anchor.diff:  (defparameter *pov-indent-width* 3) ;; as used in povray.org docs
   
   ;; Convert something to a POV-ray object
  -(defgeneric pov-object (object))
   
   (defmacro with-pov-indent (old-indent &body body)
     `(let* ((,old-indent *pov-indent*)
  
positive.code:                      (vec-y elements)
                       (vec-z elements)))
  
  
  (defmethod pov-object ((object vec3))
    (with-vec3 (x y z) object
      (%pov-float-vector x z y)))
  
  (defun pov-float-vector-right (elements)
    (pov-object (vec3* (vec-x elements)
                       (vec-y elements)
                       (vec-z elements))))
  
  
  (defun pov-integer-vector (elements)
    (apply #'%pov-integer-vector elements))
  
  (defmethod print-object ((object pov-float-vector) stream)
    (format stream "~&~A<~F, ~F, ~F>"
  
negative.code:   (loop for x in (pov-sequence-statements object)
       do (print-object x stream)))
  
  