Correct the blending behavior of atmospheric scattering

Assets/ScriptableRenderLoop/HDRenderLoop/Sky/Resources/SkyHDRI.shader

 
             #pragma multi_compile _ ATMOSPHERICS_OCCLUSION_FULLSKY
             #pragma multi_compile _ ATMOSPHERICS_DEBUG
+            #pragma multi_compile _ PERFORM_SKY_OCCLUSION_TEST
 
             #include "Color.hlsl"
             #include "Common.hlsl"
                 float3 rotDirY = float3(sinPhi, 0, cosPhi);
                 dir = float3(dot(rotDirX, dir), dir.y, dot(rotDirY, dir));
 
-                float3 skyDome = ClampToFloat16Max(SAMPLE_TEXTURECUBE_LOD(_Cubemap, sampler_Cubemap, dir, 0).rgb * exp2(_SkyParam.x) * _SkyParam.y);
-
-                // Get the depth value of the scene, or use 0.01 otherwise.
-                float  rawDepth   = max(LOAD_TEXTURE2D(_CameraDepthTexture, coord.unPositionSS).r, 0.01);
-                float3 positionWS = UnprojectToWorld(rawDepth, coord.positionSS, _InvViewProjMatrix);
+                // If the sky box is too far away (depth set to 0), the resulting look is too foggy.
+                const float skyDepth = 0.01;
-                // Do not perform blending with the environment map if the sky is occluded.
-                float skyDomeWeight = (rawDepth > 0.01) ? 0.0 : 1.0;
+                #ifdef PERFORM_SKY_OCCLUSION_TEST
+                    // Determine whether the sky is occluded by the scene geometry.
+                    // Do not perform blending with the environment map if the sky is occluded.
+                    float rawDepth     = max(skyDepth, LOAD_TEXTURE2D(_CameraDepthTexture, coord.unPositionSS).r);
+                    float skyTexWeight = (rawDepth > skyDepth) ? 0.0 : 1.0;
+                #else
+                    float rawDepth     = skyDepth;
+                    float skyTexWeight = 1.0;
+                #endif
+
+                float3 positionWS = UnprojectToWorld(rawDepth, coord.positionSS, _InvViewProjMatrix);
 
                 float4 c1, c2, c3;
                 VolundTransferScatter(positionWS, c1, c2, c3);
                     }
                 #endif
 
-                // Blend with the color of the scene.
-                return float4(skyDome * (skyDomeWeight * extinction) + scatter, 0.0);
+                float3 skyColor = ClampToFloat16Max(SAMPLE_TEXTURECUBE_LOD(_Cubemap, sampler_Cubemap, dir, 0).rgb * exp2(_SkyParam.x) * _SkyParam.y);
+
+                return float4(skyColor * (skyTexWeight * extinction) + scatter, 0.0);
             }
 
             ENDHLSL

Assets/ScriptableRenderLoop/HDRenderLoop/Sky/SkyRenderer.cs

                 eyeVectorData[3] = new Vector3(direction0.x, direction0.y, direction0.z).normalized;
                 eyeVectorData[2] = new Vector3(direction1.x, direction1.y, direction1.z).normalized;
                 eyeVectorData[1] = new Vector3(direction2.x, direction2.y, direction2.z).normalized;
-                eyeVectorData[0] = new Vector3(direction3.x, direction3.y, direction3.z).normalized;                
+                eyeVectorData[0] = new Vector3(direction3.x, direction3.y, direction3.z).normalized;
             }
             else
             {
                             new Vector3(0.0f, 0.0f, 1.0f),
                             new Vector3(0.0f, 0.0f, -1.0f),
                         };
-            
+
             Vector3[] UpVectorList = {
                             new Vector3(0.0f, 1.0f, 0.0f),
                             new Vector3(0.0f, 1.0f, 0.0f),
         {
             Mesh skyMesh = BuildSkyMesh(camera, forceUVBottom);
 
+            Shader.EnableKeyword("PERFORM_SKY_OCCLUSION_TEST");
+
             m_RenderSkyPropertyBlock.SetTexture("_Cubemap", skyParameters.skyHDRI);
             m_RenderSkyPropertyBlock.SetVector("_SkyParam", new Vector4(skyParameters.exposure, skyParameters.multiplier, skyParameters.rotation, 0.0f));
             m_RenderSkyPropertyBlock.SetMatrix("_InvViewProjMatrix", Utilities.GetViewProjectionMatrix(camera).inverse);
 
         private void RenderSkyToCubemap(SkyParameters skyParameters, RenderTexture target, RenderLoop renderLoop)
         {
+            Shader.DisableKeyword("PERFORM_SKY_OCCLUSION_TEST");
+
             for (int i = 0; i < 6; ++i)
             {
                 Utilities.SetRenderTarget(renderLoop, target, 0, (CubemapFace)i);