anchor.diff:       src
        p-format
        1
  -     (gpu-array-bb-offset-in-bytes-into-buffer gpu-array-bb))
  +     (cffi:make-pointer
  +      (gpu-array-bb-offset-in-bytes-into-buffer gpu-array-bb))
  +     (gpu-array-bb-byte-size gpu-array-bb))
       gpu-array-bb))
   
   (defn copy-texture-backed-gpu-array-to-buffer-backed-gpu-array
  
positive.code:   (let ((pixel-format (lisp-type->pixel-format dst)))
      (setf (gpu-buffer-bound (cepl-context) :pixel-pack-buffer)
            (gpu-array-bb-buffer dst))
      (pack-pixels-from-texture src
                                pixel-format
                                (gpu-array-bb-row-alignment dst)
                                (gpu-array-bb-offset-in-bytes-into-buffer dst)))
    dst)
  
  (defn copy-texture-backed-gpu-array-to-new-lisp-data ((src gpu-array-t))
  
negative.code:   (let ((pixel-format (lisp-type->pixel-format
                         (c-array-element-type dst))))
      (setf (gpu-buffer-bound (cepl-context) :pixel-pack-buffer) nil)
      (pack-pixels-from-texture
       src
       pixel-format
       (c-array-row-alignment dst)
       (c-array-pointer dst)
       (cepl.c-arrays::%gl-calc-byte-size
        (c-array-element-byte-size dst)
        (gpu-array-dimensions src)
        (c-array-row-alignment dst))))
    dst)
  
  (defn copy-texture-backed-gpu-array-to-new-buffer-backed-gpu-array
  