lib/walker.js
function calcDirection(start, end) {
  var direction = new Vec2(end);
  direction.subtract(start);
  direction.normalize();
  return direction;
}
function calcDirection(start, end) {
  var direction = new Vec2(end);
  direction.subtract(start);
  direction.normalize();
  return direction;
}
function calcDirection ( start , end ) { var direction = new Vec2 ( end ) ; direction . subtract ( start ) ; direction . normalize ( ) ; return direction ; }
Figure out direction vector of line connecting two points.

@param {Vec2} start
@param {Vec2} end
@return {Vec2} normalized direction vector
Figure out direction vector of line connecting two points .