SubsurfaceProfile.h

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// Copyright Epic Games, Inc. All Rights Reserved.
#pragma once
 
#include "CoreMinimal.h"
#include "UObject/ObjectMacros.h"
#include "UObject/Object.h"
#include "RenderResource.h"
#include "SubsurfaceProfile.generated.h"
 
#define MAX_SUBSURFACE_PROFILE_COUNT 256
 
UENUM()
enum class ESubsurfaceImplementationTechniqueHint : uint8
{
    SIH_AFIS UMETA(DisplayName = "Adaptive Filtered Importance Sampling"),
 
    SIH_Separable UMETA(DisplayName = "Separable"),
};
 
// struct with all the settings we want in USubsurfaceProfile, separate to make it easer to pass this data around in the engine.
USTRUCT(BlueprintType)
struct FSubsurfaceProfileStruct
{
    GENERATED_USTRUCT_BODY()
    
    
    UPROPERTY(Category = "Burley Normalized", EditAnywhere, BlueprintReadOnly, meta = (ClampMin = "0.01", UIMax = "1.0", ClampMax = "1.0", HideAlphaChannel, editcondition = "bEnableBurley"))
    FLinearColor SurfaceAlbedo;
 
    UPROPERTY(Category = "Burley Normalized", EditAnywhere, BlueprintReadOnly, meta = (ClampMin = "0.001", UIMax = "1.0", ClampMax = "1.0", HideAlphaChannel, editcondition = "bEnableBurley"))
    FLinearColor MeanFreePathColor; //MeanFreePathLength;
    
    UPROPERTY(Category = "Burley Normalized", EditAnywhere, BluePrintReadOnly, meta = (ClampMin = "0.1", UIMax = "50.0", ClampMax = "50.0", editcondition = "bEnableBurley"))
    float MeanFreePathDistance;
 
    UPROPERTY(Category = "Burley Normalized", EditAnywhere, BlueprintReadOnly, meta = (ClampMin = "0.1", UIMax = "50.0", ClampMax = "50.0", editcondition = "bEnableBurley"))
    float WorldUnitScale;
 
    UPROPERTY(Category = "Burley Normalized", EditAnywhere, BlueprintReadOnly, meta = (editcondition = "false", EditConditionHides))
    bool  bEnableBurley;
 
    UPROPERTY(Category = "Burley Normalized", EditAnywhere, BlueprintReadOnly, meta = (editcondition = "false", EditConditionHides))
    bool  bEnableMeanFreePath;
 
    UPROPERTY(Category = "Burley Normalized", EditAnywhere, BlueprintReadOnly, meta = (HideAlphaChannel, editcondition = "bEnableBurley"))
    FLinearColor Tint;
 
    UPROPERTY(Category = "SubsurfaceProfileStruct", EditAnywhere, BlueprintReadOnly, meta = (ClampMin = "0.1", UIMax = "50.0", ClampMax = "1000.0", DeprecatedProperty, editcondition = "!bEnableBurley", EditConditionHides))
    float ScatterRadius;
 
    UPROPERTY(Category = "SubsurfaceProfileStruct", EditAnywhere, BlueprintReadOnly, meta = (HideAlphaChannel, DeprecatedProperty, editcondition = "!bEnableBurley", EditConditionHides))
    FLinearColor SubsurfaceColor;
 
    UPROPERTY(Category = "SubsurfaceProfileStruct", EditAnywhere, BlueprintReadOnly, meta = (HideAlphaChannel, DeprecatedProperty, editcondition = "!bEnableBurley", EditConditionHides))
    FLinearColor FalloffColor;
 
    UPROPERTY(Category = "Burley Normalized", EditAnywhere, BlueprintReadOnly, meta = (HideAlphaChannel))
    FLinearColor BoundaryColorBleed;
 
    UPROPERTY(Category = "Burley Normalized", EditAnywhere, BlueprintReadOnly)
    ESubsurfaceImplementationTechniqueHint Implementation;
 
    UPROPERTY(Category = "Transmission", EditAnywhere, BlueprintReadOnly, meta = (ClampMin = "0.01", UIMax = "100.0", ClampMax = "100.0", SliderExponent="24"))
    float ExtinctionScale;
    
    UPROPERTY(Category = "Transmission", EditAnywhere, BlueprintReadOnly, meta = (ClampMin = "0.01", UIMax = "0.99", ClampMax = "1.0"))
    float NormalScale;
 
    UPROPERTY(Category = "Transmission", EditAnywhere, BlueprintReadOnly, meta = (ClampMin = "0.01", UIMax = "0.99", ClampMax = "1.0"))
    float ScatteringDistribution;
 
    UPROPERTY(Category = "Transmission", EditAnywhere, BlueprintReadOnly, meta = (ClampMin = "1.0", UIMax = "3.0", ClampMax = "3.0"))
    float IOR;
 
    UPROPERTY(Category = "Dual Specular", EditAnywhere, BlueprintReadOnly, meta = (ClampMin = "0.5", UIMax = "2.0", ClampMax = "2.0"))
    float Roughness0;
 
