CREATERAY Create a ray (half-line), from various inputs.

   RAY = createRay(POINT, ANGLE)
   POINT is a N*2 array giving starting point of the ray, and ANGLE is the
   orientation of the ray.

   RAY = createRay(X0, Y0, ANGLE)
   Specify ray origin with 2 input arguments.

   RAY = createRay(P1, P2)
   Create a ray starting from point P1 and going in the direction of point
   P2.

   Ray is represented in a parametric form: [x0 y0 dx dy]
   x = x0 + t*dx
   y = y0 + t*dy;
   for all t>0

   Example
   origin  = [3 4];
   theta   = pi/6;
   ray = createRay(origin, theta);
   figure(1); clf; hold on;
   axis([0 10 0 10]);
   drawRay(ray);

   See also:
   rays2d, createLine, points2d

 ------
 Author: David Legland
 e-mail: david.legland@grignon.inra.fr
 Created: 2007-10-18
 Copyright 2007 INRA - BIA PV Nantes - MIAJ Jouy-en-Josas.

Package: matgeom