Move orthonormalization into GetSurfaceAndBuiltinData()

Assets/ScriptableRenderLoop/HDRenderPipeline/Lighting/Resources/Deferred.shader

                 float3 bakeDiffuseLighting;
                 DECODE_FROM_GBUFFER(gbuffer, bsdfData, bakeDiffuseLighting);
 
-                bool twoSided = false;
-                float NdotV = GetShiftedNdotV(bsdfData.normalWS, V, twoSided);
-
-                PreLightData preLightData = GetPreLightData(V, NdotV, posInput, bsdfData);
+                PreLightData preLightData = GetPreLightData(V, posInput, bsdfData);
 
                 float3 diffuseLighting;
                 float3 specularLighting;

Assets/ScriptableRenderLoop/HDRenderPipeline/Lighting/TilePass/Resources/shadeopaque.compute

     float3 bakeDiffuseLighting;
     DECODE_FROM_GBUFFER(gbuffer, bsdfData, bakeDiffuseLighting);
 
-    bool twoSided = false;
-    float NdotV = GetShiftedNdotV(bsdfData.normalWS, V, twoSided);
-
-    PreLightData preLightData = GetPreLightData(V, NdotV, posInput, bsdfData);
+    PreLightData preLightData = GetPreLightData(V, posInput, bsdfData);
 
     float3 diffuseLighting;
     float3 specularLighting;

Assets/ScriptableRenderLoop/HDRenderPipeline/Material/Lit/Lit.hlsl

     float    ltcDisneyDiffuseMagnitude;
 };
 
-PreLightData GetPreLightData(float3 V, float NdotV, PositionInputs posInput, BSDFData bsdfData)
+PreLightData GetPreLightData(float3 V, PositionInputs posInput, BSDFData bsdfData)
-    preLightData.NdotV = NdotV;
+    // We do not saturate to correctly handle double-sided lighting.
+    preLightData.NdotV = dot(bsdfData.normalWS, V);
 
     preLightData.ggxLambdaV = GetSmithJointGGXLambdaV(preLightData.NdotV, bsdfData.roughness);
 
 
     // Area light specific
     // UVs for sampling the LUTs
-    float theta = FastACos(dot(bsdfData.normalWS, V));
+    float theta = FastACos(preLightData.NdotV);
     // Scale and bias for the current precomputed table - the constant use here are the one that have been use when the table in LtcData.DisneyDiffuse.cs and LtcData.GGX.cs was use
     float2 uv = 0.0078125 + 0.984375 * float2(bsdfData.perceptualRoughness, theta * INV_HALF_PI);
 

Assets/ScriptableRenderLoop/HDRenderPipeline/Material/Lit/LitData.hlsl

     float3 normalTS;
     float alpha = GetSurfaceData(input, layerTexCoord, surfaceData, normalTS);
     surfaceData.normalWS = TransformTangentToWorld(normalTS, input.tangentToWorld);
+    surfaceData.tangentWS = input.tangentToWorld[0].xyz;
+
+    bool twoSided = false;
+    // This will always produce the correct 'NdotV' value, but potentially
+    // reduce the length of the normal at edges of geometry.
+    GetShiftedNdotV(surfaceData.normalWS, V, twoSided);
+
+    // Orthonormalize the basis vectors using the Gram-Schmidt process.
+    // We assume that the length of the surface normal is sufficiently close to 1.
+    surfaceData.tangentWS = normalize(surfaceData.tangentWS - dot(surfaceData.tangentWS, surfaceData.normalWS));
+
     // Caution: surfaceData must be fully initialize before calling GetBuiltinData
     GetBuiltinData(input, surfaceData, alpha, depthOffset, builtinData);
 }
     normalTS = BlendLayeredFloat3(normalTS0, normalTS1, normalTS2, normalTS3, weights);
 #endif
     surfaceData.normalWS = TransformTangentToWorld(normalTS, input.tangentToWorld);
+    surfaceData.tangentWS = input.tangentToWorld[0].xyz;
+
+    bool twoSided = false;
+    // This will  potentially reduce the length of the normal at edges of geometry.
+    GetShiftedNdotV(surfaceData.normalWS, V, twoSided);
+
+    // Orthonormalize the basis vectors using the Gram-Schmidt process.
+    // We assume that the length of the surface normal is sufficiently close to 1.
+    surfaceData.tangentWS = normalize(surfaceData.tangentWS - dot(surfaceData.tangentWS, surfaceData.normalWS));
-    surfaceData.tangentWS = input.tangentToWorld[0].xyz;
     surfaceData.anisotropy = 0;
     surfaceData.specular = 0.04;
     surfaceData.subSurfaceRadius = 1.0;