    UPROPERTY(Category = "Dual Specular", EditAnywhere, BlueprintReadOnly, meta = (ClampMin = "0.5", UIMax = "2.0", ClampMax = "2.0"))
    float Roughness1;
 
    UPROPERTY(Category = "Dual Specular", EditAnywhere, BlueprintReadOnly, meta = (ClampMin = "0.1", UIMax = "0.9", ClampMax = "0.9"))
    float LobeMix;
 
    UPROPERTY(Category = "Transmission", EditAnywhere, BlueprintReadOnly, meta = (ClampMin = "0.001", UIMax = "1.0", ClampMax = "1.0", HideAlphaChannel))
    FLinearColor TransmissionTintColor;
 
    // constructor
    FSubsurfaceProfileStruct()
    {
        // defaults from SeparableSSS.h and the demo
        ScatterRadius = 1.2f;
        SubsurfaceColor = FLinearColor(0.48f, 0.41f, 0.28f);
        FalloffColor = FLinearColor(1.0f, 0.37f, 0.3f);
        BoundaryColorBleed = FLinearColor::White;
        ExtinctionScale = 1.0f;
        ScatteringDistribution = 0.93f;
        NormalScale = 0.08f;
        IOR = 1.55f;
        Roughness0 = 0.75f;
        Roughness1 = 1.30f;
        LobeMix = 0.85f;
        bEnableBurley = false;
        //match FalloffColor exactly for the default setting
        SurfaceAlbedo = FLinearColor(0.91058f,0.338275f,0.2718f);
        MeanFreePathColor = FLinearColor(1.0f,0.1983f/2.229f,0.1607f/2.229f);
        MeanFreePathDistance = 1.2f*2.229f;
        WorldUnitScale = 0.1f;
        TransmissionTintColor = FLinearColor(1.0f, 1.0f, 1.0f);
        Tint = FLinearColor(1.0f, 1.0f, 1.0f);
        Implementation = ESubsurfaceImplementationTechniqueHint::SIH_AFIS;
        bEnableMeanFreePath = false;
    }
 
    void Invalidate()
    {
        *this = FSubsurfaceProfileStruct();
    }
};
 
UCLASS(autoexpandcategories = SubsurfaceProfile, MinimalAPI)
class USubsurfaceProfile : public UObject
{
    GENERATED_UCLASS_BODY()
 
    UPROPERTY(Category = USubsurfaceProfile, EditAnywhere, meta = (ShowOnlyInnerProperties))
    struct FSubsurfaceProfileStruct Settings;
 
    UPROPERTY()
    FGuid Guid;
 
    //~ Begin UObject Interface
    virtual void BeginDestroy();
    virtual void PostEditChangeProperty(struct FPropertyChangedEvent& PropertyChangedEvent);
    virtual void PostDuplicate(EDuplicateMode::Type DuplicateMode);
    virtual void Serialize(FArchive& Ar) override;
 
    // Upgrade parameters from Separable to Burley.
    virtual void PostLoad();
    //~ End UObject Interface
};
 
// render thread
class FSubsurfaceProfileTexture : public FRenderResource
{
public:
    // constructor
    FSubsurfaceProfileTexture();
 
    // destructor
    ~FSubsurfaceProfileTexture();
 
    // convenience, can be optimized 
    // @param Profile must not be 0, game thread pointer, do not dereference, only for comparison
    int32 AddOrUpdateProfile(const FSubsurfaceProfileStruct Settings, const USubsurfaceProfile* Profile)
    {
        check(Profile);
 
        int32 AllocationId = FindAllocationId(Profile); 
        
        if (AllocationId != -1)
        {
            UpdateProfile(AllocationId, Settings);
        }
        else
        {
            AllocationId = AddProfile(Settings, Profile);
        }
 
        return AllocationId;
    }
 
    // O(n) n is a small number
    // @param InProfile must not be 0, game thread pointer, do not dereference, only for comparison
    // @return AllocationId -1: no allocation, should be deallocated with DeallocateSubsurfaceProfile()
    int32 AddProfile(const FSubsurfaceProfileStruct Settings, const USubsurfaceProfile* InProfile);
 
    // O(n) to find the element, n is the SSProfile count and usually quite small
    void RemoveProfile(const USubsurfaceProfile* InProfile);
 
    // @param InProfile must not be 0, game thread pointer, do not dereference, only for comparison
    void UpdateProfile(const FSubsurfaceProfileStruct Settings, const USubsurfaceProfile* Profile) { int32 AllocationId = FindAllocationId(Profile); UpdateProfile(AllocationId, Settings); }
 
    // @param InProfile must not be 0, game thread pointer, do not dereference, only for comparison
    void UpdateProfile(int32 AllocationId, const FSubsurfaceProfileStruct Settings);
 
