Add volumetric bool

ScriptableRenderPipeline/HDRenderPipeline/HDRP/Editor/RenderLoopSettings/RenderPipelineSettingsUI.cs

             EditorGUILayout.PropertyField(d.supportMotionVectors, _.GetContent("Support Motion Vectors"));
             EditorGUILayout.PropertyField(d.supportStereo, _.GetContent("Support Stereo Rendering"));
             EditorGUILayout.PropertyField(d.enableUltraQualitySSS, _.GetContent("Increase SSS Sample Count"));
+            EditorGUILayout.PropertyField(d.supportVolumetric, _.GetContent("Support volumetric"));
             --EditorGUI.indentLevel;
         }
     }

ScriptableRenderPipeline/HDRenderPipeline/HDRP/Editor/RenderLoopSettings/SerializedRenderPipelineSettings.cs

         public SerializedProperty supportMotionVectors;
         public SerializedProperty supportStereo;
         public SerializedProperty enableUltraQualitySSS;
+        public SerializedProperty supportVolumetric;
 
         public SerializedGlobalLightLoopSettings lightLoopSettings;
         public SerializedShadowInitParameters shadowInitParams;
             supportMotionVectors = root.Find((RenderPipelineSettings s) => s.supportMotionVectors);
             supportStereo = root.Find((RenderPipelineSettings s) => s.supportStereo);
             enableUltraQualitySSS = root.Find((RenderPipelineSettings s) => s.enableUltraQualitySSS);
+            supportVolumetric = root.Find((RenderPipelineSettings s) => s.supportVolumetric);
 
             lightLoopSettings = new SerializedGlobalLightLoopSettings(root.Find((RenderPipelineSettings s) => s.lightLoopSettings));
             shadowInitParams = new SerializedShadowInitParameters(root.Find((RenderPipelineSettings s) => s.shadowInitParams));

ScriptableRenderPipeline/HDRenderPipeline/HDRP/RenderPipeline/FrameSettings.cs

         public bool enableSSAO = true;
         public bool enableSubsurfaceScattering = true;
         public bool enableTransmission = true;  // Caution: this is only for debug, it doesn't save the cost of Transmission execution
+        public bool enableVolumetric = true;
 
         // Setup by system
         public float diffuseGlobalDimmer = 1.0f;
             aggregate.enableSSAO = srcFrameSettings.enableSSAO && renderPipelineSettings.supportSSAO;
             aggregate.enableSubsurfaceScattering = camera.cameraType != CameraType.Reflection && srcFrameSettings.enableSubsurfaceScattering && renderPipelineSettings.supportSubsurfaceScattering;
             aggregate.enableTransmission = srcFrameSettings.enableTransmission;
+            aggregate.enableVolumetric = srcFrameSettings.enableVolumetric && renderPipelineSettings.supportVolumetric;
+
+            // TODO: Add support of volumetric in planar reflection
+            if (camera.cameraType == CameraType.Reflection)
+                aggregate.enableVolumetric = false;
 
             // We have to fall back to forward-only rendering when scene view is using wireframe rendering mode
             // as rendering everything in wireframe + deferred do not play well together
                 aggregate.enablePostprocess = false;
                 aggregate.enableStereo = false;
                 aggregate.enableShadowMask = false;
+                aggregate.enableVolumetric = false;
             }
 
             LightLoopSettings.InitializeLightLoopSettings(camera, aggregate, renderPipelineSettings, srcFrameSettings, ref aggregate.lightLoopSettings);

ScriptableRenderPipeline/HDRenderPipeline/HDRP/RenderPipeline/RenderPipelineSettings.cs

         public bool supportSubsurfaceScattering = true;
         public bool supportForwardOnly = false;
         public bool enableUltraQualitySSS = false;
+        public bool supportVolumetric = true;
 
         // Engine
         public bool         supportDBuffer = false;