cartesianLine

CARTESIANLINE Create a straight line from cartesian equation coefficients.

   L = cartesianLine(A, B, C);
   Create a line verifying the Cartesian equation:
   A*x + B*x + C = 0;

   See also
   lines2d, createLine

0001 function line = cartesianLine(varargin)
0002 %CARTESIANLINE Create a straight line from cartesian equation coefficients.
0003 %
0004 %   L = cartesianLine(A, B, C);
0005 %   Create a line verifying the Cartesian equation:
0006 %   A*x + B*x + C = 0;
0007 %
0008 %   See also
0009 %   lines2d, createLine
0010 
0011 % ------
0012 % Author: David Legland
0013 % E-mail: david.legland@inrae.fr
0014 % Created: 2004-05-25
0015 % Copyright 2004-2024 INRA - Cepia Software Platform
0016 
0017 if isscalar(varargin)
0018     var = varargin{1};
0019     a = var(:,1);
0020     b = var(:,2);
0021     c = var(:,3);
0022 elseif length(varargin)==3
0023     a = varargin{1};
0024     b = varargin{2};
0025     c = varargin{3};
0026 end
0027 
0028 % normalisation factor
0029 d = a.*a + b.*b;
0030 
0031 x0 = -a.*c./d;
0032 y0 = -b.*c./d;
0033 theta = atan2(-a, b);
0034 dx = cos(theta);
0035 dy = sin(theta);
0036 
0037 line = [x0 y0 dx dy];