void BuildInputData(Varyings input, SurfaceDescription surfaceDescription, out InputData inputData)
{
    inputData.positionWS = input.positionWS;
    #ifdef _NORMALMAP

        #if _NORMAL_DROPOFF_TS
            // IMPORTANT! If we ever support Flip on double sided materials ensure bitangent and tangent are NOT flipped.
            float crossSign = (input.tangentWS.w > 0.0 ? 1.0 : -1.0) * GetOddNegativeScale();
            float3 bitangent = crossSign * cross(input.normalWS.xyz, input.tangentWS.xyz);
            inputData.normalWS = TransformTangentToWorld(surfaceDescription.NormalTS, half3x3(input.tangentWS.xyz, bitangent, input.normalWS.xyz));
        #elif _NORMAL_DROPOFF_OS
            inputData.normalWS = TransformObjectToWorldNormal(surfaceDescription.NormalOS);
        #elif _NORMAL_DROPOFF_WS
            inputData.normalWS = surfaceDescription.NormalWS;
        #endif
    #else
        inputData.normalWS = input.normalWS;
    #endif
    inputData.normalWS = NormalizeNormalPerPixel(inputData.normalWS);
    inputData.viewDirectionWS = SafeNormalize(input.viewDirectionWS);

#if defined(MAIN_LIGHT_CALCULATE_SHADOWS)
    inputData.shadowCoord = TransformWorldToShadowCoord(inputData.positionWS);
#else
    inputData.shadowCoord = float4(0, 0, 0, 0);
#endif

    inputData.fogCoord = input.fogFactorAndVertexLight.x;
    inputData.vertexLighting = input.fogFactorAndVertexLight.yzw;
    inputData.bakedGI = SAMPLE_GI(input.lightmapUV, input.sh, inputData.normalWS);
    inputData.normalizedScreenSpaceUV = GetNormalizedScreenSpaceUV(input.positionCS);
    inputData.shadowMask = SAMPLE_SHADOWMASK(input.lightmapUV);
}

PackedVaryings vert(Attributes input)
{
    Varyings output = (Varyings)0;
    output = BuildVaryings(input);
    PackedVaryings packedOutput = (PackedVaryings)0;
    packedOutput = PackVaryings(output);
    return packedOutput;
}

FragmentOutput frag(PackedVaryings packedInput)
{
    Varyings unpacked = UnpackVaryings(packedInput);
    UNITY_SETUP_INSTANCE_ID(unpacked);
    UNITY_SETUP_STEREO_EYE_INDEX_POST_VERTEX(unpacked);

    SurfaceDescriptionInputs surfaceDescriptionInputs = BuildSurfaceDescriptionInputs(unpacked);
    SurfaceDescription surfaceDescription = SurfaceDescriptionFunction(surfaceDescriptionInputs);

    #if _AlphaClip
        half alpha = surfaceDescription.Alpha;
        clip(alpha - surfaceDescription.AlphaClipThreshold);
    #elif _SURFACE_TYPE_TRANSPARENT
        half alpha = surfaceDescription.Alpha;
    #else
        half alpha = 1;
    #endif

    InputData inputData;
    BuildInputData(unpacked, surfaceDescription, inputData);

    #ifdef _SPECULAR_SETUP
        float3 specular = surfaceDescription.Specular;
        float metallic = 1;
    #else
        float3 specular = 0;
        float metallic = surfaceDescription.Metallic;
    #endif

    // in LitForwardPass GlobalIllumination (and temporarily LightingPhysicallyBased) are called inside UniversalFragmentPBR
    // in Deferred rendering we store the sum of these values (and of emission as well) in the GBuffer
    BRDFData brdfData;
    InitializeBRDFData(surfaceDescription.BaseColor, metallic, specular, surfaceDescription.Smoothness, alpha, brdfData);

    Light mainLight = GetMainLight(inputData.shadowCoord, inputData.positionWS, inputData.shadowMask);
    MixRealtimeAndBakedGI(mainLight, inputData.normalWS, inputData.bakedGI, inputData.shadowMask);
    half3 color = GlobalIllumination(brdfData, inputData.bakedGI, surfaceDescription.Occlusion, inputData.normalWS, inputData.viewDirectionWS);

    return BRDFDataToGbuffer(brdfData, inputData, surfaceDescription.Smoothness, surfaceDescription.Emission + color);
}