removeMultipleVertices

REMOVEMULTIPLEVERTICES Remove multiple vertices of a polygon or polyline.

   POLY2 = removeMultipleVertices(POLY, EPS)
   Remove adjacent vertices that are closer than the distance EPS to each
   other and merge them to a unique vertex.

   POLY2 = removeMultipleVertices(POLY, EPS, CLOSED)
   If CLOSED is true, also check if first and last vertices need to be
   merged. If not specified, CLOSED is false.

   Example
     poly = [10 10; 20 10;20 10;20 20;10 20; 10 10];
     poly2 = removeMultipleVertices(poly, true);
     size(poly2, 1)
     ans = 
         4

   See also
   polygons2d, mergeClosePoints

0001 function poly = removeMultipleVertices(poly, varargin)
0002 %REMOVEMULTIPLEVERTICES Remove multiple vertices of a polygon or polyline.
0003 %
0004 %   POLY2 = removeMultipleVertices(POLY, EPS)
0005 %   Remove adjacent vertices that are closer than the distance EPS to each
0006 %   other and merge them to a unique vertex.
0007 %
0008 %   POLY2 = removeMultipleVertices(POLY, EPS, CLOSED)
0009 %   If CLOSED is true, also check if first and last vertices need to be
0010 %   merged. If not specified, CLOSED is false.
0011 %
0012 %   Example
0013 %     poly = [10 10; 20 10;20 10;20 20;10 20; 10 10];
0014 %     poly2 = removeMultipleVertices(poly, true);
0015 %     size(poly2, 1)
0016 %     ans =
0017 %         4
0018 %
0019 %   See also
0020 %   polygons2d, mergeClosePoints
0021 
0022 % ------
0023 % Author: David Legland
0024 % e-mail: david.legland@grignon.inra.fr
0025 % Created: 2013-10-04,    using Matlab 7.9.0.529 (R2009b)
0026 % Copyright 2013 INRA - Cepia Software Platform.
0027 
0028 % default values
0029 eps = 1e-14;
0030 closed = false;
0031 
0032 % process input options
0033 while ~isempty(varargin)
0034     var = varargin{1};
0035     if islogical(var)
0036         closed = var;
0037     elseif isnumeric(var)
0038         eps = var;
0039     else
0040         error('MatGeom:removeMultipleVertices:IllegalArgument',...
0041             'Can not interpret optional argument');
0042     end
0043     varargin(1) = [];
0044 end
0045 
0046 % distance between adjacent vertices
0047 dist = sqrt(sum((poly(2:end,:) - poly(1:end-1,:)).^2, 2));
0048 multi = dist < eps;
0049 
0050 % process extremities
0051 if closed
0052     dist = sqrt(sum((poly(end,:) - poly(1,:)).^2, 2));
0053     multi = [multi ; dist < eps];
0054 else
0055     multi = [multi ; false];
0056 end
0057 
0058 % remove multiple vertices
0059 poly(multi, :) = [];
0060