rowToPolygon

ROWTOPOLYGON  Create a polygon from a row vector.

   POLY = rowToPolygon(ROW)
   Convert a 1-by-2*N row vector that concatenates all polygon vertex
   coordinates into a N-by-2 array of coordinates.
   Default ordering of coordinates in ROW is:
   [X1 Y1 X2 Y2 X3 Y3 .... XN YN].

   POLY = rowToPolygon(ROW, METHOD)
   Specifies the method for concatenating coordinates. METHOS is one of:
   'interlaced': default method, described above.
   'packed': the vector ROW has format:
   [X1 X2 X3 ... XN Y1 Y2 Y3 ... YN].

   POLYS = rowToPolygon(ROWS, ...)
   When ROWS is a NP-by-NV array containing the vertex coordinates of NP
   polygons, returns a 1-by-NP cell array containing in each cell the
   coordinates of the polygon.


   Example
   % Concatenate coordinates of a circle and draw it as a polygon
     t = linspace (0, 2*pi, 200);
     row = [cos(t) sin(t)];
     poly = rowToPolygon(row, 'packed');
     figure;drawPolygon(poly)

   See also
   polygons2d, polygonToRow

0001 function poly = rowToPolygon(row, varargin)
0002 %ROWTOPOLYGON  Create a polygon from a row vector.
0003 %
0004 %   POLY = rowToPolygon(ROW)
0005 %   Convert a 1-by-2*N row vector that concatenates all polygon vertex
0006 %   coordinates into a N-by-2 array of coordinates.
0007 %   Default ordering of coordinates in ROW is:
0008 %   [X1 Y1 X2 Y2 X3 Y3 .... XN YN].
0009 %
0010 %   POLY = rowToPolygon(ROW, METHOD)
0011 %   Specifies the method for concatenating coordinates. METHOS is one of:
0012 %   'interlaced': default method, described above.
0013 %   'packed': the vector ROW has format:
0014 %   [X1 X2 X3 ... XN Y1 Y2 Y3 ... YN].
0015 %
0016 %   POLYS = rowToPolygon(ROWS, ...)
0017 %   When ROWS is a NP-by-NV array containing the vertex coordinates of NP
0018 %   polygons, returns a 1-by-NP cell array containing in each cell the
0019 %   coordinates of the polygon.
0020 %
0021 %
0022 %   Example
0023 %   % Concatenate coordinates of a circle and draw it as a polygon
0024 %     t = linspace (0, 2*pi, 200);
0025 %     row = [cos(t) sin(t)];
0026 %     poly = rowToPolygon(row, 'packed');
0027 %     figure;drawPolygon(poly)
0028 %
0029 %   See also
0030 %   polygons2d, polygonToRow
0031 
0032 % ------
0033 % Author: David Legland
0034 % e-mail: david.legland@grignon.inra.fr
0035 % Created: 2010-07-23,    using Matlab 7.9.0.529 (R2009b)
0036 % Copyright 2010 INRA - Cepia Software Platform.
0037 
0038 %   HISTORY
0039 %   2014-01-29 add support for multiple rows
0040 
0041 type = 'interlaced';
0042 if ~isempty(varargin)
0043     type = varargin{1};
0044 end
0045 
0046 % number of polygons
0047 nPolys = size(row, 1);
0048     
0049 % polygon vertex number
0050 Np = size(row, 2) / 2;
0051 
0052 
0053 if strcmp(type, 'interlaced')
0054     % ordering is [X1 Y1 X2 X2... XN YN]
0055     if nPolys == 1
0056         poly = reshape(row, [2 Np])';
0057     else
0058         poly = cell(1, nPolys);
0059         for i = 1:nPolys
0060             poly{i} = reshape(row(i,:), [2 Np])';
0061         end
0062     end
0063     
0064 elseif strcmp(type, 'packed')
0065     % ordering is [X1 X2 X3... XN Y1 Y2 Y3... YN]
0066     if nPolys == 1
0067         poly = [row(1:Np)' row(Np+1:end)'];
0068     else
0069         poly = cell(1, nPolys);
0070         for i = 1:nPolys
0071             poly{i} = [row(i, 1:Np)' row(i, Np+1:end)'];
0072         end
0073     end
0074 end