anchor.diff:                             :shaders (list (make-instance 'lpsg:shader
                                                            :shader-type :vertex-shader
                                                            :source *vertex-shader-source*
  -                                                         :usets '(projection model))
  +                                                         :usets '(camera model))
                                             (make-instance 'lpsg:shader
                                                            :shader-type :fragment-shader
                                                            :source *fragment-shader-source*
  
positive.code: vec4 lightDir = vec4(-0.577350, -0.577350, -0.577350, 0);
  
  uniform mat4 projectionMatrix;
  uniform mat4 modelMatrix;
  
  void main()
  {
    // add a temporary model and view transform
    vec4 modelPos = modelMatrix * in_Position - vec4(0.25, 0.75, 0.0, 0.0);
    gl_Position = projectionMatrix * modelPos;
    float intense = max(dot(-in_Normal, lightDir.xyz), 0.0);
    theColor = intense * in_Color;
  
negative.code:               (if (eq (projection-type window) 'orthographic)
                    'perspective
                    'orthographic))
          (setf (projection-matrix *camera-uset*)
                (compute-projection-matrix window (projection-type window) 1.0 10.0))
          (draw-window window))
        (call-next-method)))
  