From 3fae7bb2cee76430a99cd1077619e73a5209e89d Mon Sep 17 00:00:00 2001
From: Reach Platform Support <svc-reach-platform-support@unity3d.com>
Date: Fri, 9 Aug 2024 11:16:33 +0000
Subject: [PATCH] [Port] [2022.3] [Vulkan][URP] Fix linear fog rendering
 artifacts on Adreno GPUs with Vulkan

Jira: https://jira.unity3d.com/browse/UUM-61728
Read the Comments to Reviewers section.
---
 .../ShaderLibrary/ShaderVariablesFunctions.hlsl                | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/Packages/com.unity.render-pipelines.universal/ShaderLibrary/ShaderVariablesFunctions.hlsl b/Packages/com.unity.render-pipelines.universal/ShaderLibrary/ShaderVariablesFunctions.hlsl
index be0c362ebf3..7bd0c8d9895 100644
--- a/Packages/com.unity.render-pipelines.universal/ShaderLibrary/ShaderVariablesFunctions.hlsl
+++ b/Packages/com.unity.render-pipelines.universal/ShaderLibrary/ShaderVariablesFunctions.hlsl
@@ -393,7 +393,8 @@ half3 MixFogColor(half3 fragColor, half3 fogColor, half fogFactor)
 {
     #if defined(FOG_LINEAR) || defined(FOG_EXP) || defined(FOG_EXP2)
         half fogIntensity = ComputeFogIntensity(fogFactor);
-        fragColor = lerp(fogColor, fragColor, fogIntensity);
+        // Workaround for UUM-61728: using a manual lerp to avoid rendering artifacts on some GPUs when Vulkan is used
+        fragColor = fragColor * fogIntensity + fogColor * (half(1.0) - fogIntensity);
     #endif
     return fragColor;
 }