generating decal normal to decal space matrix in vertex shader

ScriptableRenderPipeline/HDRenderPipeline/HDRP/Material/Decal/DecalData.hlsl

 #include "CoreRP/ShaderLibrary/Packing.hlsl"
 #include "CoreRP/ShaderLibrary/Sampling/SampleUVMapping.hlsl"
 
-void GetSurfaceData(float2 texCoordDS, out DecalSurfaceData surfaceData)
+void GetSurfaceData(float2 texCoordDS, float3x3 decalToWorld, out DecalSurfaceData surfaceData)
 {
 	surfaceData.baseColor = float4(0,0,0,0);
 	surfaceData.normalWS = float4(0,0,0,0);
 	ZERO_INITIALIZE(UVMapping, texCoord);
 	texCoord.uv = texCoordDS.xy;
 #if _NORMALMAP
-	surfaceData.normalWS.xyz = mul((float3x3)_DecalToWorldR, SAMPLE_UVMAPPING_NORMALMAP(_NormalMap, sampler_NormalMap, texCoord, 1)) * 0.5f + 0.5f;
+//	surfaceData.normalWS.xyz = mul((float3x3)_DecalToWorldR, SAMPLE_UVMAPPING_NORMALMAP(_NormalMap, sampler_NormalMap, texCoord, 1)) * 0.5f + 0.5f;
+	surfaceData.normalWS.xyz = mul(decalToWorld, SAMPLE_UVMAPPING_NORMALMAP(_NormalMap, sampler_NormalMap, texCoord, 1)) * 0.5f + 0.5f;
 	surfaceData.normalWS.w = totalBlend;
 #endif
 #if _MASKMAP

ScriptableRenderPipeline/HDRenderPipeline/HDRP/Material/Decal/ShaderPass/DecalSharePass.hlsl

 #error Undefine_SHADERPASS
 #endif
 
+// 3 interpolators for decal normal map tangent space
+#define VARYINGS_NEED_POSITION_WS
+#define VARYINGS_NEED_TANGENT_TO_WORLD
 
 // This include will define the various Attributes/Varyings structure
 #include "../../ShaderPass/VaryingMesh.hlsl"

ScriptableRenderPipeline/HDRenderPipeline/HDRP/ShaderPass/ShaderPassDBuffer.hlsl

 
 #include "VertMesh.hlsl"
 
+float3 RemoveScale(float3 val)
+{
+	return normalize(val / length(val));
+}
+
+VaryingsMeshType Transform(AttributesMesh input)
+{
+    VaryingsMeshType output;
+
+    float3 positionWS = TransformObjectToWorld(input.positionOS);
+	positionWS = GetCameraRelativePositionWS(positionWS);
+	output.positionCS = TransformWorldToHClip(positionWS);
+
+	float3x3 decalRotation;
+	decalRotation[0] = RemoveScale(float3(UNITY_MATRIX_M[0][0], UNITY_MATRIX_M[0][1], UNITY_MATRIX_M[0][2]));
+	decalRotation[2] = RemoveScale(float3(UNITY_MATRIX_M[1][0], UNITY_MATRIX_M[1][1], UNITY_MATRIX_M[1][2]));
+	decalRotation[1] = RemoveScale(float3(UNITY_MATRIX_M[2][0], UNITY_MATRIX_M[2][1], UNITY_MATRIX_M[2][2]));
+
+	decalRotation = transpose(decalRotation);
+
+	output.positionWS = decalRotation[0];
+    output.normalWS = decalRotation[1];
+    output.tangentWS = float4(decalRotation[2], 0);
+
+    return output;
+}
+
-    varyingsType.vmesh = VertMesh(inputMesh);
+    varyingsType.vmesh = Transform(inputMesh);
     return PackVaryingsType(varyingsType);
 }
 
 	clip(positionDS > 1 ? -1 : 1);
 
     DecalSurfaceData surfaceData;
-    GetSurfaceData(positionDS.xz, surfaceData);
+	float3x3 decalToWorld;
+	decalToWorld[0] = packedInput.vmesh.interpolators0;
+	decalToWorld[1] = packedInput.vmesh.interpolators1;
+	decalToWorld[2] = packedInput.vmesh.interpolators2.xyz;
+
+    GetSurfaceData(positionDS.xz, decalToWorld, surfaceData);
 
 	ENCODE_INTO_DBUFFER(surfaceData, outDBuffer);
 }

ScriptableRenderPipeline/HDRenderPipeline/HDRP/ShaderPass/VertMesh.hlsl

     float3 normalWS = float3(0.0, 0.0, 0.0); // We need this case to be able to compile ApplyVertexModification that doesn't use normal.
 #endif
 
+	float4 tangentWS = float4(0.0, 0.0, 0.0, 0.0);
-    float4 tangentWS = float4(TransformObjectToWorldDir(input.tangentOS.xyz), input.tangentOS.w);
+    tangentWS = float4(TransformObjectToWorldDir(input.tangentOS.xyz), input.tangentOS.w);
 #endif
 
     // TODO: deal with camera center rendering and instancing (This is the reason why we always perform two  steps transform to clip space + instancing matrix)