anchor.diff:  
   
   (defun context-add-geometry (context parent name tf geometry &key
  +                                                               no-shadow
                                                                  (color '(0 0 0))
                                                                  (alpha 1d0)
                                                                  (collision t)
  
positive.code:       (context-add-cylinder context frame-name (subframe "x")
                              (quaternion-translation-2 nil (vec3* l/2 0 0))
                              length w/2 '(1 0 0)
                              :color '(1 0 0) :collision nil)
  
        (context-add-cylinder  context frame-name (subframe "y")
                               (quaternion-translation-2 nil (vec3* 0 l/2 0))
                               length w/2 '(0 1 0)
                               :color '(0 1 0) :collision nil)
        (context-add-cylinder  context frame-name (subframe "z")
                               (quaternion-translation-2 nil (vec3* 0 0 l/2))
                               length w/2 '(0 0 1)
                               :color '(0 0 1) :collision nil)
  
        (context-add-cone context frame-name (subframe "x_arrow")
                          (quaternion-translation-2 nil (vec3* length 0 0))
                          arrow-length cone-radius 0d0 '(1 0 0)
                          :color '(1 0 0) :collision nil)
  
        (context-add-cone context frame-name (subframe "y_arrow")
                          (quaternion-translation-2 nil (vec3* 0 length 0))
                          arrow-length cone-radius 0d0 '(0 1 0)
                          :color '(0 1 0) :collision nil)
  
        (context-add-cone context frame-name (subframe "z_arrow")
                          (quaternion-translation-2 nil (vec3* 0 0 length))
                          arrow-length cone-radius 0d0 '(0 0 1)
                          :color '(0 0 1) :collision nil)
        )
  
  
negative.code:                                   name
                                    (robray::make-scene-visual :geometry geometry
                                                               :color color
                                                               :alpha alpha
                                                               :modifiers (when no-shadow '(:no-shadow)))))))
  
  (defun context-add-sphere (context parent name tf radius &key
                                                             no-shadow
                                                             (color '(0 0 0))
                                                             (alpha 1d0)
                                                             (collision t)
                                                             (visual t))
    ;; Scene Graph
    (context-add-geometry context parent name tf (scene-sphere radius)
                          :no-shadow no-shadow
                          :color color :alpha alpha
                          :collision collision :visual visual)
    ;; Move It Scene
  