polygonVertices

POLYGONVERTICES Extract all vertices of a (multi-)polygon.

   VERTS = polygonVertices(POLY)
   Returns the set of verttices from the polygon POLY. POLY can be either:
   * a N-by-2 array of vertices. In that case, POLY and VERTS are the
       same.
   * a N-by-2 array of vertices with pairs of NaN values separating two
       rings of the polygon. In that case, the array VERTS corresponds to
       the vertices of the polygon, without copying the NaN values.
   * a cell array of loops. In that case, the functions recursively
       process the polygons and populated the vertex array.


   Example
     % create a polygon with a hole, using NaN for separating rings
     ring1 = [0 0 ; 50 0;50 50;0 50];
     ring2 = [20 20;20 30;30 30;30 20];
     poly = [ring1 ; NaN NaN ; ring2];
     figure; drawPolygon(poly, 'b'); 
     axis([-10 60 -10 60]); axis equal; hold on;
     verts = polygonVertices(poly);
     drawPoint(verts, 'bo');

     % create a polygon with a hole, storing rings in cell array
     ring1 = [0 0 ; 50 0;50 50;0 50];
     ring2 = [20 20;20 30;30 30;30 20];
     poly = {ring1, ring2};
     figure; drawPolygon(poly, 'b'); 
     axis([-10 60 -10 60]); axis equal; hold on;
     verts = polygonVertices(poly);
     drawPoint(verts, 'bo');

   See also
     polygons2d, polygonEdges

0001 function vertices = polygonVertices(poly)
0002 %POLYGONVERTICES Extract all vertices of a (multi-)polygon.
0003 %
0004 %   VERTS = polygonVertices(POLY)
0005 %   Returns the set of verttices from the polygon POLY. POLY can be either:
0006 %   * a N-by-2 array of vertices. In that case, POLY and VERTS are the
0007 %       same.
0008 %   * a N-by-2 array of vertices with pairs of NaN values separating two
0009 %       rings of the polygon. In that case, the array VERTS corresponds to
0010 %       the vertices of the polygon, without copying the NaN values.
0011 %   * a cell array of loops. In that case, the functions recursively
0012 %       process the polygons and populated the vertex array.
0013 %
0014 %
0015 %   Example
0016 %     % create a polygon with a hole, using NaN for separating rings
0017 %     ring1 = [0 0 ; 50 0;50 50;0 50];
0018 %     ring2 = [20 20;20 30;30 30;30 20];
0019 %     poly = [ring1 ; NaN NaN ; ring2];
0020 %     figure; drawPolygon(poly, 'b');
0021 %     axis([-10 60 -10 60]); axis equal; hold on;
0022 %     verts = polygonVertices(poly);
0023 %     drawPoint(verts, 'bo');
0024 %
0025 %     % create a polygon with a hole, storing rings in cell array
0026 %     ring1 = [0 0 ; 50 0;50 50;0 50];
0027 %     ring2 = [20 20;20 30;30 30;30 20];
0028 %     poly = {ring1, ring2};
0029 %     figure; drawPolygon(poly, 'b');
0030 %     axis([-10 60 -10 60]); axis equal; hold on;
0031 %     verts = polygonVertices(poly);
0032 %     drawPoint(verts, 'bo');
0033 %
0034 %   See also
0035 %     polygons2d, polygonEdges
0036 
0037 % ------
0038 % Author: David Legland
0039 % E-mail: david.legland@inrae.fr
0040 % Created: 2018-06-07, using Matlab 9.4.0.813654 (R2018a)
0041 % Copyright 2018-2024 INRA - Cepia Software Platform
0042 
0043 if isnumeric(poly)
0044     % find NaN or infinite values
0045     inds = sum(isfinite(poly), 2) == 2;
0046     
0047     % filter non-finite vertices if necessary
0048     if any(~inds)
0049         vertices = poly(inds, :);
0050     else
0051         vertices = poly;
0052     end
0053 elseif iscell(poly)
0054     % process cell array
0055     vertices = zeros(0, 2);
0056     for i = 1:length(poly)
0057         vertices = [vertices ; polygonVertices(poly{i})]; %#ok<AGROW>
0058     end
0059 end