source: liacs/la/opdr3/rotate.m@ 400

function B = rotate(A,degrees)
    % With a litle help of
    % http://www.mathworks.com/matlabcentral/
    % fileexchange/loadFile.do?objectId=4071
    %
    % bepaal dimentie
    B = A;
    degrees_rad = degrees * pi / 180;
    %rotatiematrix
    R = [ cos(degrees_rad), sin(degrees_rad), 0;
          sin(-degrees_rad), cos(degrees_rad), 0;
          0, 0, 1];
    %bepaal buitenzijden en midden
    [in_size_x, in_size_y] = size(A);
    in_mid_x = ( in_size_x-1) / 2;
    in_mid_y = ( in_size_y-1) / 2;
    %max grootte van het nieuwe plaatje is de helft de diameter
    % en dan 'rechtop'
    dia = int64(sqrt(in_size_x^2  + in_size_y^2 ));
    B = zeros([dia,dia]);
    %grootte van de nieuwe matrix
    [out_size_x, out_size_y] = size(B);
    out_mid_x = ( out_size_x-1) / 2;
    out_mid_y = ( out_size_y-1) / 2;
    %
    %translatiematrix
    Tout = [ 1, 0, out_mid_x;
             0, 1, out_mid_y;
             0, 0, 1;];
    Tin = [ 1, 0, -in_mid_x;
            0, 1, -in_mid_y;
            0, 0, 1; ];
    Trans = Tout * R * Tin;
    % Laten we maar gaan draaien ;-)
    for i=1:in_size_x
        for j=1:in_size_y
            out = round(Trans * [i;j;1;]);
            %gegevens overhevelen
            B(out(1),out(2)) = A(i,j);
        end
    end