orientedBoxToPolygon

ORIENTEDBOXTOPOLYGON Convert an oriented box to a polygon (set of vertices).

   POLY = orientedBoxToPolygon(OBOX);
   Converts the oriented box OBOX given either as [XC YC W H] or as 
   [XC YC W H THETA] into a 4-by-2 array of double, containing coordinates
   of box vertices. 
   XC and YC are center of the box. W and H are the width and the height
   (dimension in the main directions), and THETA is the orientation, in
   degrees between 0 and 360.

   Example
     OBOX = [20 10  40 20 0];
     RECT = orientedBoxToPolygon(OBOX)
     RECT =
         -20 -10 
          20 -10 
          20  10 
         -20  10 


   See also:
   polygons2d, orientedBox, drawOrientedBox, rectToPolygon

0001 function [tx, ty] = orientedBoxToPolygon(obox)
0002 %ORIENTEDBOXTOPOLYGON Convert an oriented box to a polygon (set of vertices).
0003 %
0004 %   POLY = orientedBoxToPolygon(OBOX);
0005 %   Converts the oriented box OBOX given either as [XC YC W H] or as
0006 %   [XC YC W H THETA] into a 4-by-2 array of double, containing coordinates
0007 %   of box vertices.
0008 %   XC and YC are center of the box. W and H are the width and the height
0009 %   (dimension in the main directions), and THETA is the orientation, in
0010 %   degrees between 0 and 360.
0011 %
0012 %   Example
0013 %     OBOX = [20 10  40 20 0];
0014 %     RECT = orientedBoxToPolygon(OBOX)
0015 %     RECT =
0016 %         -20 -10
0017 %          20 -10
0018 %          20  10
0019 %         -20  10
0020 %
0021 %
0022 %   See also:
0023 %   polygons2d, orientedBox, drawOrientedBox, rectToPolygon
0024 %
0025 
0026 %   ---------
0027 % Author: David Legland
0028 % e-mail: david.legland@nantes.inra.fr
0029 % INRA - TPV URPOI - BIA IMASTE
0030 % created the 06/04/2005.
0031 %
0032 
0033 %   HISTORY
0034 %   2011-10-09 rewrite from rectAsPolygon to orientedBoxToPolygon
0035 %   2016: Simplify by JuanPi Carbajal
0036 
0037 % extract box parameters
0038 theta = 0;
0039 x = obox(1);
0040 y = obox(2);
0041 w = obox(3) / 2;  % easier to compute with w and h divided by 2
0042 h = obox(4) / 2;
0043 if length(obox) > 4
0044     theta = obox(5);
0045 end
0046 
0047 v = [cosd(theta); sind(theta)];
0048 M = bsxfun (@times, [-1 1; 1 1; 1 -1; -1 -1], [w h]);
0049 tx  = x + M * v;
0050 ty  = y + M(4:-1:1,[2 1]) * v;
0051 
0052 if nargout <= 1
0053   tx = [tx ty];
0054 end