13 Jun 2005
27 Oct 2014)
Geometry library for matlab. Performs geometric computations on points, lines, circles, polygons...
function res = orthogonalLine(line, point)
%ORTHOGONALLINE Create a line orthogonal to another one through a point
% PERP = orthogonalLine(LINE, POINT);
% Returns the line orthogonal to the line LINE and going through the
% point given by POINT. Directed angle from LINE to PERP is pi/2.
% LINE is given as [x0 y0 dx dy] and POINT is [xp yp].
% Works also when LINE is a N-by-4 array, or POINT is a N-by-2 array. In
% this case, the result is a N-by-4 array.
% refLine = createLine([10 10], [30 20]);
% pt = [20 40];
% figure; hold on; axis equal; axis([0 50 0 50]);
% drawLine(refLine, 'lineWidth', 2);
% perp = orthogonalLine(refLine, pt);
% drawLine(perp, 'color', 'r');
% See also:
% lines2d, parallelLine, intersectLines
% author : David Legland
% INRA - TPV URPOI - BIA IMASTE
% created the 31/10/2003.
% 19/02/2004 added control for multiple lines and/or points
% 31/12/2013 added example
N = max(size(point, 1), size(line, 1));
if size(point, 1)>1
res = point;
res = ones(N, 1)*point;
if size(line, 1)>1
res(:,3) = -line(:,4);
res(:,4) = line(:,3);
res(:,3) = -ones(N,1)*line(4);
res(:,4) = ones(N,1)*line(3);