anchor.diff:  
   (defclass std-140 (gl-layout) ())
   (defclass std-430 (gl-layout) ())
  +
  +(defmethod print-object ((obj std-140) stream)
  +  (print-unreadable-object ((v! 1 2 3) stream :identity t)
  +    (format stream "STD-140 ~a" (type->type-spec (layout-varjo-type obj)))))
   
   (defun calc-block-layout (varjo-struct-type-name)
     (let ((type (type-spec->type varjo-struct-type-name))
  
positive.code:     (make-instance
       'std-140
       :name name
       :base-offset base-offset
       :base-alignment base-alignment
       :aligned-offset (calc-aligned-offset base-offset base-alignment)
  
negative.code:        (make-instance
          'std-140
          :name name
          :type type
          :base-offset base-offset
          :aligned-offset (calc-aligned-offset base-offset base-alignment)
          :base-alignment base-alignment
  