ISMComponentBatcher.h

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// Copyright Epic Games, Inc. All Rights Reserved.
#pragma once
 
#include "CoreMinimal.h"
#include "Components/InstancedStaticMeshComponent.h"
#include "Engine/EngineTypes.h"
#include "Templates/EnableIf.h"
#include "Templates/UnrealTypeTraits.h"
 
class UInstancedStaticMeshComponent;
class UInstancedSkinnedMeshComponent;
 
struct FISMComponentBatcher
{
public:
    FISMComponentBatcher()
    {
    }
 
    FISMComponentBatcher(bool bInBuildMappingInfo)
        : bBuildMappingInfo(bInBuildMappingInfo)
    {
    }
 
    ENGINE_API void Add(const UActorComponent* InActorComponent);
 
    ENGINE_API void Add(const UActorComponent* InActorComponent, TFunctionRef<FTransform(const FTransform&)> InTransformFunc);
 
    ENGINE_API void Add(const UActorComponent* InComponent, TFunctionRef<bool(const FBox&)> InFilterFunc);
 
    ENGINE_API void Add(const UActorComponent* InComponent, TFunctionRef<FTransform(const FTransform&)> InTransformFunc, TFunctionRef<bool(const FBox&)> InFilterFunc);
    
    template<typename TComponentClass = UActorComponent, typename = typename TEnableIf<TIsDerivedFrom<TComponentClass, UActorComponent>::IsDerived>::Type>
    void Append(const TArray<TComponentClass*>& InComponents)
    {
        for (const UActorComponent* InComponent : InComponents)
        {
            Add(InComponent);
        }
    }
 
    template<typename TComponentClass = UActorComponent, typename = typename TEnableIf<TIsDerivedFrom<TComponentClass, UActorComponent>::IsDerived>::Type>
    void Append(const TArray<TComponentClass*>& InComponents, TFunctionRef<FTransform(const FTransform&)> InTransformFunc)
    {
        for (const UActorComponent* InComponent : InComponents)
        {
            Add(InComponent, InTransformFunc);
        }
    }
 
    template<typename TComponentClass = UActorComponent, typename = typename TEnableIf<TIsDerivedFrom<TComponentClass, UActorComponent>::IsDerived>::Type>
    void Append(const TArray<TComponentClass*>& InComponents, TFunctionRef<bool(const FBox&)> InFilterFunc)
    {
        for (const UActorComponent* InComponent : InComponents)
        {
            Add(InComponent, InFilterFunc);
        }
    }
 
    template<typename TComponentClass = UActorComponent, typename = typename TEnableIf<TIsDerivedFrom<TComponentClass, UActorComponent>::IsDerived>::Type>
    void Append(const TArray<TComponentClass*>& InComponents, TFunctionRef<FTransform(const FTransform&)> InTransformFunc, TFunctionRef<bool(const FBox&)> InFilterFunc)
    {
        for (const UActorComponent* InComponent : InComponents)
        {
            Add(InComponent, InTransformFunc, InFilterFunc);
        }
    }
 
    int32 GetNumInstances() const { return NumInstances; }
 
    ENGINE_API void InitComponent(UInstancedStaticMeshComponent* ISMComponent) const;
 
    ENGINE_API void InitComponent(UInstancedSkinnedMeshComponent* ISMComponent) const;
    
    inline uint32 GetHash() const
    {
        if (Hash == 0)
        {
            ComputeHash();
        }
        return Hash;
    }
 
    struct FComponentToInstancesMapping
    {
        const UActorComponent* Component;
        uint32 InstancesStart;
        uint32 InstancesCount;
    };
 
    ENGINE_API TArray<FComponentToInstancesMapping> GetComponentsToInstancesMap();
    
protected:
    void ENGINE_API AddInternal(const UActorComponent* InComponent, TOptional<TFunctionRef<FTransform(const FTransform&)>> InTransformFunc, TOptional<TFunctionRef<bool(const FBox&)>> InFilterFunc);
    void ENGINE_API ComputeHash() const;
 
    mutable uint32 Hash = 0;
    int32 NumInstances = 0;
    int32 NumCustomDataFloats = 0;
 
    TArray<FTransform> InstancesTransformsWS;
    TArray<float> InstancesCustomData;
 
    // For ISMC only
    int32 InstancingRandomSeed = 0;
    TArray<FInstancedStaticMeshRandomSeed> AdditionalRandomSeeds; 
 
    // For ISKMC only
    TArray<int32> AnimationIndices;
 
    // Mapping info to be able to use GetComponentsToInstancesMap() to retrieve the range of instances associated with a component added to the ISM batcher.
    bool bBuildMappingInfo = false;
    TArray<FComponentToInstancesMapping> ComponentsToInstancesMap;
};