anchor.diff:  (defmethod make-default-glstate-member ((name (eql 'glstate-framebuffers)))
     (make-instance 'gl-framebuffers))
   
  -
   (define-gl-object framebuffer-object ()
     ((color-attachments :accessor color-attachments :initarg :color-attachments :initform nil
                         :documentation "plist of attachment names and attachment specs. An attachment
  
positive.code: (defmethod make-default-glstate-member ((name (eql 'glstate-front-face)))
    (make-instance 'gl-front-face))
  
  (defclass gl-framebuffers ()
    ((read-fbo :accessor read-fbo :initarg :read-fbo :initform nil)
     (draw-fbo :accessor draw-fbo :initarg :draw-fbo :initform nil)))
  
  (defmethod gl-finalize ((obj gl-framebuffers) &optional errorp)
    (let ((read-fbo (read-fbo obj))
  
negative.code:    (gl-draw-buffers :accessor gl-draw-buffers :initarg :gl-draw-buffers
                      :initform '(:color-attachment0))))
  
  (defgeneric attach-framebuffer-texture (fb-target attachment-point texture &key))
  
  (defmethod attach-framebuffer-texture (fb-target attachment-point (texture texture-2d)
                                         &key (level 0))
    (gl:framebuffer-texture-2d fb-target attachment-point (target texture) (id texture) level))
  
  (defmethod attach-framebuffer-texture (fb-target attachment-point (buffer renderbuffer) &key)
    (gl:framebuffer-renderbuffer fb-target attachment-point :renderbuffer (id buffer)))
  
  (defmethod gl-finalize ((obj framebuffer-object) &optional errorp)
    (flet ((get-attachment (tex)
  