Fix for white flash happening when changing lighting condition (like teleport)

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

@@ -535,6 +535,8 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 - Fix issue causing wrong planar reflection rendering when more than one camera is present.
 - Fix black screen in XR when HDRP package is present but not used.
 - Fixed an issue with the specularFGD term being used when the material has a clear coat (lit shader).
+- Fixed white flash happening with auto-exposure in some cases (case 1223774)
+- Fixed NaN which can appear with real time reflection and inf value
 
 ### Changed
 - Color buffer pyramid is not allocated anymore if neither refraction nor distortion are enabled

com.unity.render-pipelines.high-definition/Runtime/Lighting/LightLoop/LightLoopDef.hlsl

@@ -126,6 +126,9 @@ float4 SampleEnv(LightLoopContext lightLoopContext, int index, float3 texCoord,
         color.rgb = SampleSkyTexture(texCoord, lod, sliceIdx).rgb;
     }
 
+    // Planar, Reflection Probes and Sky aren't pre-expose, so best to clamp to max16 here in case of inf
+    color.rgb = ClampToFloat16Max(color.rgb);
+
     return color;
 }
 

com.unity.render-pipelines.high-definition/Runtime/Lighting/Shadow/ScreenSpaceShadows.shader

@@ -7,6 +7,7 @@ Shader "Hidden/HDRP/ScreenSpaceShadows"
         #pragma target 4.5
         #pragma only_renderers d3d11 playstation xboxone vulkan metal switch
         #include "Packages/com.unity.render-pipelines.core/ShaderLibrary/Common.hlsl"
+        #include "Packages/com.unity.render-pipelines.core/ShaderLibrary/CommonLighting.hlsl"
         #include "Packages/com.unity.render-pipelines.high-definition/Runtime/Material/Builtin/BuiltinData.hlsl"
         #include "Packages/com.unity.render-pipelines.high-definition/Runtime/ShaderLibrary/ShaderVariables.hlsl"
         #include "Packages/com.unity.render-pipelines.high-definition/Runtime/Material/NormalBuffer.hlsl"

com.unity.render-pipelines.high-definition/Runtime/PostProcessing/PostProcessSystem.cs

@@ -351,15 +351,26 @@ public void BeginFrame(CommandBuffer cmd, HDCamera camera, HDRenderPipeline hdIn
             }
             else
             {
-                if (IsExposureFixed())
+                // Fix exposure is store in Exposure Textures at the beginning of the frame as there is no need for color buffer
+                // Dynamic exposure (Auto, curve) is store in Exposure Textures at the end of the frame (as it rely on color buffer)
+                // Texture current and previous are swapped at the beginning of the frame.
+                bool isFixedExposure = IsExposureFixed();
+                if (isFixedExposure)
                 {
                     using (new ProfilingScope(cmd, ProfilingSampler.Get(HDProfileId.FixedExposure)))
                     {
                         DoFixedExposure(cmd, camera);
                     }
                 }
 
-                cmd.SetGlobalTexture(HDShaderIDs._ExposureTexture, GetExposureTexture(camera));
+                // Note: GetExposureTexture(camera) must be call AFTER the call of DoFixedExposure to be correctly taken into account
+                // When we use Dynamic Exposure and we reset history we can't use pre-exposure (as there is no information)
+                // For this reasons we put neutral value at the beginning of the frame in Exposure textures and
+                // apply processed exposure from color buffer at the end of the Frame, only for a single frame.
+                // After that we re-use the pre-exposure system
+                RTHandle currentExposureTexture = (camera.resetPostProcessingHistory && !isFixedExposure) ? m_EmptyExposureTexture : GetExposureTexture(camera);
+
+                cmd.SetGlobalTexture(HDShaderIDs._ExposureTexture, currentExposureTexture);
                 cmd.SetGlobalTexture(HDShaderIDs._PrevExposureTexture, GetPreviousExposureTexture(camera));
             }
         }
@@ -464,9 +475,9 @@ void PoolSource(ref RTHandle src, RTHandle dst)
                             cmd.DispatchCompute(cs, kernel, (camera.actualWidth + 7) / 8, (camera.actualHeight + 7) / 8, camera.viewCount);
 
                             PoolSource(ref source, destination);
+                        }
                     }
                 }
-                }
 
                 if (m_PostProcessEnabled)
                 {
@@ -846,9 +857,9 @@ void DoDynamicExposure(CommandBuffer cmd, HDCamera camera, RTHandle colorBuffer)
 
             if (camera.resetPostProcessingHistory)
             {
-                kernel = cs.FindKernel("KReset");
-                cmd.SetComputeTextureParam(cs, kernel, HDShaderIDs._OutputTexture, prevExposure);
-                cmd.DispatchCompute(cs, kernel, 1, 1, 1);
+                // For Dynamic Exposure, we need to undo the pre-exposure from the color buffer to calculate the correct one
+                // When we reset history we must setup neutral value
+                prevExposure = m_EmptyExposureTexture; // Use neutral texture
             }
 
             m_ExposureVariants[0] = 1; // (int)exposureSettings.luminanceSource.value;