From b0181fa78c745774181ac371c9d5894e77c95c90 Mon Sep 17 00:00:00 2001
From: FrancescoC-Unity <francescoc@unity3d.com>
Date: Tue, 2 Feb 2021 17:35:55 +0100
Subject: [PATCH 1/2] Have two frames with reprojection off on cut (due to
 exposure)

---
 .../Runtime/RenderPipeline/Camera/HDCamera.cs                 | 3 +++
 .../Runtime/RenderPipeline/HDRenderPipeline.LightLoop.cs      | 4 +++-
 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/com.unity.render-pipelines.high-definition/Runtime/RenderPipeline/Camera/HDCamera.cs b/com.unity.render-pipelines.high-definition/Runtime/RenderPipeline/Camera/HDCamera.cs
index f8ab5ebeb03..4f39b97a5d8 100644
--- a/com.unity.render-pipelines.high-definition/Runtime/RenderPipeline/Camera/HDCamera.cs
+++ b/com.unity.render-pipelines.high-definition/Runtime/RenderPipeline/Camera/HDCamera.cs
@@ -83,6 +83,8 @@ public struct ViewConstants
         /// <summary>Volumetric history buffer state.</summary>
         public bool                 volumetricHistoryIsValid = false;
 
+        internal int                volumetricValidFrames = 0;
+
         /// <summary>Width actually used for rendering after dynamic resolution and XR is applied.</summary>
         public int                  actualWidth { get; private set; }
         /// <summary>Height actually used for rendering after dynamic resolution and XR is applied.</summary>
@@ -129,6 +131,7 @@ public void Reset()
             cameraFrameCount = 0;
             resetPostProcessingHistory = true;
             volumetricHistoryIsValid = false;
+            volumetricValidFrames = 0;
             colorPyramidHistoryIsValid = false;
         }
 
diff --git a/com.unity.render-pipelines.high-definition/Runtime/RenderPipeline/HDRenderPipeline.LightLoop.cs b/com.unity.render-pipelines.high-definition/Runtime/RenderPipeline/HDRenderPipeline.LightLoop.cs
index 6430d0dc524..e11be2585eb 100644
--- a/com.unity.render-pipelines.high-definition/Runtime/RenderPipeline/HDRenderPipeline.LightLoop.cs
+++ b/com.unity.render-pipelines.high-definition/Runtime/RenderPipeline/HDRenderPipeline.LightLoop.cs
@@ -742,8 +742,10 @@ TextureHandle VolumetricLightingPass(RenderGraph renderGraph, HDCamera hdCamera,
                                 FilterVolumetricLighting(data.parameters, data.lightingBuffer, ctx.cmd);
                         });
 
-                    if (parameters.enableReprojection)
+                    if (parameters.enableReprojection && hdCamera.volumetricValidFrames > 1)
                         hdCamera.volumetricHistoryIsValid = true; // For the next frame..
+                    else
+                        hdCamera.volumetricValidFrames++;
 
                     return passData.lightingBuffer;
                 }

From e13ee78629c8d1ac4a63f0958d7529ff60586a13 Mon Sep 17 00:00:00 2001
From: FrancescoC-Unity <francescoc@unity3d.com>
Date: Tue, 2 Feb 2021 17:46:42 +0100
Subject: [PATCH 2/2] changelog

---
 com.unity.render-pipelines.high-definition/CHANGELOG.md | 1 +
 1 file changed, 1 insertion(+)

diff --git a/com.unity.render-pipelines.high-definition/CHANGELOG.md b/com.unity.render-pipelines.high-definition/CHANGELOG.md
index 35db6b9a781..23f9cca4b46 100644
--- a/com.unity.render-pipelines.high-definition/CHANGELOG.md
+++ b/com.unity.render-pipelines.high-definition/CHANGELOG.md
@@ -14,6 +14,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 ### Fixed
 - Fixed an exception when opening the color picker in the material UI (case 1307143).
 - Fixed lights shadow frustum near and far planes.
+- White flashes on camera cuts on volumetric fog.
 
 ### Changed
 - Removed the material pass probe volumes evaluation mode.