X-Git-Url: https://git.sesse.net/?p=movit;a=blobdiff_plain;f=lift_gamma_gain_effect.h;h=bd1ec16a6d8743e6dfa83cd9848e78b959636a7c;hp=131957009a37bd35ccc954035f05a85ac03e358f;hb=ac040289928cdf3554ce884575afab17565e6c67;hpb=f99ad333a7acbb6c8c995dbb036484ae8940c490

diff --git a/lift_gamma_gain_effect.h b/lift_gamma_gain_effect.h
index 1319570..bd1ec16 100644
--- a/lift_gamma_gain_effect.h
+++ b/lift_gamma_gain_effect.h
@@ -16,6 +16,12 @@
 // rest of the curve relatively little. Thus, we actually convert to gamma 2.2
 // before lift, and then back again afterwards. (Gain and gamma are,
 // up to constants, commutative with the de-gamma operation.)
+//
+// Also, gamma is a case where we would not want premultiplied alpha.
+// Thus, we have to divide away alpha first, and then re-multiply it back later.
+
+#include <GL/glew.h>
+#include <string>
 
 #include "effect.h"
 
@@ -23,6 +29,7 @@ class LiftGammaGainEffect : public Effect {
 public:
 	LiftGammaGainEffect();
 	virtual std::string effect_type_id() const { return "LiftGammaGainEffect"; }
+	virtual AlphaHandling alpha_handling() const { return INPUT_PREMULTIPLIED_ALPHA_KEEP_BLANK; }
 	std::string output_fragment_shader();
 
 	void set_gl_state(GLuint glsl_program_num, const std::string &prefix, unsigned *sampler_num);