anchor.diff:  
   
   ;; now acts a lot like a C++-struct, (:conc-name NIL) ensures that the automatically
  -;; reader functions of a struct don't start with program-data-.. which is the default
  -;; behaviour but with nothing at all, NIL. A string could be specified after :conc-name
  -;; to get custom prefix reader string: (:conc-name "foo-") -> (foo-the-program obj)
  -;; This solution has been chosen, instead of
  -;; (defclass program-data (...) :accessor the-program)
  -;; due to DEFCLASS considered overkill. Plus it has a nice print representation by
  -;; default.  hmmm TODO: (class-of <program-data-obj>) ==> #<STRUCTURE-CLASS TEST>
  +;; generated reader functions of a struct don't start with program-data-.. which is the
  +;; default behaviour but with nothing at all, NIL. A string could be specified after
  +;; :conc-name to get custom prefix reader string: (:conc-name "foo-") -> (foo-the-program
  +;; obj) This solution has been chosen, instead of (defclass program-data (...) :accessor
  +;; the-program) due to DEFCLASS considered overkill. Plus it has a nice print
  +;; representation by default.  hmmm TODO: (class-of <program-data-obj>) ==>
  +;; #<STRUCTURE-CLASS TEST>
   (defstruct (program-data (:conc-name NIL)) ; don't hyphenate struct readers
     the-program
   
  
positive.code: ;; TODO: sbcl specifics?
  (declaim (optimize (speed 0) (safety 3) (debug 3)))
  
  ;; TODO: about
  
  
  ;; REMEMBER: the lighting intensity is already given, and the light
  ;;           direction IS ALREADY IN CAMERA SPACE, the shader doesn't
  ;;           do anything regarding that
  ;;
  ;;           TWO vertex-shaders are used!
  (in-package #:arc-9)
  
  ;; TODO: this might solve the problem:
  ;; (print (uiop/lisp-build:current-lisp-file-pathname)) ?
  ;; TODO: they're identical in all following tutorials? Then remove *glsl-directory*
  (defvar *data-directory*
    (merge-pathnames
     #p "9-chapter/data/" (asdf/system:system-source-directory :arcsynthesis)))
  
negative.code:     (gl:bind-buffer :uniform-buffer 0))
    (%gl:viewport 0 0 w h))
  
  
  (defun mouse-rel-transform (xrel yrel)
    "Allow to look around with the mouse, just like in egoshooters."
  