Fix atmospheric scattering precision

com.unity.render-pipelines.high-definition/CHANGELOG.md

@@ -22,6 +22,7 @@ The version number for this package has increased due to a version update of a r
 - Fixed the possibility to have a shader with a pre-refraction render queue and refraction enabled at the same time.
 - Fixed a migration issue with the rendering queue in ShaderGraph when upgrading to 10.x;
 - Fixed upside down XR occlusion mesh.
+- Fixed precision issue with the atmospheric fog.
 
 ### Changed
 - Combined occlusion meshes into one to reduce draw calls and state changes with XR single-pass.

com.unity.render-pipelines.high-definition/Runtime/Lighting/AtmosphericScattering/OpaqueAtmosphericScattering.shader

@@ -67,7 +67,7 @@ Shader "Hidden/HDRP/OpaqueAtmosphericScattering"
             float3 volColor, volOpacity;
             AtmosphericScatteringCompute(input, V, depth, volColor, volOpacity);
 
-            return float4(volColor, volOpacity.x);
+            return float4(volColor, 1.0 - volOpacity.x);
         }
 
         float4 FragMSAA(Varyings input, uint sampleIndex: SV_SampleIndex) : SV_Target
@@ -80,7 +80,7 @@ Shader "Hidden/HDRP/OpaqueAtmosphericScattering"
             float3 volColor, volOpacity;
             AtmosphericScatteringCompute(input, V, depth, volColor, volOpacity);
 
-            return float4(volColor, volOpacity.x);
+            return float4(volColor, 1.0 - volOpacity.x);
         }
 
         float4 FragPBRFog(Varyings input) : SV_Target
@@ -118,7 +118,7 @@ Shader "Hidden/HDRP/OpaqueAtmosphericScattering"
         Pass
         {
             Cull Off    ZWrite Off
-            Blend One OneMinusSrcAlpha // Premultiplied alpha
+            Blend One SrcAlpha // Premultiplied alpha
             ZTest Less  // Required for XR occlusion mesh optimization
 
             HLSLPROGRAM
@@ -131,7 +131,7 @@ Shader "Hidden/HDRP/OpaqueAtmosphericScattering"
         Pass
         {
             Cull Off    ZWrite Off
-            Blend One OneMinusSrcAlpha // Premultiplied alpha
+            Blend One SrcAlpha // Premultiplied alpha
             ZTest Less  // Required for XR occlusion mesh optimization
 
             HLSLPROGRAM