X-Git-Url: https://git.sesse.net/?p=movit;a=blobdiff_plain;f=gamma_expansion_effect.cpp;h=f51dc21c17dad084e98491227fffe35e3e4f474e;hp=9025b0b9ac767731d3bb60806fb9372e8b2ef6cc;hb=85f9719bf3519b1f1942738d11601584f5d38725;hpb=111c1867b9b6096a8e96650a74659806387b11c1

diff --git a/gamma_expansion_effect.cpp b/gamma_expansion_effect.cpp
index 9025b0b..f51dc21 100644
--- a/gamma_expansion_effect.cpp
+++ b/gamma_expansion_effect.cpp
@@ -5,13 +5,15 @@
 #include "gamma_expansion_effect.h"
 #include "util.h"
 
+using namespace std;
+
 GammaExpansionEffect::GammaExpansionEffect()
 	: source_curve(GAMMA_LINEAR)
 {
 	register_int("source_curve", (int *)&source_curve);
 }
 
-std::string GammaExpansionEffect::output_fragment_shader()
+string GammaExpansionEffect::output_fragment_shader()
 {
 	if (source_curve == GAMMA_LINEAR) {
 		return read_file("identity.frag");
@@ -24,7 +26,7 @@ std::string GammaExpansionEffect::output_fragment_shader()
 	assert(false);
 }
 
-void GammaExpansionEffect::set_gl_state(GLuint glsl_program_num, const std::string &prefix, unsigned *sampler_num)
+void GammaExpansionEffect::set_gl_state(GLuint glsl_program_num, const string &prefix, unsigned *sampler_num)
 {
 	Effect::set_gl_state(glsl_program_num, prefix, sampler_num);
 
@@ -72,8 +74,11 @@ void GammaExpansionEffect::set_gl_state(GLuint glsl_program_num, const std::stri
 		// From the Wikipedia article on sRGB; ɑ (called a+1 there) = 1.055,
 		// β = 0.04045, ɣ = 2.4.
 		// maxerror      = 0.000094
-		// error at beta = 0.000094
-		// error at 1.0  = 0.000094
+		// error at beta = 0.000012
+		// error at 1.0  = 0.000012
+		//
+		// Note that the worst _relative_ error by far is just at the beginning
+		// of the exponential curve, ie., just around β.
 		set_uniform_float(glsl_program_num, prefix, "linear_scale", 1.0 / 12.92);
 		set_uniform_float(glsl_program_num, prefix, "c0", 0.001324469581);
 		set_uniform_float(glsl_program_num, prefix, "c1", 0.02227416690);