Adding support for the tangent map

Correcting review problems

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

             // public static GUIContent bentNormalMapText = new GUIContent("Bent normal map", "Use only with indirect diffuse lighting (Lightmap/light-probe) - Cosine weighted Bent Normal Map (average un-occluded direction) (BC7/BC5/DXT5(nm))");
 
             // Tangent map
-            // public static GUIContent tangentMapText = new GUIContent("Tangent Map", "Tangent Map (BC7/BC5/DXT5(nm))");
+            public static GUIContent tangentMapText = new GUIContent("Tangent Map", "Tangent Map (BC7/BC5/DXT5(nm))");
            
             // Anisotropy
             public static GUIContent anisotropyText = new GUIContent("Anisotropy", "Anisotropy scale factor");
         protected const string kNormalMap = "_NormalMap";
         // protected MaterialProperty bentNormalMap = null;
         // protected const string kBentNormalMap = "_BentNormalMap";
+
+        // Tangent Map
+        protected MaterialProperty tangentMap = null;
+        protected const string kTangentMap = "_TangentMap";
 
         // Fuzz Tint
         protected MaterialProperty fuzzTint = null;
             normalMap = FindProperty(kNormalMap, props);
             normalScale = FindProperty(kNormalScale, props);
             // bentNormalMap = FindProperty(kBentNormalMap, props);
+
+            // Tangent map
+            tangentMap = FindProperty(kTangentMap, props);
 
             // Fuzz tint
             fuzzTint = FindProperty(kFuzzTint, props);
             FabricType fabricType = (FabricType)material.GetFloat(kFabricType);
             if(fabricType == FabricType.Silk)
             {
-                //m_MaterialEditor.TexturePropertySingleLine(Styles.tangentMapText, tangentMap);
+                m_MaterialEditor.TexturePropertySingleLine(Styles.tangentMapText, tangentMap);
                 m_MaterialEditor.ShaderProperty(anisotropy, Styles.anisotropyText);
                 m_MaterialEditor.TexturePropertySingleLine(Styles.anisotropyMapText, anisotropyMap);
             }

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

         _NormalMap("NormalMap", 2D) = "bump" {}     // Tangent space normal map
         _NormalScale("_NormalScale", Range(0.0, 2.0)) = 1
 
-        // TODO
-        // _TangentMap("TangentMap", 2D) = "bump" {}
+        // Tangent map
+        _TangentMap("TangentMap", 2D) = "bump" {}
 
         // Smoothness values (overriden by the mask map)
         _Smoothness("Smoothness", Range(0.0, 1.0)) = 1.0

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

 
 void GetSurfaceAndBuiltinData(FragInputs input, float3 V, inout PositionInputs posInput, out SurfaceData surfaceData, out BuiltinData builtinData)
 {
-    // TODO: Remove this zero initialize once we have written all the code
-    ZERO_INITIALIZE(SurfaceData, surfaceData);
-
+    // Initial value of the material features
+    surfaceData.materialFeatures = 0;
+    
-    surfaceData.materialFeatures = MATERIALFEATUREFLAGS_FABRIC_COTTON_WOOL;
+    surfaceData.materialFeatures |= MATERIALFEATUREFLAGS_FABRIC_COTTON_WOOL;
 #endif
 
 #ifdef _MATERIAL_FEATURE_SUBSURFACE_SCATTERING
 
 #ifdef _NORMALMAP
     float2 derivative = UnpackDerivativeNormalRGorAG(SAMPLE_TEXTURE2D(_NormalMap, sampler_NormalMap, uvBase), _NormalScale);
-    float3 gradient =  SurfaceGradientFromTBN(derivative, input.worldToTangent[0], input.worldToTangent[1]) + detailGradient * detailMasks.x;
+    #ifdef _DETAIL_MAP
+        float3 gradient =  SurfaceGradientFromTBN(derivative, input.worldToTangent[0], input.worldToTangent[1]) + detailGradient * detailMasks.x;
+    #else
+        float3 gradient =  SurfaceGradientFromTBN(derivative, input.worldToTangent[0], input.worldToTangent[1]);
+    #endif
+#ifdef _TANGENTMAP
+    float3 tangentTS = UnpackNormalmapRGorAG(SAMPLE_TEXTURE2D(_TangentMap, sampler_TangentMap, uvBase, 1.0));
+    surfaceData.tangentWS = TransformTangentToWorld(tangentTS, input.worldToTangent);
+#else
+    surfaceData.tangentWS = normalize(input.worldToTangent[0].xyz); // The tangent is not normalize in worldToTangent for mikkt. TODO: Check if it expected that we normalize with Morten. Tag: SURFACE_GRADIENT
+#endif
+
     // Make the tagent match the normal
     surfaceData.tangentWS = Orthonormalize(input.worldToTangent[0], surfaceData.normalWS);
 
     surfaceData.perceptualSmoothness = lerp(surfaceData.perceptualSmoothness, saturate(smoothnessOverlay), detailMask.x);
 #endif
     
+// If a detail map was provided, modify the matching ao
+#ifdef _DETAIL_MAP
+    float aoDetailSpeed = saturate(abs(detailAO) * _DetailAOScale);
+    float aoOverlay = lerp(surfaceData.ambientOcclusion, (aoDetailSpeed < 0.0) ? 0.0 : 1.0, aoDetailSpeed);
+    surfaceData.ambientOcclusion = lerp(surfaceData.ambientOcclusion, saturate(aoOverlay), detailMask.x);
+#endif
+    
+
     // Propagate the fuzz tint
     surfaceData.fuzzTint = _FuzzTint.xyz;
 
     #else
         surfaceData.subsurfaceMask = _SubsurfaceMask;
     #endif
+#else
+    surfaceData.subsurfaceMask = 0.0;
+    surfaceData.diffusionProfile = 0;
 #endif
 
 #ifdef _MATERIALFEATUREFLAGS_FABRIC_TRANSMISSION

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

 
 TEXTURE2D(_TangentMap);
 SAMPLER(sampler_TangentMap);
-TEXTURE2D(_TangentMapOS);
-SAMPLER(sampler_TangentMapOS);
 
 TEXTURE2D(_AnisotropyMap);
 SAMPLER(sampler_AnisotropyMap);