anchor.diff:  
   (defn viewport-for-array ((arr (or null gpu-array))) (or null viewport)
     (when arr
  -    (make-viewport (gpu-array-dimensions arr) (vec2 0f0 0f0))))
  +    (let* ((dims (gpu-array-dimensions arr))
  +           (vdims (if (= (length dims) 1)
  +                      (list (first dims) 1)
  +                      dims)))
  +      (make-viewport vdims (vec2 0f0 0f0)))))
   
   ;;----------------------------------------------------------------------
   
  
positive.code:           (fixed-sample-locations nil))
        (or (first args) '(nil))
      (let ((dimensions (or (listify dimensions)
                            (viewport-dimensions (current-viewport)))))
        (assert (not (eq (first dimensions) 'quote)) ()
                'quote-symbol-found-in-fbo-dimensions
                :form (first args))
  
negative.code:              :dimensions dimensions
               :layer-count layer-count
               :samples samples
               :viewport (make-viewport viewport-dims)
               :fixed-sample-locations-p (not (null fixed-sample-locations))))
        ;; return nil as we have nothing that needs to be initialized
        ;; before the fbo can be initialized (no dependancies).
  