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geom2d

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geom2d

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13 Jun 2005 (Updated )

Geometry library for matlab. Performs geometric computations on points, lines, circles, polygons...

rowToPolygon(row, varargin)
function poly = rowToPolygon(row, varargin)
%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

% ------
% Author: David Legland
% e-mail: david.legland@grignon.inra.fr
% Created: 2010-07-23,    using Matlab 7.9.0.529 (R2009b)
% Copyright 2010 INRA - Cepia Software Platform.

%   HISTORY
%   2014-01-29 add support for multiple rows

type = 'interlaced';
if ~isempty(varargin)
    type = varargin{1};
end

% number of polygons
nPolys = size(row, 1);
    
% polygon vertex number
Np = size(row, 2) / 2;


if strcmp(type, 'interlaced')
    % ordering is [X1 Y1 X2 X2... XN YN]
    if nPolys == 1
        poly = reshape(row, [2 Np])';
    else
        poly = cell(1, nPolys);
        for i = 1:nPolys
            poly{i} = reshape(row(i,:), [2 Np])';
        end
    end
    
elseif strcmp(type, 'packed')
    % ordering is [X1 X2 X3... XN Y1 Y2 Y3... YN]
    if nPolys == 1
        poly = [row(1:Np)' row(Np+1:end)'];
    else
        poly = cell(1, nPolys);
        for i = 1:nPolys
            poly{i} = [row(i, 1:Np)' row(i, Np+1:end)'];
        end
    end
end

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