    // @return can be 0 if there is no SubsurfaceProfile
    struct IPooledRenderTarget* GetTexture(FRHICommandListImmediate& RHICmdList);
    struct IPooledRenderTarget* GetTexture();
 
    struct IPooledRenderTarget* GetSSProfilesPreIntegratedTexture(class FRDGBuilder& GraphBuilder, EShaderPlatform ShaderPlatform);
 
    //~ Begin FRenderResource Interface.
    virtual void ReleaseRHI() override;
 
    // for debugging, can be removed
    void Dump();
 
    // for debugging / VisualizeSSS
    ENGINE_API bool GetEntryString(uint32 Index, FString& Out) const;
 
    // @param InProfile must not be 0, game thread pointer, do not dereference, only for comparison
    // @return -1 if not found
    int32 FindAllocationId(const USubsurfaceProfile* InProfile) const;
 
private:
 
    struct FSubsurfaceProfileEntry
    {
        // @param InProfile game thread pointer, do not dereference, only for comparison, 0 if the entry can be reused or it's [0] which is used as default
        FSubsurfaceProfileEntry(FSubsurfaceProfileStruct InSubsurfaceProfileStruct, const USubsurfaceProfile* InProfile)
            : Settings(InSubsurfaceProfileStruct)
            , Profile(InProfile)
        {
        }
 
        FSubsurfaceProfileStruct Settings;
 
        // 0 if the entry can be reused or it's [0] which is used as default
        // game thread pointer, do not dereference, only for comparison
        const USubsurfaceProfile* Profile;
    };
 
    //
    TArray<FSubsurfaceProfileEntry> SubsurfaceProfileEntries;
 
    // Could be optimized but should not happen too often (during level load or editor operations).
    void CreateTexture(FRHICommandListImmediate& RHICmdList);
 
};
 
// If you change this you need to recompile the SSS shaders.
// Required if we use a texture format with limited size but want to express a larger radius
static const int32 SUBSURFACE_RADIUS_SCALE = 1024;
 
 // The kernels range from -3 to 3
static const int32 SUBSURFACE_KERNEL_SIZE = 3;
 
// lives on the render thread
extern ENGINE_API TGlobalResource<FSubsurfaceProfileTexture> GSubsurfaceProfileTextureObject;
 
// Initializes or updates the contents of the subsurface profile texture.
UE_DEPRECATED(5.5, "Please, use the name space SubsurfaceProfile::")
ENGINE_API void UpdateSubsurfaceProfileTexture(class FRDGBuilder& GraphBuilder, EShaderPlatform ShaderPlatform);
 
// Returns the subsurface profile texture if it exists, or null.
UE_DEPRECATED(5.5, "Please, use the name space SubsurfaceProfile::")
ENGINE_API FRHITexture* GetSubsurfaceProfileTexture();
 
// Returns the subsurface profile texture if it exists, or black.
UE_DEPRECATED(5.5, "Please, use the name space SubsurfaceProfile::")
ENGINE_API FRHITexture* GetSubsurfaceProfileTextureWithFallback();
 
// Returns the Preintegrated texture if it exists, or black.
UE_DEPRECATED(5.5, "Please, use the name space SubsurfaceProfile::")
ENGINE_API FRHITexture* GetSSProfilesPreIntegratedTextureWithFallback();
 
// Returns the subsurface profile ID shader parameter name
UE_DEPRECATED(5.5, "Please, use the name space SubsurfaceProfile::")
ENGINE_API FName GetSubsurfaceProfileParameterName();
 
// Returns the subsurface profile ID for a given Sub-surface Profile object
UE_DEPRECATED(5.5, "Please, use the name space SubsurfaceProfile::")
ENGINE_API float GetSubsurfaceProfileId(const USubsurfaceProfile* In);
 
// Returns the shader parameter name for a Subsurface profile.
UE_DEPRECATED(5.5, "Please, use the name space SubsurfaceProfile::")
ENGINE_API FName CreateSubsurfaceProfileParameterName(const USubsurfaceProfile* InProfile);
 
namespace SubsurfaceProfile
{
// Initializes or updates the contents of the subsurface profile texture.
ENGINE_API void UpdateSubsurfaceProfileTexture(class FRDGBuilder& GraphBuilder, EShaderPlatform ShaderPlatform);
 
// Returns the subsurface profile texture if it exists, or null.
ENGINE_API FRHITexture* GetSubsurfaceProfileTexture();
 
// Returns the subsurface profile texture if it exists, or black.
ENGINE_API FRHITexture* GetSubsurfaceProfileTextureWithFallback();
 
// Returns the Preintegrated texture if it exists, or black.
ENGINE_API FRHITexture* GetSSProfilesPreIntegratedTextureWithFallback();
 
// Returns the subsurface profile ID shader parameter name
ENGINE_API FName GetSubsurfaceProfileParameterName();
 
// Returns the subsurface profile ID for a given Sub-surface Profile object
ENGINE_API float GetSubsurfaceProfileId(const USubsurfaceProfile* In);
 
// Returns the shader parameter name for a Subsurface profile.
ENGINE_API FName CreateSubsurfaceProfileParameterName(const USubsurfaceProfile* InProfile);
};