anchor.diff:  	(setf
   	 mirror (mirror)
   	 corners (corners mirror)
  -	 projection (projection mirror)
  +	 projection (projection corners)
   	 incident (incident)
   	 absorb-arrow (new (3fn *arrow-helper incident origin 10 0xffff00))
   	 visibility
  
positive.code: 	    (timefactor 10)
  	    (pause false)
  	    (time false))
  	(with-slots (sail scene mirror projection absorb-arrow controls render toggle-pause update animate init incidence space-pause-event update-tilt) app
  	  (setf
  	   toggle-pause
  	   (lambda (e)
  
negative.code: 	     (setf corners (corners mirror))
  	     ;; Projection
  	     ((@ scene remove) projection)
  	     (setf projection (projection corners))
  	     ((@ scene add) projection)
  	     ;; Update absorbed arrow
  	     ((@ absorb-arrow set-length) (* 10 (/ absorbed 100)))))
  