some transparency

res/shaders/lib/BRDF.slang

@@ -5,6 +5,7 @@ interface IBRDF
     float3 evaluate(float3 viewDir_TS, float3 lightDir_TS, float3 lightColor);
     float3 evaluateAmbient();
     float getAlpha();
+    float3 getTangentNormal();
 };
 
 struct Phong : IBRDF
@@ -40,6 +41,10 @@ struct Phong : IBRDF
     {
         return alpha;
     }
+    float3 getTangentNormal()
+    {
+        return normal;
+    }
 };
 
 struct BlinnPhong : IBRDF
@@ -75,6 +80,10 @@ struct BlinnPhong : IBRDF
     {
         return alpha;
     }
+    float3 getTangentNormal()
+    {
+        return normal;
+    }
 };
 
 struct CelShading : IBRDF
@@ -113,6 +122,10 @@ struct CelShading : IBRDF
     {
         return alpha;
     }
+    float3 getTangentNormal()
+    {
+        return normal;
+    }
 };
 
 // https://learnopengl.com/PBR/Theory
@@ -201,4 +214,8 @@ struct CookTorrance : IBRDF
     {
         return alpha;
     }
+    float3 getTangentNormal()
+    {
+        return normal;
+    }
 };

res/shaders/lib/MaterialParameter.slang

@@ -49,6 +49,11 @@ struct FragmentParameter
         result.normal_TS = mul(tbn, normal_WS);
 		return result;
 	}
+    float3x3 getTangentToWorld()
+    {
+        float3x3 tbn = float3x3(normalize(tangent_WS), normalize(biTangent_WS), normalize(normal_WS));
+		return transpose(tbn);
+    }
 #endif
     static FragmentParameter interpolate(FragmentParameter f0, FragmentParameter f1, FragmentParameter f2, float3 barycentricCoords)
     {