From 7a0c4e942375f6ca665232b46b8c9edc1a76045f Mon Sep 17 00:00:00 2001
From: hyzboy <hyzboy@gmail.com>
Date: Mon, 20 Jan 2020 17:42:45 +0800
Subject: [PATCH] add ToneMapping.glsl

---
 res/shader/ToneMapping.glsl | 85 +++++++++++++++++++++++++++++++++++++
 1 file changed, 85 insertions(+)
 create mode 100644 res/shader/ToneMapping.glsl

diff --git a/res/shader/ToneMapping.glsl b/res/shader/ToneMapping.glsl
new file mode 100644
index 00000000..a714b549
--- /dev/null
+++ b/res/shader/ToneMapping.glsl
@@ -0,0 +1,85 @@
+/*
+
+This shader experiments the effect of different tone mapping operators.
+This is still a work in progress.
+
+More info:
+http://slideshare.net/ozlael/hable-john-uncharted2-hdr-lighting
+http://filmicgames.com/archives/75
+http://filmicgames.com/archives/183
+http://filmicgames.com/archives/190
+http://imdoingitwrong.wordpress.com/2010/08/19/why-reinhard-desaturates-my-blacks-3/
+http://mynameismjp.wordpress.com/2010/04/30/a-closer-look-at-tone-mapping/
+http://renderwonk.com/publications/s2010-color-course/
+
+--
+Zavie
+
+*/
+
+vec3 linearToneMapping(vec3 color)
+{
+	float exposure = 1.;
+	color = clamp(exposure * color, 0., 1.);
+	color = pow(color, vec3(1. / gamma));
+	return color;
+}
+
+vec3 simpleReinhardToneMapping(vec3 color)
+{
+	float exposure = 1.5;
+	color *= exposure/(1. + color / exposure);
+	color = pow(color, vec3(1. / gamma));
+	return color;
+}
+
+vec3 lumaBasedReinhardToneMapping(vec3 color)
+{
+	float luma = dot(color, vec3(0.2126, 0.7152, 0.0722));
+	float toneMappedLuma = luma / (1. + luma);
+	color *= toneMappedLuma / luma;
+	color = pow(color, vec3(1. / gamma));
+	return color;
+}
+
+vec3 whitePreservingLumaBasedReinhardToneMapping(vec3 color)
+{
+	float white = 2.;
+	float luma = dot(color, vec3(0.2126, 0.7152, 0.0722));
+	float toneMappedLuma = luma * (1. + luma / (white*white)) / (1. + luma);
+	color *= toneMappedLuma / luma;
+	color = pow(color, vec3(1. / gamma));
+	return color;
+}
+
+vec3 RomBinDaHouseToneMapping(vec3 color)
+{
+    color = exp( -1.0 / ( 2.72*color + 0.15 ) );
+	color = pow(color, vec3(1. / gamma));
+	return color;
+}
+
+vec3 filmicToneMapping(vec3 color)
+{
+	color = max(vec3(0.), color - vec3(0.004));
+	color = (color * (6.2 * color + .5)) / (color * (6.2 * color + 1.7) + 0.06);
+	return color;
+}
+
+vec3 Uncharted2ToneMapping(vec3 color)
+{
+	float A = 0.15;
+	float B = 0.50;
+	float C = 0.10;
+	float D = 0.20;
+	float E = 0.02;
+	float F = 0.30;
+	float W = 11.2;
+	float exposure = 2.;
+	color *= exposure;
+	color = ((color * (A * color + C * B) + D * E) / (color * (A * color + B) + D * F)) - E / F;
+	float white = ((W * (A * W + C * B) + D * E) / (W * (A * W + B) + D * F)) - E / F;
+	color /= white;
+	color = pow(color, vec3(1. / gamma));
+	return color;
+}