polygonBounds

 Computes the bounding box of a polygon.

   BOX = polygonBounds(POLY);
   Returns the bounding box of the polygon. 
   BOX has the format: [XMIN XMAX YMIN YMAX].

   Input polygon POLY is as a N-by-2 array containing coordinates of each
   vertex. 
   Multiple polygons can be specified either by inserting NaN rows between
   vertex coordinates, or by using a cell array, each cell containing the
   vertex coordinates of a polygon loop. 

   See also
   polygons2d, boxes2d, boundingBox

0001 function box = polygonBounds(polygon)
0002 % Computes the bounding box of a polygon.
0003 %
0004 %   BOX = polygonBounds(POLY);
0005 %   Returns the bounding box of the polygon.
0006 %   BOX has the format: [XMIN XMAX YMIN YMAX].
0007 %
0008 %   Input polygon POLY is as a N-by-2 array containing coordinates of each
0009 %   vertex.
0010 %   Multiple polygons can be specified either by inserting NaN rows between
0011 %   vertex coordinates, or by using a cell array, each cell containing the
0012 %   vertex coordinates of a polygon loop.
0013 %
0014 %   See also
0015 %   polygons2d, boxes2d, boundingBox
0016 %
0017 
0018 % ------
0019 % Author: David Legland
0020 % e-mail: david.legland@inrae.fr
0021 % Created: 2007-10-12,    using Matlab 7.4.0.287 (R2007a)
0022 % Copyright 2007 INRA - Cepia software platform
0023 
0024 
0025 % transform as a cell array of simple polygons
0026 polygons = splitPolygons(polygon);
0027 
0028 % init extreme values
0029 xmin = inf;
0030 xmax = -inf;
0031 ymin = inf;
0032 ymax = -inf;
0033 
0034 % iterate over loops
0035 for i = 1:length(polygons)
0036     polygon = polygons{i};
0037     
0038     xmin = min(xmin, min(polygon(:,1)));
0039     xmax = max(xmax, max(polygon(:,1)));
0040     ymin = min(ymin, min(polygon(:,2)));
0041     ymax = max(ymax, max(polygon(:,2)));
0042 end
0043 
0044 % format output
0045 box = [xmin xmax ymin ymax];