## Copyright (C) 2015,2016 Philip Nienhuis ## ## 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 . ## -*- texinfo -*- ## @deftypefn {Function File} [@var{orientation}] = isPolygonCW_Clipper (@var{inpol}) ## Inspect winding direction of polygon(s). ## ## Based on Clipper library, polyclipping.sf.net, 3rd Party, Matlab ## ## @var{inpol} = Nx2 matrix of (X, Y) coordinates constituting the polygons(s) ## whose winding direction should be assessed. Subpolygons are separated by ## [NaN NaN] rows. ## ## Output argument @var{orientation} indicates the winding direction(s) of ## each subpolygon: 0 for clockwise, 1 for counterclockwise. ## ## @end deftypefn ## Author: Philip Nienhuis ## Created: 2015-05-03 ## Based on Clipper library, polyclipping.sf.net, 3rd Party, Matlab function [orientation] = isPolygonCW_Clipper (inpoly) ## Input validation if (nargin < 1) print_usage (); endif if (! isnumeric (inpoly) || size (inpoly, 2) < 2) error ("ispolycw: inpoly should be a numeric Nx2 array"); endif ## Convert & scale to int64 (that's what Clipper works with) ## Find (X, Y) translation xy_mean = mean (inpoly(isfinite (inpoly(:, 1)), :)); ## Find (X, Y) magnitude xy_magn = max (inpoly(isfinite (inpoly(:, 1)), :)) ... - min (inpoly(isfinite (inpoly(:, 1)), :)); ## Apply (X,Y) multiplication (floor (log10 (intmax ("int64"))) = 18) xy_magn = 10^(17 - ceil (max (log10 (xy_magn)))); ## Scale inpoly coordinates to optimally use int64 inpoly(:, 1:2) -= xy_mean; inpoly *= xy_magn; idin = [ 0 find(isnan (inpoly (:, 1)))' numel(inpoly (:, 1))+1 ]; for ii=1:numel (idin) - 1 inpol(ii).x = int64 (inpoly(idin(ii)+1:idin(ii+1)-1, 1)); inpol(ii).y = int64 (inpoly(idin(ii)+1:idin(ii+1)-1, 2)); endfor ## Just find out orientation of polygons orientation = clipper (inpol); endfunction