Fixed a shader warning in the volumetric clouds combine file. (#6410)

* - Fixed a shader warning in the volumetric clouds combine file.

* more warnings

Author: anisunity

com.unity.render-pipelines.high-definition/CHANGELOG.md

@@ -38,6 +38,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 - Fixed for screen space overlay rendered by camera when HDR is disabled.
 - Fixed dirtiness handling in path tracing, when using multiple cameras at once (case 1376940).
 - Fixed taa jitter for after post process materials (case 1380967).
+- Fixed a shader warning in the volumetric clouds combine file.
 
 ## [13.1.2] - 2021-11-05
 

com.unity.render-pipelines.high-definition/Runtime/Lighting/VolumetricLighting/VolumetricCloudsCombine.shader

@@ -138,7 +138,7 @@ Shader "Hidden/HDRP/VolumetricCloudsCombine"
             float4 Frag(Varyings input) : SV_Target
             {
                 // Points towards the camera
-                float3 viewDirWS = -normalize(mul(float4(input.positionCS.xy * (float)_Mipmap, 1.0, 1.0), _PixelCoordToViewDirWS));
+                float3 viewDirWS = -normalize(mul(float4(input.positionCS.xy * (float)_Mipmap, 1.0, 1.0), _PixelCoordToViewDirWS).xyz);
                 // Fetch the clouds
                 return SAMPLE_TEXTURECUBE_LOD(_VolumetricCloudsTexture, s_linear_clamp_sampler, viewDirWS, _Mipmap);
             }
@@ -157,7 +157,7 @@ Shader "Hidden/HDRP/VolumetricCloudsCombine"
             float4 Frag(Varyings input) : SV_Target
             {
                 // Construct the view direction
-                float3 viewDirWS = -normalize(mul(float4(input.positionCS.xy * (float)_Mipmap, 1.0, 1.0), _PixelCoordToViewDirWS));
+                float3 viewDirWS = -normalize(mul(float4(input.positionCS.xy * (float)_Mipmap, 1.0, 1.0), _PixelCoordToViewDirWS).xyz);
                 // Fetch the clouds
                 float4 clouds = SAMPLE_TEXTURECUBE_LOD(_VolumetricCloudsTexture, s_linear_clamp_sampler, viewDirWS, _Mipmap);
                 // Inverse the exposure
@@ -183,7 +183,7 @@ Shader "Hidden/HDRP/VolumetricCloudsCombine"
             float4 Frag(Varyings input) : SV_Target
             {
                 // Construct the view direction
-                float3 viewDirWS = -normalize(mul(float4(input.positionCS.xy * (float)_Mipmap, 1.0, 1.0), _PixelCoordToViewDirWS));
+                float3 viewDirWS = -normalize(mul(float4(input.positionCS.xy * (float)_Mipmap, 1.0, 1.0), _PixelCoordToViewDirWS).xyz);
                 // Fetch the clouds
                 float4 clouds = SAMPLE_TEXTURECUBE_LOD(_VolumetricCloudsTexture, s_linear_clamp_sampler, viewDirWS, _Mipmap);
                 // Inverse the exposure