Fix sky in preview and fog in sceneView

ScriptableRenderPipeline/Core/CoreRP/Utilities/CoreUtils.cs

         {
             string msg = "AR/VR devices are not supported, no rendering will occur";
             DisplayUnsupportedMessage(msg);
-        }        
+        }
 
         // Returns 'true' if "Animated Materials" are enabled for the view associated with the given camera.
         public static  bool AreAnimatedMaterialsEnabled(Camera camera)
                     }
                 }
             }
-            
+
             // TODO: how to handle reflection views? We don't know the parent window they are being rendered into,
             // so we don't know whether we can animate them...
             //
         #endif
 
             return animateMaterials;
+        }
+
+        public static bool IsSceneViewFogEnabled(Camera camera)
+        {
+            bool fogEnable = true;
+
+#if UNITY_EDITOR
+            fogEnable = Application.isPlaying;
+
+            if (camera.cameraType == CameraType.SceneView)
+            {
+                fogEnable = false;
+
+                // Determine whether the "Animated Materials" checkbox is checked for the current view.
+                foreach (UnityEditor.SceneView sv in Resources.FindObjectsOfTypeAll(typeof(UnityEditor.SceneView)))
+                {
+                    if (sv.camera == camera && sv.sceneViewState.showFog)
+                    {
+                        fogEnable = true;
+                        break;
+                    }
+                }
+            }
+#endif
+
+            return fogEnable;
         }
     }
 }

ScriptableRenderPipeline/HDRenderPipeline/CHANGELOG.md

 - 
 
 ### Bug fixes
+- Fix fog flags in scene view is now taken into account
+- Fix sky in preview windows that were disappearing after a load of a new level
 - Fix numerical issues in IntersectRayAABB().
 - Fix alpha blending of volumetric lighting with transparent objects.
 - Fix the near plane of the V-Buffer causing out-of-bounds look-ups in the clustered data structure.

ScriptableRenderPipeline/HDRenderPipeline/HDRP/RenderPipeline/FrameSettings.cs

             aggregate.enableObjectMotionVectors = camera.cameraType != CameraType.Reflection && srcFrameSettings.enableObjectMotionVectors && renderPipelineSettings.supportMotionVectors;
             aggregate.enableDBuffer = srcFrameSettings.enableDBuffer && renderPipelineSettings.supportDBuffer;
             aggregate.enableAtmosphericScattering = srcFrameSettings.enableAtmosphericScattering;
+            // We must take care of the scene view fog flags in the editor
+            if (!CoreUtils.IsSceneViewFogEnabled(camera))
+                aggregate.enableAtmosphericScattering = false;
             aggregate.enableRoughRefraction = srcFrameSettings.enableRoughRefraction;
             aggregate.enableTransparentPostpass = srcFrameSettings.enableTransparentPostpass;
             aggregate.enableDistortion = camera.cameraType != CameraType.Reflection && srcFrameSettings.enableDistortion;

ScriptableRenderPipeline/HDRenderPipeline/HDRP/Sky/SkyManager.cs

 #if UNITY_EDITOR
             if (camera.camera.cameraType == CameraType.Preview)
             {
-                m_VisualSky.skySettings = m_DefaultPreviewSky;
+                m_VisualSky.skySettings = GetDefaultPreviewSkyInstance();
             }
 #endif
 
             cmd.SetGlobalFloat(HDShaderIDs._SkyTextureMipCount, mipCount);
         }
 
+#if UNITY_EDITOR
+        ProceduralSky GetDefaultPreviewSkyInstance()
+        {
+            if (m_DefaultPreviewSky == null)
+            {
+                m_DefaultPreviewSky = ScriptableObject.CreateInstance<ProceduralSky>();
+            }
+
+            return m_DefaultPreviewSky;
+        }
+#endif
+
         public void Build(HDRenderPipelineAsset hdAsset, IBLFilterGGX iblFilterGGX)
         {
             m_BakingSkyRenderingContext = new SkyRenderingContext(iblFilterGGX, (int)hdAsset.renderPipelineSettings.lightLoopSettings.skyReflectionSize, false);
 
             m_LightingOverrideVolumeStack = VolumeManager.instance.CreateStack();
             m_LightingOverrideLayerMask = hdAsset.renderPipelineSettings.lightLoopSettings.skyLightingOverrideLayerMask;
-
-#if UNITY_EDITOR
-            m_DefaultPreviewSky = ScriptableObject.CreateInstance<ProceduralSky>();
-#endif
+
+#if UNITY_EDITOR
+            CoreUtils.Destroy(m_DefaultPreviewSky);
+#endif
             CoreUtils.Destroy(m_StandardSkyboxMaterial);
             CoreUtils.Destroy(m_BlitCubemapMaterial);
             CoreUtils.Destroy(m_OpaqueAtmScatteringMaterial);