
+      N = size(x,1);
+      a = 1;
+  else
+      x_1 = [];
+      x_2 = x(a,:);
+  end
+  d = x - repmat(x(a,:), N, 1);
+  th = d(:,2)./(d(:,1) + d(:,2));
+
+  [~, idx0] = ismember(sort(th(th==0)), th);
+  [~, idx1] = ismember(sort(th(th>0)), th);
+  [~, idx2] = ismember(sort(th(th<0)), th);
+
+  idx = [a; idx0; idx1; idx2];
+  % I contains the indices of idx in a sorted order. [v i] = sort(idx) then
+  % i==I.
+  [~,I,J]= unique(idx);
+  if(size(I,1) ~= size(J,1))
+      R = histc(J, 1:size(I,1)); % R(1) will always be 1?
+      idx_sorted = idx(I);
+      r = find(R>1);
+      for ri = r'
+          idx_repeated = idx_sorted(ri);
+          idx(idx==idx_repeated) = find(th==th(idx_sorted(ri)));
+      end
+  end
+
+  y = [x_1; x(idx,:); x_2;];
+
+endfunction
+
+%!demo
+%! maxInt = 100;
+%! N = 25;
+%!
+%! for i = 1:5
+%!   x = randi(maxInt, N, 2);
+%!   y = closed_path(x);
+%!   plot(y(:,1), y(:,2), '*');
+%!   hold on;
+%!   plot(y(:,1), y(:,2));
+%! end