MassRelationCommands.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "MassCommands.h"
#include "MassEntityManager.h"
 
#if CSV_PROFILER_STATS || WITH_MASSENTITY_DEBUG
#   define DEBUG_NAME(Name) , FName(TEXT(Name))
#   define DEBUG_NAME_PARAM(Name) , const FName InDebugName = TEXT(Name)
#   define FORWARD_DEBUG_NAME_PARAM , InDebugName
#else
#   define DEBUG_NAME(Name)
#   define DEBUG_NAME_PARAM(Name)
#   define FORWARD_DEBUG_NAME_PARAM
#endif // CSV_PROFILER_STATS || WITH_MASSENTITY_DEBUG
 
template<typename TRelation>
struct FMassCommandMakeRelation : public FMassBatchedEntityCommand
{
    using Super = FMassBatchedEntityCommand;
 
    FMassCommandMakeRelation(EMassCommandOperationType OperationType = EMassCommandOperationType::Add DEBUG_NAME_PARAM("MakeRelation"))
        : Super(OperationType FORWARD_DEBUG_NAME_PARAM)
    {}
 
    void Add(const FMassEntityHandle ChildEntity, const FMassEntityHandle ParentEntity)
    {
        Super::Add(ChildEntity);
        Parents.Add(ParentEntity);
    }
 
    void Add(TConstArrayView<FMassEntityHandle> ChildEntities, TConstArrayView<FMassEntityHandle> ParentEntities)
    {
        ensure(ChildEntities.Num() != 0 && ParentEntities.Num() != 0);
 
        Super::Add(ChildEntities);
 
        if (ChildEntities.Num() > ParentEntities.Num())
        {
            // @todo to be improved - we should have a dedicated path for Multi-children -> Single parent  operations
            do
            {
                Parents.Append(ParentEntities.GetData(), ParentEntities.Num());
            } while (Parents.Num() < TargetEntities.Num());
            Parents.SetNum(TargetEntities.Num(), EAllowShrinking::No);
        }
        else
        {
            Parents.Append(ParentEntities.GetData(), FMath::Min(ParentEntities.Num(), ChildEntities.Num()));
        }
    }
 
protected:
    virtual void Reset() override
    {
        Parents.Reset();
        Super::Reset();
    }
 
    virtual SIZE_T GetAllocatedSize() const override
    {
        return Super::GetAllocatedSize() + Parents.GetAllocatedSize();
    }
 
    virtual void Run(FMassEntityManager& EntityManager) override
    {
        TRACE_CPUPROFILER_EVENT_SCOPE(FMassCommandMakeRelation_Execute);
        EntityManager.BatchCreateRelations<TRelation>(TargetEntities, Parents);
    }
 
    TArray<FMassEntityHandle> Parents;
};
 
#undef DEBUG_NAME
#undef DEBUG_NAME_PARAM
#undef FORWARD_DEBUG_NAME_PARAM