From c63fd2e72b4cd4a41dec00c36597d4be6e122b4f Mon Sep 17 00:00:00 2001
From: Leon Styhre <leon@leonstyhre.com>
Date: Thu, 15 Dec 2022 19:13:37 +0100
Subject: [PATCH] Fixed a premultiplied alpha shader issue that lead to
 artifacting when brightness was adjusted.

---
 resources/shaders/glsl/core.glsl      | 1 +
 resources/shaders/glsl/scanlines.glsl | 1 +
 2 files changed, 2 insertions(+)

diff --git a/resources/shaders/glsl/core.glsl b/resources/shaders/glsl/core.glsl
index b17415b03..9e60a02d2 100644
--- a/resources/shaders/glsl/core.glsl
+++ b/resources/shaders/glsl/core.glsl
@@ -73,6 +73,7 @@ void main()
 
     // Brightness.
     if (brightness != 0.0) {
+        sampledColor.rgb /= sampledColor.a;
         sampledColor.rgb += 0.3 * brightness;
         sampledColor.rgb *= sampledColor.a;
     }
diff --git a/resources/shaders/glsl/scanlines.glsl b/resources/shaders/glsl/scanlines.glsl
index 923e70290..39df227f4 100644
--- a/resources/shaders/glsl/scanlines.glsl
+++ b/resources/shaders/glsl/scanlines.glsl
@@ -158,6 +158,7 @@ void main()
 
     // Brightness.
     if (brightness != 0.0) {
+        colorTemp.rgb /= colorTemp.a;
         colorTemp.rgb += 0.3 * brightness;
         colorTemp.rgb *= colorTemp.a;
     }