Enable volumetric fog by default

ScriptableRenderPipeline/HDRenderPipeline/HDRP/HDRenderPipeline.cs

 
             m_SkyManager.RenderSky(hdCamera, m_LightLoop.GetCurrentSunLight(), m_CameraColorBuffer, m_CameraDepthStencilBuffer, m_CurrentDebugDisplaySettings, cmd);
 
-            if (visualEnv.fogType != FogType.None || m_VolumetricLightingSystem.preset != VolumetricLightingSystem.VolumetricLightingPreset.Off)
+            if (visualEnv.fogType != FogType.None)
                 m_SkyManager.RenderOpaqueAtmosphericScattering(cmd);
         }
 

ScriptableRenderPipeline/HDRenderPipeline/HDRP/Lighting/Volumetrics/VolumetricLighting.cs

     public void ResizeVBuffer(HDCamera camera, int screenWidth, int screenHeight)
     {
         if (preset == VolumetricLightingPreset.Off) return;
+        var visualEnvironment = VolumeManager.instance.stack.GetComponent<VisualEnvironment>();
+        if (visualEnvironment == null || visualEnvironment.fogType != FogType.Volumetric) return;
 
         long viewID = camera.GetViewID();
 
     public void PushGlobalParams(HDCamera camera, CommandBuffer cmd)
     {
         if (preset == VolumetricLightingPreset.Off) return;
+        var visualEnvironment = VolumeManager.instance.stack.GetComponent<VisualEnvironment>();
+        if (visualEnvironment == null || visualEnvironment.fogType != FogType.Volumetric) return;
 
         // Modify the near plane.
         // Warning: it can screw up the reprojection. However, we have to do it in order for clustered lighting to work correctly.
         DensityVolumeList densityVolumes = new DensityVolumeList();
 
         if (preset == VolumetricLightingPreset.Off) return densityVolumes;
-
-
-        if (visualEnvironment.fogType != FogType.Volumetric) return densityVolumes;
+        if (visualEnvironment == null || visualEnvironment.fogType != FogType.Volumetric) return densityVolumes;
 
         using (new ProfilingSample(cmd, "Prepare Visible Density Volume List"))
         {
     public void VolumeVoxelizationPass(DensityVolumeList densityVolumes, HDCamera camera, CommandBuffer cmd, FrameSettings settings)
     {
         if (preset == VolumetricLightingPreset.Off) return;
+        var visualEnvironment = VolumeManager.instance.stack.GetComponent<VisualEnvironment>();
+        if (visualEnvironment == null || visualEnvironment.fogType != FogType.Volumetric) return;
 
         using (new ProfilingSample(cmd, "Volume Voxelization"))
         {
             {
                 // Clear the render target instead of running the shader.
+                // Note: the clear must take the global fog into account!
-                // Use the workaround by running the full shader with 0 density.
+                // Use the workaround by running the full shader with 0 density
             }
 
             VBuffer vBuffer = FindVBuffer(camera.GetViewID());
     public void VolumetricLightingPass(HDCamera camera, CommandBuffer cmd, FrameSettings settings)
     {
         if (preset == VolumetricLightingPreset.Off) return;
+        var visualEnvironment = VolumeManager.instance.stack.GetComponent<VisualEnvironment>();
+        if (visualEnvironment == null || visualEnvironment.fogType != FogType.Volumetric) return;
-            var visualEnvironment = VolumeManager.instance.stack.GetComponent<VisualEnvironment>();
-
-            if (visualEnvironment.fogType != FogType.Volumetric)
-            {
-                // Clear the render target instead of running the shader.
-                // CoreUtils.SetRenderTarget(cmd, vBuffer.GetDensityBuffer(), ClearFlag.Color, CoreUtils.clearColorAllBlack);
-                // return;
-
-                // Clearing 3D textures does not seem to work!
-                // Use the workaround by running the full shader with 0 density.
-            }
-
             VBuffer vBuffer = FindVBuffer(camera.GetViewID());
             Debug.Assert(vBuffer != null);
 

ScriptableRenderPipeline/HDRenderPipeline/HDRP/ShaderConfig.cs

     {
         CameraRelativeRendering = 1, // Rendering sets the origin of the world to the position of the primary (scene view) camera
         UseDisneySSS = 1,            // Allow to chose between Burley Normalized Diffusion (Multi + Fix direction single scattering) or Jimenez diffusion approximation (Multiscattering only - More blurry) for Subsurface scattering
-        VolumetricLightingPreset = 0 // 0 = disabled, 1 = normal, 2 = ultra
+        VolumetricLightingPreset = 1 // 0 = disabled, 1 = normal, 2 = ultra
     };
 
     // Note: #define can't be use in include file in C# so we chose this way to configure both C# and hlsl

ScriptableRenderPipeline/HDRenderPipeline/HDRP/ShaderConfig.cs.hlsl

 //
 #define SHADEROPTIONS_CAMERA_RELATIVE_RENDERING (1)
 #define SHADEROPTIONS_USE_DISNEY_SSS (1)
-#define SHADEROPTIONS_VOLUMETRIC_LIGHTING_PRESET (0)
+#define SHADEROPTIONS_VOLUMETRIC_LIGHTING_PRESET (1)
 
 
 #endif