anchor.diff:  
   
   (defun wavefront-povray (obj-file output-file
  -                         &key (handedness :right))
  +                         &key
  +                           (handedness :right)
  +                           (directory *robray-tmp-directory*))
     (let* ((mesh-data (wavefront-obj-load obj-file))
            (name (mesh-data-name mesh-data)))
       (output (pov-declare (mesh-data-name mesh-data)
                            (pov-mesh2 :mesh-data mesh-data :handedness handedness))
  -            output-file)
  +            output-file :directory directory)
       name))
   
   
  
positive.code:     (let* ((file-type (string-downcase (file-type mesh-file)))
             (file-basename (file-basename mesh-file))
             (file-dirname (file-dirname mesh-file))
             (output-file (format-pathname "~A/povray/~A/~A.inc"
                                           directory file-dirname file-basename)))
      (string-case file-type
        ("obj" (handle-obj mesh-file output-file :right))
        ("stl"
  
negative.code:                       (directory *robray-tmp-directory*))
    ;; Maybe convert
    (labels ((handle-obj (obj-file output-file handedness)
               (let ((name (wavefront-povray obj-file output-file
                                             :handedness handedness
                                             :directory directory)))
                 (values name output-file)))
             (handle-dae (dae-file output-file)
               (convert dae-file output-file :right))
  