From 9cc01e74a45655e0f281688dd4a7c908145fde0e Mon Sep 17 00:00:00 2001
From: Mugen87 <michael.herzog@human-interactive.org>
Date: Mon, 4 Sep 2017 18:09:14 +0200
Subject: [PATCH] common.glsl: Introduce linearToRelativeLuminance()

---
 examples/js/shaders/LuminosityShader.js       | 8 ++++----
 src/renderers/shaders/ShaderChunk/common.glsl | 9 +++++++++
 2 files changed, 13 insertions(+), 4 deletions(-)

diff --git a/examples/js/shaders/LuminosityShader.js b/examples/js/shaders/LuminosityShader.js
index b4244bc025..19dbbfca0f 100644
--- a/examples/js/shaders/LuminosityShader.js
+++ b/examples/js/shaders/LuminosityShader.js
@@ -29,6 +29,8 @@ THREE.LuminosityShader = {
 
 	fragmentShader: [
 
+		"#include <common>",
+
 		"uniform sampler2D tDiffuse;",
 
 		"varying vec2 vUv;",
@@ -37,11 +39,9 @@ THREE.LuminosityShader = {
 
 			"vec4 texel = texture2D( tDiffuse, vUv );",
 
-			"vec3 luma = vec3( 0.299, 0.587, 0.114 );",
-
-			"float v = dot( texel.xyz, luma );",
+			"float l = linearToRelativeLuminance( texel.rgb );",
 
-			"gl_FragColor = vec4( v, v, v, texel.w );",
+			"gl_FragColor = vec4( l, l, l, texel.w );",
 
 		"}"
 
diff --git a/src/renderers/shaders/ShaderChunk/common.glsl b/src/renderers/shaders/ShaderChunk/common.glsl
index 20e7d3c9f1..ad1db1a0c7 100644
--- a/src/renderers/shaders/ShaderChunk/common.glsl
+++ b/src/renderers/shaders/ShaderChunk/common.glsl
@@ -83,3 +83,12 @@ mat3 transpose( const in mat3 v ) {
 	return tmp;
 
 }
+
+// https://en.wikipedia.org/wiki/Relative_luminance
+float linearToRelativeLuminance( const in vec3 color ) {
+
+	vec3 weights = vec3( 0.2126, 0.7152, 0.0722 );
+
+	return dot( weights, color.rgb );
+
+}
-- 
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