Fixed two issues with sky static lighting. #1775

Author: JulienIgnace-Unity

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

@@ -53,6 +53,8 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 - Fixed an issue where opening the look dev window with the light theme would make the window blink and eventually crash unity.
 - Fixed a serialization issue, preventing quality level parameters to undo/redo and update scene view on change.
 - Fixed an issue where look dev lighting would go black when a new scene is loaded.
+- Fixed a static lighting flickering issue caused by having an active planar probe in the scene while rendering inspector preview.
+- Fixed an issue where even when set to OnDemand, the sky lighting would still be updated when changing sky parameters.
 
 ### Changed
 - Changed extensions of shader CAS include files.

com.unity.render-pipelines.high-definition/Runtime/Lighting/Reflection/HDProbe.cs

@@ -437,8 +437,7 @@ internal void ForceRenderingNextUpdate()
 
         void UpdateProbeName()
         {
-            // TODO: ask if this is ok:
-            if (settings.type == ProbeSettings.ProbeType.PlanarProbe)
+            if (settings.type == ProbeSettings.ProbeType.ReflectionProbe)
             {
                 for (int i = 0; i < 6; i++)
                     probeName[i] = $"Reflection Probe RenderCamera ({name}: {(CubemapFace)i})";

com.unity.render-pipelines.high-definition/Runtime/RenderPipeline/Settings/FrameSettings.cs

@@ -699,6 +699,13 @@ internal static void Sanitize(ref FrameSettings sanitizedFrameSettings, Camera c
             // When MSAA is enabled we disable Fptl as it become expensive compare to cluster
             // In HD, MSAA is only supported for forward only rendering, no MSAA in deferred mode (for code complexity reasons)
             sanitizedFrameSettings.bitDatas[(int)FrameSettingsField.FPTLForForwardOpaque] &= !msaa;
+
+            // We disable reflection probes and planar reflections in regular preview rendering for two reasons.
+            // - Performance: Realtime reflection are 99% not necessary in previews
+            // - Static lighting consistency: When rendering a planar probe from a preview camera it may induce a recomputing of the static lighting
+            //   but with the preview lights which are different from the ones in the scene and will change the result inducing flickering.
+            sanitizedFrameSettings.bitDatas[(int)FrameSettingsField.ReflectionProbe] &= !preview;
+            sanitizedFrameSettings.bitDatas[(int)FrameSettingsField.PlanarProbe] &= !preview;
         }
 
         /// <summary>Aggregation is default with override of the renderer then sanitized depending on supported features of hdrpasset.</summary>

com.unity.render-pipelines.high-definition/Runtime/Sky/SkyManager.cs

@@ -727,6 +727,18 @@ public void UpdateEnvironment(  HDCamera                hdCamera,
                 m_BuiltinParameters.frameIndex = frameIndex;
                 m_BuiltinParameters.skySettings = skyContext.skySettings;
 
+                // When update is not requested and the context is already valid (ie: already computed at least once),
+                // we need to early out in two cases:
+                // - updateMode is "OnDemand" in which case we never update unless explicitly requested
+                // - updateMode is "Realtime" in which case we only update if the time threshold for realtime update is passed.
+                if (IsCachedContextValid(skyContext) && !updateRequired)
+                {
+                    if (skyContext.skySettings.updateMode.value == EnvironmentUpdateMode.OnDemand)
+                        return;
+                    else if (skyContext.skySettings.updateMode.value == EnvironmentUpdateMode.Realtime && skyContext.currentUpdateTime < skyContext.skySettings.updatePeriod.value)
+                        return;
+                }
+
                 int skyHash = ComputeSkyHash(hdCamera, skyContext, sunLight, ambientMode, staticSky);
                 bool forceUpdate = updateRequired;
 
@@ -745,6 +757,7 @@ public void UpdateEnvironment(  HDCamera                hdCamera,
                 {
                     using (new ProfilingScope(cmd, ProfilingSampler.Get(HDProfileId.UpdateSkyEnvironment)))
                     {
+                        // Debug.Log("Update Sky Lighting");
                         RenderSkyToCubemap(skyContext);
 
                         if (updateAmbientProbe)
@@ -823,7 +836,7 @@ public void UpdateEnvironment(HDCamera hdCamera, ScriptableRenderContext renderC
             if ((ambientMode == SkyAmbientMode.Static || forceStaticUpdate) && hdCamera.camera.cameraType != CameraType.Preview)
             {
                 m_StaticLightingSky.skySettings = staticLightingSky != null ? staticLightingSky.skySettings : null;
-                UpdateEnvironment(hdCamera, renderContext, m_StaticLightingSky, sunLight, m_StaticSkyUpdateRequired, true, true, SkyAmbientMode.Static, frameIndex, cmd);
+                UpdateEnvironment(hdCamera, renderContext, m_StaticLightingSky, sunLight, m_StaticSkyUpdateRequired || m_UpdateRequired, true, true, SkyAmbientMode.Static, frameIndex, cmd);
                 m_StaticSkyUpdateRequired = false;
             }