Add shader stripper support for decal variant + update HDRP asset

com.unity.render-pipelines.high-definition/HDRP/Editor/Material/BaseShaderPreprocessor.cs

         protected ShaderKeyword m_TileLighting;
         protected ShaderKeyword m_ClusterLighting;
         protected ShaderKeyword m_LodFadeCrossFade;
+        protected ShaderKeyword m_Decals3RT;
+        protected ShaderKeyword m_Decals4RT;
 
         public BaseShaderPreprocessor()
         {
             m_ClusterLighting = new ShaderKeyword("USE_CLUSTERED_LIGHTLIST");
             m_LodFadeCrossFade = new ShaderKeyword("LOD_FADE_CROSSFADE");
+            m_Decals3RT = new ShaderKeyword("_DECALS_3RT");
+            m_Decals4RT = new ShaderKeyword("_DECALS_4RT");
         }
 
         public virtual void AddStripperFuncs(Dictionary<string, VariantStrippingFunc> stripperFuncs) {}
                 return true;
 
             if (inputData.shaderKeywordSet.IsEnabled(m_LodFadeCrossFade) && !hdrpAsset.renderPipelineSettings.supportDitheringCrossFade)
+                return true;
+
+            // Decal case
+            // If no decal, remove decal variant
+            if ((inputData.shaderKeywordSet.IsEnabled(m_Decals3RT) || inputData.shaderKeywordSet.IsEnabled(m_Decals4RT)) && !hdrpAsset.renderPipelineSettings.supportDecals)
+                return true;
+
+            // If decal but with 4RT remove 3RT variant and vice versa
+            if (inputData.shaderKeywordSet.IsEnabled(m_Decals3RT) && hdrpAsset.renderPipelineSettings.decalSettings.perChannelMask)
+                return true;
+ 
+            if (inputData.shaderKeywordSet.IsEnabled(m_Decals4RT) && !hdrpAsset.renderPipelineSettings.decalSettings.perChannelMask)
                 return true;
 
             return false;

com.unity.render-pipelines.high-definition/HDRP/HDRenderPipelineAsset.asset

   m_Script: {fileID: 11500000, guid: 0cf1dab834d4ec34195b920ea7bbf9ec, type: 3}
   m_Name: HDRenderPipelineAsset
   m_EditorClassIdentifier: 
-  version: 1
+  m_Version: 1
   m_RenderPipelineResources: {fileID: 11400000, guid: 3ce144cff5783da45aa5d4fdc2da14b7, type: 2}
   m_FrameSettings:
     enableShadow: 1
     enableTransparentPrepass: 1
     enableMotionVectors: 1
     enableObjectMotionVectors: 1
-    enableDBuffer: 1
+    enableDecals: 1
     enableRoughRefraction: 1
     enableTransparentPostpass: 1
     enableDistortion: 1
     increaseResolutionOfVolumetrics: 0
     supportRuntimeDebugDisplay: 1
     supportDitheringCrossFade: 1
-    supportDBuffer: 1
+    supportDecals: 1
     supportMSAA: 0
     msaaSampleCount: 1
     supportMotionVectors: 1
       drawDistance: 1000
       atlasWidth: 4096
       atlasHeight: 4096
+      perChannelMask: 0
   allowShaderVariantStripping: 1
   diffusionProfileSettings: {fileID: 11400000, guid: 404820c4cf36ad944862fa59c56064f0, type: 2}

com.unity.render-pipelines.high-definition/HDRP/RenderPipeline/HDRenderPipeline.cs

                     m_ReflectionProbeCullResults.Cull();
 
                     m_DbufferManager.enableDBuffer = false;
-                    using (new ProfilingSample(cmd, "DBufferPrepareDrawData", CustomSamplerId.DBufferPrepareDrawData.GetSampler()))
+                    if (hdCamera.frameSettings.enableDecals)
-                        if (hdCamera.frameSettings.enableDecals)
+                        using (new ProfilingSample(cmd, "DBufferPrepareDrawData", CustomSamplerId.DBufferPrepareDrawData.GetSampler()))
                         {
                             DecalSystem.instance.EndCull();
                             m_DbufferManager.enableDBuffer = true;              // mesh decals are renderers managed by c++ runtime and we have no way to query if any are visible, so set to true