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%BRESENHAM Generate a line
%
% P = BRESENHAM(X1, Y1, X2, Y2) is a list of integer coordinates for
% points lying on the line segement (X1,Y1) to (X2,Y2). Endpoints
% must be integer.
%
% P = BRESENHAM(P1, P2) as above but P1=[X1,Y1] and P2=[X2,Y2].
%
% See also ICANVAS.
% Copyright (C) 1993-2011, by Peter I. Corke
%
% This file is part of The Machine Vision Toolbox for Matlab (MVTB).
%
% MVTB is free software: you can redistribute it and/or modify
% it under the terms of the GNU Lesser General Public License as published by
% the Free Software Foundation, either version 3 of the License, or
% (at your option) any later version.
%
% MVTB is distributed in the hope that it will be useful,
% but WITHOUT ANY WARRANTY; without even the implied warranty of
% MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
% GNU Lesser General Public License for more details.
%
% You should have received a copy of the GNU Leser General Public License
% along with MVTB. If not, see <http://www.gnu.org/licenses/>.
function p = bresenham(x1, y1, x2, y2)
if nargin == 2
p1 = x1; p2 = y1;
x1 = p1(1); y1 = p1(2);
x2 = p2(1); y2 = p2(2);
elseif nargin ~= 4
error('expecting 2 or 4 arguments');
end
x = x1;
if x2 > x1
xd = x2-x1;
dx = 1;
else
xd = x1-x2;
dx = -1;
end
y = y1;
if y2 > y1
yd = y2-y1;
dy = 1;
else
yd = y1-y2;
dy = -1;
end
p = [];
if xd > yd
a = 2*yd;
b = a - xd;
c = b - xd;
while 1
p = [p; x y];
if all([x-x2 y-y2] == 0)
break
end
if b < 0
b = b+a;
x = x+dx;
else
b = b+c;
x = x+dx; y = y+dy;
end
end
else
a = 2*xd;
b = a - yd;
c = b - yd;
while 1
p = [p; x y];
if all([x-x2 y-y2] == 0)
break
end
if b < 0
b = b+a;
y = y+dy;
else
b = b+c;
x = x+dx; y = y+dy;
end
end
end
end