Fixed two issues with sky static lighting.

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

@@ -50,6 +50,8 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 - Fixed issue when undoing a change in diffuse profile list after deleting the volume profile.
 - Fixed custom pass re-ordering and removing.
 - Fixed TAA issue and hardware dynamic resolution.
+- 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
 - Preparation pass for RTSSShadows to be supported by render graph.

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

@@ -497,8 +497,7 @@ 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

@@ -393,7 +393,7 @@ partial struct FrameSettings
                 (uint)FrameSettingsField.MotionVectors, // Enable/disable whole motion vectors pass (Camera + Object).
                 (uint)FrameSettingsField.ObjectMotionVectors,
                 (uint)FrameSettingsField.Decals,
-                (uint)FrameSettingsField.DecalLayers,                
+                (uint)FrameSettingsField.DecalLayers,
                 (uint)FrameSettingsField.Refraction, // Depends on DepthPyramid - If not enable, just do a copy of the scene color (?) - how to disable refraction ?
                 (uint)FrameSettingsField.Distortion,
                 (uint)FrameSettingsField.Postprocess,
@@ -467,7 +467,7 @@ partial struct FrameSettings
                 (uint)FrameSettingsField.MotionVectors, // Enable/disable whole motion vectors pass (Camera + Object).
                 (uint)FrameSettingsField.ObjectMotionVectors,
                 (uint)FrameSettingsField.Decals,
-                (uint)FrameSettingsField.DecalLayers,  
+                (uint)FrameSettingsField.DecalLayers,
                 //(uint)FrameSettingsField.Refraction, // Depends on DepthPyramid - If not enable, just do a copy of the scene color (?) - how to disable refraction ?
                 //(uint)FrameSettingsField.Distortion,
                 //(uint)FrameSettingsField.Postprocess,
@@ -797,6 +797,13 @@ internal static void Sanitize(ref FrameSettings sanitizedFrameSettings, Camera c
             sanitizedFrameSettings.bitDatas[(int)FrameSettingsField.FPTLForForwardOpaque] &= !msaa;
 
             sanitizedFrameSettings.bitDatas[(int)FrameSettingsField.ProbeVolume] &= renderPipelineSettings.supportProbeVolume && (ShaderConfig.s_ProbeVolumesEvaluationMode != ProbeVolumesEvaluationModes.Disabled);
+
+            // 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

@@ -735,6 +735,18 @@ public void UpdateEnvironment(  HDCamera                hdCamera,
                 m_BuiltinParameters.skySettings = skyContext.skySettings;
                 m_BuiltinParameters.cloudLayer = skyContext.cloudLayer;
 
+                // 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;
 
@@ -753,6 +765,7 @@ public void UpdateEnvironment(  HDCamera                hdCamera,
                 {
                     using (new ProfilingScope(cmd, ProfilingSampler.Get(HDProfileId.UpdateSkyEnvironment)))
                     {
+                        // Debug.Log("Update Sky Lighting");
                         RenderSkyToCubemap(skyContext);
 
                         if (updateAmbientProbe)
@@ -832,7 +845,7 @@ public void UpdateEnvironment(HDCamera hdCamera, ScriptableRenderContext renderC
             {
                 m_StaticLightingSky.skySettings = staticLightingSky != null ? staticLightingSky.skySettings : null;
                 m_StaticLightingSky.cloudLayer = staticLightingSky != null ? staticLightingSky.cloudLayer : 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;
             }