MaterialAggregate.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "CoreMinimal.h"
#include "MaterialValueType.h"
#include "Engine/DataAsset.h"
#include "SceneTypes.h"
#include "MaterialAggregate.generated.h"
 
class UMaterialAggregate;
 
// Specifies the type of an individual material aggregate attribute.
UENUM()
enum class EMaterialAggregateAttributeType
{
    Bool1,
    Bool2,
    Bool3,
    Bool4,
    
    UInt1,
    UInt2,
    UInt3,
    UInt4,
 
    Float1,
    Float2,
    Float3,
    Float4,
 
    // Attribute is a shading mode. Used in by MaterialAttributes aggregate.
    ShadingModel,
 
    // Attribute is of type MaterialAttributes aggregate.
    MaterialAttributes,
 
    // Attribute is of specified user aggregate type.
    Aggregate,
};
 
#if WITH_EDITOR
 
// Converts a EMaterialValueType to the equivalent EMaterialAggregateAttributeTypeKind, if possible.
EMaterialAggregateAttributeType MaterialValueTypeToMaterialAggregateAttributeType(EMaterialValueType Type);
 
#endif
 
// Represents a single attribute within a material aggregate.
USTRUCT(MinimalAPI)
struct FMaterialAggregateAttribute
{
    GENERATED_BODY()
 
    // The name of the attribute.
    UPROPERTY(EditAnywhere, Category=MaterialAggregateAttribute)
    FName Name{};
 
    // The type of the attribute.
    UPROPERTY(EditAnywhere, Category=MaterialAggregateAttribute)
    EMaterialAggregateAttributeType Type = EMaterialAggregateAttributeType::Float4;
 
    // The nested aggregate reference, used only if TypeKind is Aggregate.
    UPROPERTY(EditAnywhere, Category=MaterialAggregateAttribute, meta=(EditCondition="Type == EMaterialAggregateAttributeType::Aggregate", EditConditionHides))
    TObjectPtr<UMaterialAggregate> Aggregate{};
 
    // This attribute default value, assigned when the parent aggregate is constructed without an assignment to this attribute.
    UPROPERTY(EditAnywhere, Category=MaterialAggregateAttribute)
    FVector4f DefaultValue;
 
#if WITH_EDITOR
    // Converts this attribute's type to a corresponding material value type.
    EMaterialValueType ToMaterialValueType() const;
#endif
};
 
// It defines a collection of arithmetic material values to be bundled together.
// A material aggregate works similarly to a struct in C/C++. Each attribute has a name and specifies a type, either a
// primitive one like float4 or another aggregate (for nested structures).
UCLASS(MinimalAPI)
class UMaterialAggregate : public UDataAsset
{
    GENERATED_BODY()
 
public:
    // List of material aggregate attributes.
    UPROPERTY(EditAnywhere, Category=MaterialAggregate)
    TArray<FMaterialAggregateAttribute> Attributes;
 
public:
#if WITH_EDITOR
 
    static const TConstArrayView<EMaterialProperty> GetMaterialAttributesProperties();
 
    // Returns a reference to the global material attributes aggregate used by the engine.
    static const UMaterialAggregate* GetMaterialAttributes();
 
    // Returns a single cached aggregate for the specified material property.
    static const FMaterialAggregateAttribute* GetMaterialAttribute(EMaterialProperty Property);
 
    // Maps a material property to the corresponding attribute index in the aggregate.
    static int32 MaterialPropertyToAttributeIndex(EMaterialProperty Property);
 
    // Maps an attribute index back to the corresponding material property.
    static EMaterialProperty AttributeIndexToMaterialProperty(int32 MaterialAttributeIndex);
 
    static inline bool IsMaterialPropertyEnabled(EMaterialProperty Property)
    {
        return MaterialPropertyToAttributeIndex(Property) != INDEX_NONE;
    }
 
    // Finds the index of an attribute in the aggregate by name.
    int32 FindAttributeIndexByName(FName Name) const;
 
    virtual void PostLoad() override;
    virtual void PostEditChangeProperty(FPropertyChangedEvent& PropertyChangedEvent) override;
 
#endif // #if WITH_EDITOR
};