anchor.diff:                          (if start-arrow start-arrow-length 0)
                           (if end-arrow end-arrow-length 0))))
   
  -    (nconc (when start-arrow
  +    (nconc (list (item-cylinder-axis parent name
  +                                     :options options
  +                                     :height body-length :radius (/ width 2)
  +                                     :axis axis
  +                                     :translation (if start-arrow
  +                                                      (g+ (g* start-arrow-length axis)
  +                                                          translation)
  +                                                      translation)))
  +           (when start-arrow
                (list (item-cone-axis parent (draw-subframe name "start-arrow")
                                      :options options
                                      :height start-arrow-length
  
positive.code:                                  offset
                                   angle
                                   end-arrow
                                   (end-arrow-start-width (* 2 width))
                                   (end-arrow-end-width 0d0)
                                   (end-arrow-length width)
                                   start-arrow
                                   (start-arrow-start-width (* 2 width))
                                   (start-arrow-end-width 0d0)
                                   (start-arrow-length width)
                                   )
    (declare (ignore scene-graph))
    (let* ((start-angle (if start-arrow
  
negative.code:                                :options options
                                 :height end-arrow-length
                                 :start-radius (/ end-arrow-start-width 2)
                                 :end-radius 0
                                 :axis (transform R (vec3* 0 1 0))
                                 :translation (transform R (vec3* radius 0 0))
                                 ))))
  