Add DECAL_OFF for decal to remove more variant + rename

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_DecalsOFF;
         protected ShaderKeyword m_Decals3RT;
         protected ShaderKeyword m_Decals4RT;
 
             m_TileLighting = new ShaderKeyword("USE_FPTL_LIGHTLIST");
             m_ClusterLighting = new ShaderKeyword("USE_CLUSTERED_LIGHTLIST");
             m_LodFadeCrossFade = new ShaderKeyword("LOD_FADE_CROSSFADE");
+            m_DecalsOFF = new ShaderKeyword("DECALS_OFF");
             m_Decals3RT = new ShaderKeyword("DECALS_3RT");
             m_Decals4RT = new ShaderKeyword("DECALS_4RT");
         }
                 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;
+            // If decal support, remove unused variant
+            if (hdrpAsset.renderPipelineSettings.supportDecals)
+            {
+                // Remove the no decal case
+                if (inputData.shaderKeywordSet.IsEnabled(m_DecalsOFF))
+                    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;
+            }
+            else
+            {
+                // If no decal support, remove decal variant
+                if (inputData.shaderKeywordSet.IsEnabled(m_Decals3RT) || inputData.shaderKeywordSet.IsEnabled(m_Decals4RT))
+                    return true;
+            }
+
 
             return false;
         }

com.unity.render-pipelines.high-definition/HDRP/Material/Decal/Decal.hlsl

 #define DBufferType1 float4
 #define DBufferType2 float4
 
-#ifdef _DECALS_4RT
+#ifdef DECALS_4RT
 #define DBufferType3 float2
 
 #define OUTPUT_DBUFFER(NAME)							\
                         , out DBufferType0 outDBuffer0
                         , out DBufferType1 outDBuffer1
                         , out DBufferType2 outDBuffer2
-#ifdef _DECALS_4RT
+#ifdef DECALS_4RT
 						, out DBufferType3 outDBuffer3
 #endif
                         )
     outDBuffer2 = surfaceData.mask;
-#ifdef _DECALS_4RT
+#ifdef DECALS_4RT
 	outDBuffer3 = surfaceData.MAOSBlend;
 #endif
 }
     , DBufferType1 inDBuffer1
     , DBufferType2 inDBuffer2
-#ifdef _DECALS_4RT
+#ifdef DECALS_4RT
 	, DBufferType3 inDBuffer3
 #endif
     , out DecalSurfaceData surfaceData
     surfaceData.normalWS.xyz = inDBuffer1.xyz * 2.0 - 1.0;
     surfaceData.normalWS.w = inDBuffer1.w;
     surfaceData.mask = inDBuffer2;
-#ifdef _DECALS_4RT
+#ifdef DECALS_4RT
 	surfaceData.MAOSBlend = inDBuffer3;
 #else
 	surfaceData.MAOSBlend = float2(surfaceData.mask.w, surfaceData.mask.w);

com.unity.render-pipelines.high-definition/HDRP/Material/Decal/Decal.shader

 	#pragma shader_feature _MASK_BLEND_SRC_B
 
     #pragma multi_compile_instancing
-	#pragma multi_compile _ _DECALS_4RT
+    // No need to teset for DECALS_3RT we are in decal shader, so there is no OFF state
+	#pragma multi_compile _ DECALS_4RT
     //-------------------------------------------------------------------------------------
     // Define
     //-------------------------------------------------------------------------------------

com.unity.render-pipelines.high-definition/HDRP/Material/Decal/DecalUtilities.hlsl

         DBuffer0 = float4(0.0f, 0.0f, 0.0f, 1.0f);
         DBuffer1 = float4(0.5f, 0.5f, 0.5f, 1.0f);
         DBuffer2 = float4(0.0f, 0.0f, 0.0f, 1.0f);
-#ifdef _DECALS_4RT
+#ifdef DECALS_4RT
 		DBuffer3 = float2(1.0f, 1.0f);
 #else
 		float2 DBuffer3 = float2(1.0f, 1.0f);
 
         if (mask & DBUFFERHTILEBIT_MASK)
         {
-#ifdef _DECALS_4RT // only smoothness in 3RT mode
+#ifdef DECALS_4RT // only smoothness in 3RT mode
             surfaceData.metallic = surfaceData.metallic * decalSurfaceData.MAOSBlend.x + decalSurfaceData.mask.x;
 			surfaceData.ambientOcclusion = surfaceData.ambientOcclusion * decalSurfaceData.MAOSBlend.y + decalSurfaceData.mask.y;
 #endif

com.unity.render-pipelines.high-definition/HDRP/Material/LayeredLit/LayeredLit.shader

