X-Git-Url: https://git.sesse.net/?a=blobdiff_plain;f=overlay_effect.h;fp=overlay_effect.h;h=06ff7939128257e9ccc006e3076b3e91b29aaeb5;hb=5e05605a85a15944b95d7000745446756cdcbfa8;hp=0000000000000000000000000000000000000000;hpb=49ef2523611e215b327cd26f7bf698d1516edd46;p=movit

diff --git a/overlay_effect.h b/overlay_effect.h
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+++ b/overlay_effect.h
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+#ifndef _OVERLAY_EFFECT_H
+#define _OVERLAY_EFFECT_H 1
+
+// Put one image on top of another, using alpha where appropriate.
+// (If both images are the same aspect and the top image has alpha=1.0
+// for all pixels, you will not see anything of the one on the bottom.)
+//
+// This is the “atop” operation from Porter-Duff blending, also used
+// when merging layers in e.g. GIMP or Photoshop.
+//
+// The first input is the bottom, and the second is the top.
+
+#include "effect.h"
+
+class OverlayEffect : public Effect {
+public:
+	OverlayEffect();
+	virtual std::string effect_type_id() const { return "OverlayEffect"; }
+	std::string output_fragment_shader();
+
+	virtual bool needs_srgb_primaries() const { return false; }
+	virtual unsigned num_inputs() const { return 2; }
+};
+
+#endif // !defined(_OVERLAY_EFFECT_H)