anchor.diff:  ")
   
   (lpsg:define-uset projection (("projectionMatrix" :float-mat4
  -                               projection-matrix :accessor projection-matrix)))
  +                                                  projection-matrix :accessor projection-matrix)))
  +
  +(lpsg:define-uset model (("modelMatrix" :float-mat4
  +                                        model-matrix :accessor model-matrix)))
   
   (defclass cube-window (viewer-window lpsg:renderer)
     ((cube :accessor cube)
  
positive.code: vec4 lightDir = vec4(-0.577350, -0.577350, -0.577350, 0);
  
  uniform mat4 projectionMatrix;
  
  void main()
  {
    // add a temporary model and view transform
    vec3 modelPos = in_Position + vec3(0.0, 0.0, -5.0) - vec3(0.25, 0.75, 0.0);
    gl_Position = projectionMatrix * vec4(modelPos, 1.0);
    float intense = max(dot(-in_Normal, lightDir.xyz), 0.0);
    theColor = intense * in_Color;
  }
  
negative.code:   (:default-initargs :exposed nil :projection-type 'orthographic))
  
  (defvar *proj-uset* (make-instance 'projection))
  (defvar *model-uset* (make-instance 'model))
  
  (defun draw-window (win)
    (when (exposed win)
  