anchor.diff:                (if (eq (projection-type window) 'orthographic)
                     'perspective
                     'orthographic))
  -        (setf (projection-matrix *proj-uset*)
  +        (setf (projection-matrix *camera-uset*)
                 (compute-projection-matrix window (projection-type window) 1.0 10.0))
           (draw-window window))
         (call-next-method)))
  
positive.code:   (draw-window window))
  
  (defmethod glop:on-event :after ((window cube-window) (event glop:resize-event))
    (setf (projection-matrix *proj-uset*)
          (compute-projection-matrix window (projection-type window) 1.0 10.0))
    (draw-window window))
  
  
negative.code:    (projection-type :accessor projection-type :initarg :projection-type))
    (:default-initargs :exposed nil :projection-type 'orthographic))
  
  (defvar *camera-uset* (make-instance 'camera))
  (defvar *model-uset* (make-instance 'model))
  
  (defun draw-window (win)
  