X-Git-Url: https://git.sesse.net/?p=movit;a=blobdiff_plain;f=dither_effect.h;h=314390752cebde884f87f8d54db798f33f310cae;hp=943220aed55ad3dc524e4404b06ef2838f917831;hb=f7e302b40026b15d1606269324a31953a1eadb80;hpb=f1a81dca72da9aa5103527b8c9494381204e70c5

diff --git a/dither_effect.h b/dither_effect.h
index 943220a..3143907 100644
--- a/dither_effect.h
+++ b/dither_effect.h
@@ -43,15 +43,28 @@
 // like many LCD monitors do, but it starts to get very hairy, again, for limited gains.)
 // The dither is also deterministic across runs.
 
+#include <GL/glew.h>
+#include <string>
+
 #include "effect.h"
 
 class DitherEffect : public Effect {
-public:
+private:
+	// Should not be instantiated by end users;
+	// call EffectChain::set_dither_bits() instead.
 	DitherEffect();
+	friend class EffectChain;
+
+public:
 	~DitherEffect();
 	virtual std::string effect_type_id() const { return "DitherEffect"; }
 	std::string output_fragment_shader();
 
+	// Note that if we did error diffusion, we'd actually want to diffuse the
+	// premultiplied error. However, we need to do dithering in the same
+	// space as quantization, whether that be pre- or postmultiply.
+	virtual AlphaHandling alpha_handling() const { return DONT_CARE_ALPHA_TYPE; }
+
 	void set_gl_state(GLuint glsl_program_num, const std::string &prefix, unsigned *sampler_num);
 
 private: