splitPolygons(polygon)

function polygons = splitPolygons(polygon)
%SPLITPOLYGONS Convert a NaN separated polygon list to a cell array of polygons
%
%   POLYGONS = splitPolygons(POLYGON);
%   POLYGON is a N*2 array of points, with possibly couples of NaN values.
%   The functions separates each component separated by NaN values, and
%   returns a cell array of polygons.
%
%   See also:
%   polygons2d
%
% ------
% Author: David Legland
% e-mail: [e-mail]
% Created: 2007-10-12,    using Matlab 7.4.0.287 (R2007a)
% Copyright 2007 INRA - BIA PV Nantes - MIAJ Jouy-en-Josas.

if iscell(polygon)
    % case of a cell array
    polygons = polygon;
    
elseif sum(isnan(polygon(:)))==0
    % single polygon -> no break
    polygons = {polygon};
    
else
    % find indices of NaN couples
    inds = find(sum(isnan(polygon), 2)>0);
    
    % number of polygons
    N = length(inds)+1;
    polygons = cell(N, 1);

    % iterate over NaN-separated regions to create new polygon
    inds = [0;inds;size(polygon, 1)+1];
    for i=1:N
        polygons{i} = polygon((inds(i)+1):(inds(i+1)-1), :);    
    end
end