anchor.diff:    (glu-tess-end-contour (glu-tessellator tess)))
   
   (defmethod tess-end-polygon ((tess tessellator))
  -  (glu-tess-end-polygon (glu-tessellator tess))
  -  (free-tess-data tess))
  +  (glu-tess-end-polygon (glu-tessellator tess)))
  +;;  (free-tess-data tess))
   
   (defmethod tess-property ((tess tessellator) which value)
     (glu-tess-property (glu-tessellator tess) which value))
  
positive.code:           (register-callbacks obj)))))
  
  (defmethod tess-delete ((tess tessellator))
    (glu-delete-tess (glu-tessellator tess))
    (remhash (id tess) *tessellators*)
    (free-tess-data tess))
  
  (defmethod tess-begin-polygon ((tess tessellator) &optional (polygon-data nil))
    (let* ((polygon-data-id 
  
negative.code: 
  (defun get-tessellator (polygon-data-pointer)
    (unless (null-pointer-p polygon-data-pointer)
      (let ((tessellator-id (mem-aref polygon-data-pointer :uint64 0)))
        (or 
         (gethash tessellator-id *tessellators*)
         (error "Unable to get tessellator with id ~a" tessellator-id)))))
  
  (defun get-polygon-data (tess polygon-data-pointer)
    (unless (null-pointer-p polygon-data-pointer)
      (let ((polygon-data-id (mem-aref polygon-data-pointer :uint64 1)))
        (if (> polygon-data-id +nil-polygon-data-id+)
            (gethash polygon-data-id (polygon-data tess))
          nil))))
  
  