             #pragma multi_compile _ DIRLIGHTMAP_COMBINED
             #pragma multi_compile _ DYNAMICLIGHTMAP_ON
             #pragma multi_compile _ SHADOWS_SHADOWMASK
-            #pragma multi_compile _ DECALS_3RT DECALS_4RT
+            // Setup DECALS_OFF so the shader stripper can remove variants
+            #pragma multi_compile DECALS_OFF DECALS_3RT DECALS_4RT
 
         #ifdef _ALPHATEST_ON
             // When we have alpha test, we will force a depth prepass so we always bypass the clip instruction in the GBuffer
             #pragma multi_compile _ DIRLIGHTMAP_COMBINED
             #pragma multi_compile _ DYNAMICLIGHTMAP_ON
             #pragma multi_compile _ SHADOWS_SHADOWMASK
-            #pragma multi_compile _ DECALS_3RT DECALS_4RT
+            // Setup DECALS_OFF so the shader stripper can remove variants
+            #pragma multi_compile DECALS_OFF DECALS_3RT DECALS_4RT
 
             // #include "../../Lighting/Forward.hlsl"
             //#pragma multi_compile LIGHTLOOP_SINGLE_PASS LIGHTLOOP_TILE_PASS

com.unity.render-pipelines.high-definition/HDRP/Material/LayeredLit/LayeredLitTessellation.shader

             #pragma multi_compile _ DIRLIGHTMAP_COMBINED
             #pragma multi_compile _ DYNAMICLIGHTMAP_ON
             #pragma multi_compile _ SHADOWS_SHADOWMASK
-            #pragma multi_compile _ DECALS_3RT DECALS_4RT
+            // Setup DECALS_OFF so the shader stripper can remove variants
+            #pragma multi_compile DECALS_OFF DECALS_3RT DECALS_4RT
 
         #ifdef _ALPHATEST_ON
             // When we have alpha test, we will force a depth prepass so we always bypass the clip instruction in the GBuffer
             #pragma multi_compile _ DIRLIGHTMAP_COMBINED
             #pragma multi_compile _ DYNAMICLIGHTMAP_ON
             #pragma multi_compile _ SHADOWS_SHADOWMASK
-            #pragma multi_compile _ DECALS_3RT DECALS_4RT
+            // Setup DECALS_OFF so the shader stripper can remove variants
+            #pragma multi_compile DECALS_OFF DECALS_3RT DECALS_4RT
 
             // #include "../../Lighting/Forward.hlsl"
             //#pragma multi_compile LIGHTLOOP_SINGLE_PASS LIGHTLOOP_TILE_PASS

com.unity.render-pipelines.high-definition/HDRP/Material/Lit/Lit.shader

             #pragma multi_compile _ DIRLIGHTMAP_COMBINED
             #pragma multi_compile _ DYNAMICLIGHTMAP_ON
             #pragma multi_compile _ SHADOWS_SHADOWMASK
-            #pragma multi_compile _ DECALS_3RT DECALS_4RT
+            // Setup DECALS_OFF so the shader stripper can remove variants
+            #pragma multi_compile DECALS_OFF DECALS_3RT DECALS_4RT
 
         #ifdef _ALPHATEST_ON
             // When we have alpha test, we will force a depth prepass so we always bypass the clip instruction in the GBuffer
             #pragma multi_compile _ DIRLIGHTMAP_COMBINED
             #pragma multi_compile _ DYNAMICLIGHTMAP_ON
             #pragma multi_compile _ SHADOWS_SHADOWMASK
-            #pragma multi_compile _ DECALS_3RT DECALS_4RT
+            // Setup DECALS_OFF so the shader stripper can remove variants
+            #pragma multi_compile DECALS_OFF DECALS_3RT DECALS_4RT
 
