虚幻4 Gbuffer

// all values that are output by the forward rendering pass
struct FGBufferData
{
    // normalized
    float3 WorldNormal;
    // 0..1 (derived from BaseColor, Metalness, Specular)
    float3 DiffuseColor;
    // 0..1 (derived from BaseColor, Metalness, Specular)
    float3 SpecularColor;
    // 0..1, white for SHADINGMODELID_SUBSURFACE_PROFILE and SHADINGMODELID_EYE (apply BaseColor after scattering is more correct and less blurry)
    float3 BaseColor;
    // 0..1
    float Metallic;
    // 0..1
    float Specular;
    // 0..1
    float4 CustomData;
    // Indirect irradiance luma
    float IndirectIrradiance;
    // Static shadow factors for channels assigned by Lightmass
    // Lights using static shadowing will pick up the appropriate channel in their deferred pass
    float4 PrecomputedShadowFactors;
    // 0..1
    float Roughness;
    // 0..1 ambient occlusion  e.g.SSAO, wet surface mask, skylight mask, ...
    float GBufferAO;
    // 0..255 
    uint ShadingModelID;
    // 0..255 
    uint SelectiveOutputMask;
    // 0..1, 2 bits, use HasDistanceFieldRepresentation(GBuffer) or HasDynamicIndirectShadowCasterRepresentation(GBuffer) to extract
    float PerObjectGBufferData;
    // in world units
    float CustomDepth;
    // Custom depth stencil value
    uint CustomStencil;
    // in unreal units (linear), can be used to reconstruct world position,
    // only valid when decoding the GBuffer as the value gets reconstructed from the Z buffer
    float Depth;
    // Velocity for motion blur (only used when WRITES_VELOCITY_TO_GBUFFER is enabled)
    float4 Velocity;

    // 0..1, only needed by SHADINGMODELID_SUBSURFACE_PROFILE and SHADINGMODELID_EYE which apply BaseColor later
    float3 StoredBaseColor;
    // 0..1, only needed by SHADINGMODELID_SUBSURFACE_PROFILE and SHADINGMODELID_EYE which apply Specular later
    float StoredSpecular;
    // 0..1, only needed by SHADINGMODELID_EYE which encodes Iris Distance inside Metallic
    float StoredMetallic;
};

位置在（UE_4.21\Engine\Shaders\Private\DeferredShadingCommon.ush）  

这个Gbuffer有点大啊