anchor.diff:      (loop
          for model-input in (list *model-input* *model-input2*)
          for i from 0
  -       for cube = (make-cube model-input allocator (effect window))
  +       for cube = (make-cube model-input allocator window)
          for cube-visible = (make-instance 'lpsg:input-value-node :value t)
          do (progn
               (setf (lpsg:input cube 'lpsg:visiblep) cube-visible)
  
positive.code:   (draw-window window))
  
  (defmethod glop:on-event :after ((window cube-window) (event glop:resize-event))
    (setf (projection-matrix *camera-uset*)
          (compute-projection-matrix window (projection-type window) 1.0 10.0))
    (setf (lpsg:value *camera-input*) *camera-uset*)
    (draw-window window))
  
  (defmethod glop:on-event ((window cube-window) (event glop:key-event))
  
negative.code:                                   :attribute-map '((gl:vertex . "in_Position")
                                                     (gl:normal . "in_Normal"))
                                    :uset-names '(camera model light))))
        (setf (model-matrix *model-uset*) (sb-cga:translate* 1.0 0.0 -5.0))
        (setf (model-matrix *model-uset2*) (sb-cga:translate* -1.0 0.0 -5.0))
        (setf (light-direction *light-uset*) (compute-light-vector))
  