13 Jun 2005
27 Oct 2014)
Geometry library for matlab. Performs geometric computations on points, lines, circles, polygons...
function res = parallelLine(line, point)
%PARALLELLINE Create a line parallel to another one.
% RES = parallelLine(LINE, POINT);
% Returns the line with same direction vector than LINE and going through
% the point given by POINT.
% LINE is given as [x0 y0 dx dy] and POINT is [xp yp].
% RES = parallelLine(LINE, DIST);
% Uses relative distance to specify position. The new line will be
% located at distance DIST, counted positive in the right side of LINE
% and negative in the left side.
% P1 = [20 30]; P2 = [50 10];
% L1 = createLine([50 10], [20 30]);
% figure; hold on; axis equal; axis([0 60 0 50]);
% drawPoint([P1; P2], 'ko');
% drawLine(L1, 'k');
% P = [30 40];
% drawPoint(P, 'ko');
% L2 = parallelLine(L1, P);
% drawLine(L2, 'Color', 'b');
% See also:
% lines2d, orthogonalLine, distancePointLine, parallelEdge
% author : David Legland
% INRA - TPV URPOI - BIA IMASTE
% created the 31/10/2003.
% 31/07/2005 add usage of distance
% 15/06/2009 change convention for distance sign
% 31/09/2012 adapt for multiple lines
if size(point, 2) == 1
% use a distance. Compute position of point located at distance DIST on
% the line orthogonal to the first one.
point = pointOnLine([line(:,1) line(:,2) line(:,4) -line(:,3)], point);
% normal case: compute line through a point with given direction
res = zeros(size(line, 1), 4);
res(:, 1:2) = point;
res(:, 3:4) = line(:, 3:4);