/usr/share/octave/packages/geometry-1.7.0/polygons2d/polygonLoops.m is in octave-geometry 1.7.0-1build1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 | ## Copyright (C) 2004-2011 David Legland <david.legland@grignon.inra.fr>
## Copyright (C) 2004-2011 INRA - CEPIA Nantes - MIAJ (Jouy-en-Josas)
## Copyright (C) 2012 Adapted to Octave by Juan Pablo Carbajal <carbajal@ifi.uzh.ch>
## All rights reserved.
##
## 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 AUTHOR 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.
## -*- texinfo -*-
## @deftypefn {Function File} {@var{loops} = } polygonLoops (@var{poly})
## Divide a possibly self-intersecting polygon into a set of simple loops
##
## @var{poly} is a polygone defined by a series of vertices,
## @var{loops} is a cell array of polygons, containing the same vertices of the
## original polygon, but no loop self-intersect, and no couple of loops
## intersect each other.
##
## Example:
## @example
## poly = [0 0;0 10;20 10;20 20;10 20;10 0];
## loops = polygonLoops(poly);
## figure(1); hold on;
## drawPolygon(loops);
## polygonArea(loops)
## @end example
##
## @seealso{polygons2d, polygonSelfIntersections}
## @end deftypefn
function loops = polygonLoops(poly)
## Initialisations
# compute intersections
[inters pos1 pos2] = polygonSelfIntersections(poly);
# case of a polygon without self-intersection
if isempty(inters)
loops = {poly};
return;
end
# array for storing loops
loops = cell(0, 1);
positions = sortrows([pos1 pos2;pos2 pos1]);
## First loop
pos0 = 0;
loop = polygonSubcurve(poly, pos0, positions(1, 1));
pos = positions(1, 2);
positions(1, :) = [];
while true
# index of next intersection point
ind = find(positions(:,1)>pos, 1, 'first');
# if not found, break
if isempty(ind)
break;
end
# add portion of curve
loop = [loop; polygonSubcurve(poly, pos, positions(ind, 1))]; ##ok<AGROW>
# look for next intersection point
pos = positions(ind, 2);
positions(ind, :) = [];
end
# add the last portion of curve
loop = [loop;polygonSubcurve(poly, pos, pos0)];
# remove redundant vertices
loop(sum(loop(1:end-1,:) == loop(2:end,:) ,2)==2, :) = [];
if sum(diff(loop([1 end], :))==0)==2
loop(end, :) = [];
end
# add current loop to the list of loops
loops{1} = loop;
## Other loops
Nl = 1;
while ~isempty(positions)
loop = [];
pos0 = positions(1, 2);
pos = positions(1, 2);
while true
# index of next intersection point
ind = find(positions(:,1)>pos, 1, 'first');
# add portion of curve
loop = [loop;polygonSubcurve(poly, pos, positions(ind, 1))]; ##ok<AGROW>
# look for next intersection point
pos = positions(ind, 2);
positions(ind, :) = [];
# if not found, break
if pos==pos0
break;
end
end
# remove redundant vertices
loop(sum(loop(1:end-1,:) == loop(2:end,:) ,2)==2, :) = []; ##ok<AGROW>
if sum(diff(loop([1 end], :))==0)==2
loop(end, :) = []; ##ok<AGROW>
end
# add current loop to the list of loops
Nl = Nl + 1;
loops{Nl} = loop;
end
endfunction
|