anchor.diff:                                     :axis axis
                                      :translation  (g+ (g* axis start-arrow-length)
                                                                translation))))
  -           (list (item-cylinder-axis parent (draw-subframe name "body")
  -                                     :options options
  -                                     :height body-length :radius (/ width 2)
  -                                     :axis axis
  -                                     :translation (if start-arrow
  -                                                      (g+ (g* start-arrow-length axis)
  -                                                          translation)
  -                                                      translation)))
  +
              (when end-arrow
                (list (item-cone-axis parent (draw-subframe name "end-arrow")
                                      :options options
  
positive.code:                         (if start-arrow start-arrow-length 0)
                          (if end-arrow end-arrow-length 0))))
  
      (nconc (when start-arrow
               (list (item-cone-axis parent (draw-subframe name "start-arrow")
                                     :options options
                                     :height start-arrow-length
  
negative.code:                                  offset
                                   angle
                                   end-arrow
                                   (arrow-width (* 2 width))
                                   (arrow-length (* 2 width))
                                   (end-arrow-start-width arrow-width)
                                   (end-arrow-length arrow-length)
                                   start-arrow
                                   (start-arrow-start-width arrow-width)
                                   (start-arrow-length arrow-length)
                                   )
    (declare (ignore scene-graph))
    (let* ((start-angle (if start-arrow
  