anchor.diff:  	    
   	    (:keydown
   	     (:keysym keysym)
  -     	     (when (sdl2:scancode= (sdl2:scancode-value keysym) :scancode-t)
  -
  -	       )
  -
  +     	     (when (sdl2:scancode= (sdl2:scancode-value keysym) :scancode-i)
  +	       (incf *light-height*))
  +	     (when (sdl2:scancode= (sdl2:scancode-value keysym) :scancode-k)
  +	       (decf *light-height*))
  +	     (when (sdl2:scancode= (sdl2:scancode-value keysym) :scancode-l)
  +	       (incf *light-radius*))
  +	     (when (sdl2:scancode= (sdl2:scancode-value keysym) :scancode-j)
  +	       (decf *light-radius*))
  +	     
   	     (when (sdl2:scancode= (sdl2:scancode-value keysym) :scancode-y)
   	       ;; toggle light rendering
   	       (setf *draw-light* (not *draw-light*)))
  
positive.code: 
  (defun calc-light-position ()
    ;;NEXT-TODO:
    (glm:vec3 0.0 *light-height* 0.0))
  
  (defun draw ()
    (let* ((model-matrix (make-instance 'glutil:matrix-stack))
  
negative.code: 	 (light-pos-camera-space
  	  ;; TODO: make mat*vec smarter so we don't need to cast so much in code?
  	  (glm:vec4->vec3 (glm:mat*vec (glutil:top-ms model-matrix)
  				       world-light-pos))))
  
      (glutil:set-matrix model-matrix (glutil:calc-matrix *view-pole*))
  
  