MaterialExpressionLayerStack.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "CoreMinimal.h"
#include "UObject/ObjectMacros.h"
#include "UObject/SoftObjectPath.h"
#include "MaterialExpressionIO.h"
#include "Materials/MaterialExpression.h"
#include "Materials/MaterialExpressionFunctionInput.h"
#include "Materials/MaterialExpressionMaterialAttributeLayers.h"
#include "Materials/MaterialLayersFunctions.h"
#include "MaterialExpressionLayerStack.generated.h"
 
class FMaterialCompiler;
class UMaterialFunctionInterface;
 
USTRUCT(Experimental)
struct FMaterialLayerInput : public FExpressionInput
{
    GENERATED_BODY()
 
    UPROPERTY()
    TEnumAsByte<EFunctionInputType> InputType;
 
    FMaterialLayerInput(FName NewInputName = NAME_None, EFunctionInputType NewInputType = FunctionInput_MAX);
    FString GetInputName() const;
};
 
UCLASS(hidecategories = Object, MinimalAPI, Experimental)
class UMaterialExpressionLayerStack : public UMaterialExpressionMaterialAttributeLayers
{
    GENERATED_UCLASS_BODY()
 
    UPROPERTY()
    TArray<FMaterialLayerInput> LayerInputs;
 
    UPROPERTY(EditAnywhere, Category = AvailableFunctions, meta = (DisallowedClasses = "/Script/Engine.MaterialFunctionMaterialLayerBlend, /Script/Engine.MaterialFunctionMaterialLayerBlendInstance"))
    TSet<TObjectPtr<UMaterialFunctionInterface>> AvailableLayers;
 
    UPROPERTY(EditAnywhere, Category = AvailableFunctions, meta = (AllowedClasses = "/Script/Engine.MaterialFunctionMaterialLayerBlend, /Script/Engine.MaterialFunctionMaterialLayerBlendInstance"))
    TSet<TObjectPtr<UMaterialFunctionInterface>> AvailableBlends;
 
    //~ Begin UObject Interface
    virtual void PostLoad() override;
    virtual void PreSave(FObjectPreSaveContext ObjectSaveContext) override;
    //~ End UObject Interface
 
#if WITH_EDITOR
    //~ Begin UMaterialExpression Interface
    virtual void PostEditChangeProperty(FPropertyChangedEvent& PropertyChangedEvent) override;
    virtual void GetCaption(TArray<FString>& OutCaptions) const override;
    virtual void GetExpressionToolTip(TArray<FString>& OutToolTip) override;
    virtual FName GetInputName(int32 InputIndex) const override;
    virtual FExpressionInput* GetInput(int32 InputIndex) override;
    virtual TArrayView<FExpressionInput*> GetInputsView() override;
    virtual EMaterialValueType GetInputValueType(int32 InputIndex) override;
    //~ End UMaterialExpression Interface
 
    //~ Begin UMaterialExpressionMaterialAttributeLayers Interface
    virtual bool ValidateLayerConfiguration(FMaterialCompiler* Compiler, bool bReportErrors) override;
    ENGINE_API virtual void RebuildLayerGraph(bool bReportErrors);
    //~ End UMaterialExpressionMaterialAttributeLayers Interface
 
    //This struct is to circumvent having to extend the below lambda in future if we want to validate against additional node types.
    struct FValidLayerUsageTracker
    {
        int32 MAInputCount = 0;
        int32 MAOutputCount = 0;
        bool bContainsStatics = false;
    };
 
    static UMaterialFunctionInterface* ExtractParentFunctionFromInstance(class FMaterialCompiler* Compiler, UMaterialFunctionInterface* CurrentFunction);
    static bool PollFunctionExpressionsForLayerUsage(class FMaterialCompiler* Compiler, UMaterialFunctionInterface* CurrentFunction, FValidLayerUsageTracker& Tracker, bool bCheckStatics);
    static bool ValidateFunctionForLayerUsage(class FMaterialCompiler* Compiler, UMaterialFunctionInterface* CurrentFunction, bool bCheckStatics = false);
    static bool ValidateFunctionForBlendUsage(class FMaterialCompiler* Compiler, UMaterialFunctionInterface* CurrentFunction, bool bCheckStatics = false);
 
    TSharedPtr<FMaterialLayerStackFunctionsCache> GetSharedAvailableFunctionsCache();
    void ResolveLayerInputs();
    void CacheLayerInputs();
#endif
    inline TArray<FSoftObjectPath> GetAvailableLayerPaths() { return GetPathsFromAvailableFunctions(AvailableLayers); }
    inline TArray<FSoftObjectPath> GetAvailableBlendPaths() { return GetPathsFromAvailableFunctions(AvailableBlends); }
 
private:
    TSharedPtr<FMaterialLayerStackFunctionsCache> SharedCache;
    bool bAreAvailableLayersValid = false;
 
    static TArray<FSoftObjectPath> GetPathsFromAvailableFunctions(TSet<TObjectPtr<UMaterialFunctionInterface>>& InFunctions);
};