From bd615692615c53206f4bdd1afd66cc2e91b78ea1 Mon Sep 17 00:00:00 2001
From: Marek Kost <mk.skelet@gmail.com>
Date: Mon, 10 Apr 2023 15:57:09 +0200
Subject: [PATCH] Linearize colors in frag shader

https://github.com/ocornut/imgui/issues/4890
---
 backends/vulkan/glsl_shader.frag | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/backends/vulkan/glsl_shader.frag b/backends/vulkan/glsl_shader.frag
index ce7e6f72b25d..70e4e2e536cf 100644
--- a/backends/vulkan/glsl_shader.frag
+++ b/backends/vulkan/glsl_shader.frag
@@ -8,7 +8,16 @@ layout(location = 0) in struct {
     vec2 UV;
 } In;
 
+vec4 to_linear(vec4 sRGB)
+{
+    bvec3 cutoff = lessThan(sRGB.rgb, vec3(0.04045));
+    vec3  higher = pow((sRGB.rgb + vec3(0.055)) / vec3(1.055), vec3(2.4));
+    vec3  lower  = sRGB.rgb / vec3(12.92);
+
+    return vec4(mix(higher, lower, cutoff), sRGB.a);
+}
+
 void main()
 {
-    fColor = In.Color * texture(sTexture, In.UV.st);
+    fColor = to_linear(In.Color) * to_linear(texture(sTexture, In.UV.st));
 }