anchor.diff:       for bundle in (bundles renderer)
        for geom = (geometry bundle)
        do (progn
  +          (bind-state renderer (gl-state bundle))
             (gl:bind-vertex-array (vao geom))
             (if (indices geom)
                 (let ((index-offset (allocation-offset
  
positive.code:                      :initform nil)
     (log :reader render-error-log :initarg :error-log :initform nil))
    (:report report-render-error))
  
  ;;; A simple reference counting protocol for objects that should do some
  ;;; cleanup e.g., release OpenGL resources, when they are no longer used.
  
negative.code: 
  (defgeneric draw (renderer))
  
  (defgeneric bind-state (renderer state))
  
  (defmethod bind-state ((renderer renderer) (state graphics-state))
    )
  
  (defun draw-render-groups (renderer)
    (upload-bundles renderer)
    (draw renderer))
  