             // #include "../../Lighting/Forward.hlsl"
             //#pragma multi_compile LIGHTLOOP_SINGLE_PASS LIGHTLOOP_TILE_PASS
             #pragma multi_compile _ DIRLIGHTMAP_COMBINED
             #pragma multi_compile _ DYNAMICLIGHTMAP_ON
             #pragma multi_compile _ SHADOWS_SHADOWMASK
-            #pragma multi_compile _ DECALS_3RT DECALS_4RT
+            // Setup DECALS_OFF so the shader stripper can remove variants
+            #pragma multi_compile DECALS_OFF DECALS_3RT DECALS_4RT
 
             // #include "../../Lighting/Forward.hlsl"
             //#pragma multi_compile LIGHTLOOP_SINGLE_PASS LIGHTLOOP_TILE_PASS

com.unity.render-pipelines.high-definition/HDRP/Material/Lit/LitTessellation.shader

             #pragma multi_compile _ DIRLIGHTMAP_COMBINED
             #pragma multi_compile _ DYNAMICLIGHTMAP_ON
             #pragma multi_compile _ SHADOWS_SHADOWMASK
-            #pragma multi_compile _ DECALS_3RT DECALS_4RT
+            // Setup DECALS_OFF so the shader stripper can remove variants
+            #pragma multi_compile DECALS_OFF DECALS_3RT DECALS_4RT
 
         #ifdef _ALPHATEST_ON
             // When we have alpha test, we will force a depth prepass so we always bypass the clip instruction in the GBuffer
             #pragma multi_compile _ DIRLIGHTMAP_COMBINED
             #pragma multi_compile _ DYNAMICLIGHTMAP_ON
             #pragma multi_compile _ SHADOWS_SHADOWMASK
-            #pragma multi_compile _ DECALS_3RT DECALS_4RT
+            // Setup DECALS_OFF so the shader stripper can remove variants
+            #pragma multi_compile DECALS_OFF DECALS_3RT DECALS_4RT
 
             // #include "../../Lighting/Forward.hlsl"
             //#pragma multi_compile LIGHTLOOP_SINGLE_PASS LIGHTLOOP_TILE_PASS
             #pragma multi_compile _ DIRLIGHTMAP_COMBINED
             #pragma multi_compile _ DYNAMICLIGHTMAP_ON
             #pragma multi_compile _ SHADOWS_SHADOWMASK
-            #pragma multi_compile _ DECALS_3RT DECALS_4RT
+            // Setup DECALS_OFF so the shader stripper can remove variants
+            #pragma multi_compile DECALS_OFF DECALS_3RT DECALS_4RT
 
             // #include "../../Lighting/Forward.hlsl"
             //#pragma multi_compile LIGHTLOOP_SINGLE_PASS LIGHTLOOP_TILE_PASS

com.unity.render-pipelines.high-definition/HDRP/Material/StackLit/StackLit.shader

             #pragma multi_compile _ DIRLIGHTMAP_COMBINED
             #pragma multi_compile _ DYNAMICLIGHTMAP_ON
             #pragma multi_compile _ SHADOWS_SHADOWMASK
-            #pragma multi_compile _ DECALS_3RT DECALS_4RT
+            // Setup DECALS_OFF so the shader stripper can remove variants
+            #pragma multi_compile DECALS_OFF DECALS_3RT DECALS_4RT
 
             // #include "../../Lighting/Forward.hlsl" : nothing left in there.
             //#pragma multi_compile LIGHTLOOP_SINGLE_PASS LIGHTLOOP_TILE_PASS

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

         {
             if (m_Asset.renderPipelineSettings.supportDecals)
             {
+                CoreUtils.SetKeyword(cmd, "DECALS_OFF", false);
+                CoreUtils.SetKeyword(cmd, "DECALS_OFF", true);
                 CoreUtils.SetKeyword(cmd, "DECALS_3RT", false);
                 CoreUtils.SetKeyword(cmd, "DECALS_4RT", false);
             }