1## Copyright (C) 2021 David Legland
2## All rights reserved.
3##
4## Redistribution and use in source and binary forms, with or without
5## modification, are permitted provided that the following conditions are met:
6##
7##     1 Redistributions of source code must retain the above copyright notice,
8##       this list of conditions and the following disclaimer.
9##     2 Redistributions in binary form must reproduce the above copyright
10##       notice, this list of conditions and the following disclaimer in the
11##       documentation and/or other materials provided with the distribution.
12##
13## THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS ''AS IS''
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25## those of the authors and should not be interpreted as representing official
26## policies, either expressed or implied, of the copyright holders.
27
28function line = cartesianLine(varargin)
29%CARTESIANLINE Create a straight line from cartesian equation coefficients.
30%
31%   L = cartesianLine(A, B, C);
32%   Create a line verifying the Cartesian equation:
33%   A*x + B*x + C = 0;
34%
35%   See also:
36%   lines2d, createLine
37%
38%   ---------
39% Author: David Legland
40% e-mail: david.legland@grignon.inra.fr
41% created the 25/05/2004.
42% Copyright 2010 INRA - Cepia Software Platform.
43
44
45if length(varargin)==1
46    var = varargin{1};
47    a = var(:,1);
48    b = var(:,2);
49    c = var(:,3);
50elseif length(varargin)==3
51    a = varargin{1};
52    b = varargin{2};
53    c = varargin{3};
54end
55
56% normalisation factor
57d = a.*a + b.*b;
58
59x0 = -a.*c./d;
60y0 = -b.*c./d;
61theta = atan2(-a, b);
62dx = cos(theta);
63dy = sin(theta);
64
65line = [x0 y0 dx dy];
66