Fix camera editor preview

ScriptableRenderPipeline/HDRenderPipeline/HDRP/Camera/HDAdditionalCameraData.cs

         public Color backgroundColorHDR = new Color(0.025f, 0.07f, 0.19f, 0.0f);
         public bool clearDepth = true;
 
-        public RenderingPath    renderingPath;
+        public RenderingPath renderingPath;
-        public LayerMask        volumeLayerMask = -1;
+        public LayerMask volumeLayerMask = -1;
 
         // Physical parameters
         public float aperture = 8f;
         // we create a runtime copy (m_ActiveFrameSettings that is used, and any parametrization is done on serialized frameSettings)
         [SerializeField]
         [FormerlySerializedAs("serializedFrameSettings")]
-        FrameSettings    m_FrameSettings = new FrameSettings(); // Serialize frameSettings
+        FrameSettings m_FrameSettings = new FrameSettings(); // Serialize frameSettings
 
         // Not serialized, visible only in the debug windows
         FrameSettings m_FrameSettingsRuntime = new FrameSettings();
         // Use for debug windows
         // When camera name change we need to update the name in DebugWindows.
         // This is the purpose of this class
-        bool    m_IsDebugRegistered = false;
-        string  m_CameraRegisterName;
+        bool m_IsDebugRegistered = false;
+        string m_CameraRegisterName;
+
+        // When we are a preview, there is no way inside Unity to make a disctinctoin between camera preview and material preview.
+        // This property allow to say that we are an editor camera preview when the type is preview.
+        public bool isEditorCameraPreview { get; set; }
 
         // This is the function use outside to access FrameSettings. It return the current state of FrameSettings for the camera
         // taking into account the customization via the debug menu

ScriptableRenderPipeline/HDRenderPipeline/HDRP/Editor/Camera/HDCameraEditor.Handlers.cs

             EditorUtility.CopySerialized(cameraData, m_PreviewAdditionalCameraData);
             var layer = c.GetComponent<PostProcessLayer>() ?? ComponentSingleton<PostProcessLayer>.instance;
             EditorUtility.CopySerialized(layer, m_PreviewPostProcessLayer);
-            m_PreviewCamera.cameraType = CameraType.Preview;
 
             var previewTexture = GetPreviewTextureWithSize((int)previewSize.x, (int)previewSize.y);
             m_PreviewCamera.targetTexture = previewTexture;

ScriptableRenderPipeline/HDRenderPipeline/HDRP/Editor/Camera/HDCameraEditor.cs

             m_PreviewCamera.enabled = false;
             m_PreviewCamera.cameraType = CameraType.Preview; // Must be init before adding HDAdditionalCameraData
             m_PreviewAdditionalCameraData = m_PreviewCamera.gameObject.AddComponent<HDAdditionalCameraData>();
+            // Say that we are a camera editor preview and not just a regular preview
+            m_PreviewAdditionalCameraData.isEditorCameraPreview = true;
             m_PreviewPostProcessLayer = m_PreviewCamera.gameObject.AddComponent<PostProcessLayer>();
         }
 

ScriptableRenderPipeline/HDRenderPipeline/HDRP/HDRenderPipeline.cs

                         (hdCamera.clearColorMode == HDAdditionalCameraData.ClearColorMode.Sky && !m_SkyManager.IsVisualSkyValid()) ||
                         // Special handling for Preview we force to clear with background color (i.e black)
                         // Note that the sky use in this case is the last one setup. If there is no scene or game, there is no sky use as reflection in the preview
-                        hdCamera.camera.cameraType == CameraType.Preview
+                        HDUtils.IsRegularPreviewCamera(hdCamera.camera)
                         )
                     {
                         Color clearColor = hdCamera.backgroundColorHDR;

ScriptableRenderPipeline/HDRenderPipeline/HDRP/HDUtils.cs

             Vector2 mousePixelCoord = MousePositionDebug.instance.GetMouseClickPosition(camera.screenSize.y);
             return new Vector4(mousePixelCoord.x, mousePixelCoord.y, camera.viewportScale.x * mousePixelCoord.x / camera.screenSize.x, camera.viewportScale.y * mousePixelCoord.y / camera.screenSize.y);
         }
+
+        // This function check if camera is a CameraPreview, then check if this preview is a regular preview (i.e not a preview from the camera editor)
+        public static bool IsRegularPreviewCamera(Camera camera)
+        {
+            var additionalCameraData = camera.GetComponent<HDAdditionalCameraData>();
+            return camera.cameraType == CameraType.Preview && ((additionalCameraData == null) || (additionalCameraData && !additionalCameraData.isEditorCameraPreview));
+        }
     }
 }

ScriptableRenderPipeline/HDRenderPipeline/HDRP/RenderPipeline/FrameSettings.cs

             aggregate.ConfigureMSAADependentSettings();
             aggregate.ConfigureStereoDependentSettings();
 
-            // Note: Camera preview is both the preview of a material and the preview of a camera (Unity doesn't make a distinction here)
-            if (camera.cameraType == CameraType.Preview)
+            // Disable various option for the preview except if we are a Camera Editor preview
+            if (HDUtils.IsRegularPreviewCamera(camera))
-                // remove undesired feature in preview
                 aggregate.enableShadow = false;
                 aggregate.enableContactShadows = false;
                 aggregate.enableSSR = false;

ScriptableRenderPipeline/HDRenderPipeline/HDRP/Sky/SkyManager.cs

             }
         }
 
-        public void UpdateCurrentSkySettings(HDCamera camera)
+        public void UpdateCurrentSkySettings(HDCamera hdCamera)
-            if (camera.camera.cameraType == CameraType.Preview)
+            if (HDUtils.IsRegularPreviewCamera(hdCamera.camera))
             {
                 m_VisualSky.skySettings = GetDefaultPreviewSkyInstance();
             }
 
             // Update needs to happen before testing if the component is active other internal data structure are not properly updated yet.
-            VolumeManager.instance.Update(m_LightingOverrideVolumeStack, camera.camera.transform, m_LightingOverrideLayerMask);
+            VolumeManager.instance.Update(m_LightingOverrideVolumeStack, hdCamera.camera.transform, m_LightingOverrideLayerMask);
             if(VolumeManager.instance.IsComponentActiveInMask<VisualEnvironment>(m_LightingOverrideLayerMask))
             {
                 SkySettings newSkyOverride = GetSkySetting(m_LightingOverrideVolumeStack);