From d48042a258d1e9ba79f9eb3a71e54ed6d731c6f2 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Thomas=20L=C3=BCbking?= <thomas.luebking@gmail.com>
Date: Sun, 18 Dec 2011 19:41:14 +0100
Subject: [PATCH] use correct luminance calculation for greyscale

---
 scene-fragment.glsl | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/scene-fragment.glsl b/scene-fragment.glsl
index 22463c16c2..4b5424be16 100644
--- a/scene-fragment.glsl
+++ b/scene-fragment.glsl
@@ -12,10 +12,8 @@ void main() {
 
     tex.a += float(u_forceAlpha);
 
-    if( saturation != 1.0 ) {
-        vec3 desaturated = tex.rgb * vec3( 0.30, 0.59, 0.11 );
-        desaturated = vec3( dot( desaturated, tex.rgb ));
-        tex.rgb = tex.rgb * vec3( saturation ) + desaturated * vec3( 1.0 - saturation );
+    if (saturation != 1.0) {
+        tex.rgb = mix(vec3(dot( vec3( 0.30, 0.59, 0.11 ), tex.rgb )), tex.rgb, saturation);
     }
 
     tex *= modulation;