anchor.diff:  
   (defun assert-valid-args-for-buffer-backend-texture
       (image-format cubes rectangle multisample mipmap layer-count
  -     lod-bias min-lod max-lod minify-filter magnify-filter wrap compare
        texture-type)
     (when (or mipmap (not (= layer-count 1)) cubes rectangle multisample)
       (error 'buffer-backed-texture-invalid-args))
  -  (when (or lod-bias min-lod max-lod minify-filter magnify-filter wrap compare)
  -    (error 'buffer-backed-texture-invalid-samplers))
     (unless (valid-image-format-for-buffer-backed-texturep image-format)
       (error 'buffer-backed-texture-invalid-image-format
              :type-name image-format))
  
positive.code:                          initial-contents)))
           (result (%make-texture tex-obj dim mipmap layer-count cubes
  				buffer-storage rectangle multisample immutable
  				nil image-format lod-bias min-lod max-lod
                                  minify-filter magnify-filter wrap compare
                                  generate-mipmaps)))
      (loop :for data :in initial-contents :for i :from 0 :do
         (push-g data (texref result :cube-face i)))
      result))
  
  (defun %make-texture (tex-obj dimensions mipmap layer-count cubes buffer-storage
                        rectangle multisample immutable initial-contents
                        image-format lod-bias min-lod max-lod minify-filter
                        magnify-filter wrap compare generate-mipmaps)
    (let* ((dimensions (listify dimensions))
  	 (dimensions (%texture-dimensions initial-contents dimensions)))
      ;; check for power of two - handle or warn
  
negative.code:                      &key dimensions element-type (mipmap nil)
                         (layer-count 1) (cubes nil) (rectangle nil)
                         (multisample nil) (immutable t) (buffer-storage nil)
                         (generate-mipmaps t))
    (cepl.memory::if-context
     (make-texture-now %pre% initial-contents dimensions element-type mipmap
  		     layer-count cubes rectangle multisample immutable
  		     buffer-storage generate-mipmaps)
     (make-uninitialized-texture)
     (when (typep initial-contents 'gpu-array-bb)
       (list initial-contents))))
  
  (defun make-texture-now (tex-obj initial-contents dimensions element-type mipmap
  			 layer-count cubes rectangle multisample immutable
  			 buffer-storage generate-mipmaps)
    ;;
    (let ((element-type (expand-gl-type-name element-type))
  	(image-format (calc-image-format element-type initial-contents)))
  