// where we first blur the picture, and then overlay it on the original
// using the original as a matte.
+#include <GL/glew.h>
+#include <assert.h>
+#include <string>
+
#include "effect.h"
class BlurEffect;
+class EffectChain;
+class Node;
class OverlayMatteEffect;
class DiffusionEffect : public Effect {