anchor.diff:  
   (in-package #:cl-glut-examples)
   
  -;;;GLuint startList;
   (defparameter *start-list* nil)
   
   (defclass tess-window (glut:window)
  
positive.code:                      :mode '(:single :rgb)))
  
  (defclass example-tessellator (glu:tessellator)
    ())
  
  (defmethod glut:display ((w tess-window))
  
negative.code:     (glu:tess-end-contour tobj)
      (glu:tess-end-polygon tobj)
      (gl:end-list)
      
    ;;;; smooth shaded, self-intersecting star
      (setf tobj (make-instance 'star-tessellator))
      (gl:new-list (1+ *start-list*) :compile)
      (gl:shade-model :smooth)
      (glu:tess-property tobj :tess-winding-rule glu:+tess-winding-positive+)
      (glu:tess-begin-polygon tobj nil)
      (glu:tess-begin-contour tobj)
      (loop for coords in star
         do (glu:tess-vertex tobj coords))                           
      (glu:tess-end-contour tobj)
      (glu:tess-end-polygon tobj)
      (gl:end-list)))
  
  (defun rb-tess ()
    (setf glut:*run-main-loop-after-display* nil)
  