Assets/ScriptableRenderLoop/HDRenderPipeline/ShaderPass/ShaderPassForward.hlsl

     BuiltinData builtinData;
     GetSurfaceAndBuiltinData(input, V, posInput, surfaceData, builtinData);
 
-    bool twoSided = false;
-    // This will always produce the correct 'NdotV' value, but potentially
-    // reduce the length of the normal at edges of geometry.
-    float NdotV = GetShiftedNdotV(surfaceData.normalWS, V, twoSided);
-
-    // Orthonormalize the basis vectors using the Gram-Schmidt process.
-    surfaceData.normalWS  = normalize(surfaceData.normalWS);
-    surfaceData.tangentWS = normalize(surfaceData.tangentWS - dot(surfaceData.tangentWS, surfaceData.normalWS));
-
-	PreLightData preLightData = GetPreLightData(V, NdotV, posInput, bsdfData);
+	PreLightData preLightData = GetPreLightData(V, posInput, bsdfData);
 
 	float3 diffuseLighting;
 	float3 specularLighting;

Assets/ScriptableRenderLoop/HDRenderPipeline/ShaderPass/ShaderPassGBuffer.hlsl

 	BuiltinData builtinData;
 	GetSurfaceAndBuiltinData(input, V, posInput, surfaceData, builtinData);
 
-    bool twoSided = false;
-    // This will always produce the correct 'NdotV' value, but potentially
-    // reduce the length of the normal at edges of geometry.
-    float NdotV = GetShiftedNdotV(surfaceData.normalWS, V, twoSided);
-
-    // Orthonormalize the basis vectors using the Gram-Schmidt process.
-    surfaceData.normalWS  = normalize(surfaceData.normalWS);
-    surfaceData.tangentWS = normalize(surfaceData.tangentWS - dot(surfaceData.tangentWS, surfaceData.normalWS));
-
-	PreLightData preLightData = GetPreLightData(V, NdotV, posInput, bsdfData);
+	PreLightData preLightData = GetPreLightData(V, posInput, bsdfData);
 
     float3 bakeDiffuseLighting = GetBakedDiffuseLigthing(surfaceData, builtinData, bsdfData, preLightData);
 

Assets/ScriptableRenderLoop/HDRenderPipeline/ShaderVariables.hlsl

 // Computes world space view direction, from object space position
 float3 GetWorldSpaceNormalizeViewDir(float3 positionWS)
 {
-    return normalize(_WorldSpaceCameraPos.xyz - positionWS);
+    float3 V = _WorldSpaceCameraPos.xyz - positionWS;
+
+    // Uncomment this once the compiler bug is fixed.
+    // if (unity_OrthoParams.w == 1.0)
+    // {
+    //     float4x4 M = GetWorldToViewMatrix();
+    //     V = M[1].xyz;
+    // }
+
+    return normalize(V);
 }
 
 float3 TransformTangentToWorld(float3 dirTS, float3 tangentToWorld[3])

Assets/ScriptableRenderLoop/ShaderLibrary/CommonLighting.hlsl

 float GetShiftedNdotV(inout float3 N, float3 V, bool twoSided)
 {
     float NdotV = dot(N, V);
-    float limit = 1e-4;
+    float limit = rcp(256.0); // Determined mostly by the quality of the G-buffer normal encoding
 
     if (!twoSided && NdotV < limit)
     {