LargeWorldCoordinatesSerializer.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
#include "UObject/NameTypes.h"
#include "UObject/ObjectVersion.h"
#include "Serialization/StructuredArchive.h"
 
// Serialization helper for core variant types only. DO NOT USE!
#define UE_SERIALIZE_VARIANT_FROM_MISMATCHED_TAG(AR_OR_SLOT, ALIAS, TYPE, ALT_TYPE) LWCSerializerPrivate::SerializeFromMismatchedTag<F##ALT_TYPE>(*this, StructTag, AR_OR_SLOT, NAME_##ALIAS, NAME_##TYPE, NAME_##ALT_TYPE)
namespace LWCSerializerPrivate
{
 
inline bool IsPreLWC(const FArchive& Ar) { return Ar.UEVer() < EUnrealEngineObjectUE5Version::LARGE_WORLD_COORDINATES; } 
inline bool IsPreLWC(const FStructuredArchive::FSlot& Slot) { return IsPreLWC(Slot.GetUnderlyingArchive()); } 
 
// SerializeFromMismatchedTag helper for core type use only. DO NOT USE!
template<typename FAltType, typename FType, typename FArSlot>
std::enable_if_t<std::is_floating_point_v<typename FType::FReal>, bool>  SerializeFromMismatchedTag(FType& Target, FName StructTag, FArSlot& ArSlot, FName BaseTag, FName ThisTag, FName AltTag)
{
    if(StructTag == ThisTag || (StructTag == BaseTag && (TIsUECoreVariant<FType, double>::Value || IsPreLWC(ArSlot))))
    {
        // Note: relies on Serialize to handle float/double based on archive version.
        return Target.Serialize(ArSlot);
    }
    else if(StructTag == AltTag || StructTag == BaseTag)
    {
        // Convert from alt type
        FAltType AsAlt;                                     // TODO: Could we derive this from FType?
        const bool bResult = AsAlt.Serialize(ArSlot);
        Target = static_cast<FType>(AsAlt);                 // LWC_TODO: Log precision loss warning for TIsUECoreVariant<FType, float>? Could get spammy.
        return bResult;
    }
 
    return false;
}
 
// SerializeFromMismatchedTag helper for core type use only. DO NOT USE!
template<typename FAltType, typename FType, typename FArSlot>
std::enable_if_t<std::is_integral_v<typename FType::IntType>, bool> SerializeFromMismatchedTag(FType& Target, FName StructTag, FArSlot& ArSlot, FName BaseTag, FName ThisTag, FName AltTag)
{
    if (StructTag == ThisTag || (StructTag == BaseTag && (TIsUECoreVariant<FType, int32>::Value || TIsUECoreVariant<FType, uint32>::Value)))
    {
        // Note: Unlike float types int retains a default of 32bits, so no conversion is necessary.
        return Target.Serialize(ArSlot);
    }
    else if (StructTag == AltTag || StructTag == BaseTag)
    {
        // Convert from alt type
        FAltType AsAlt;
        const bool bResult = AsAlt.Serialize(ArSlot);
        Target = static_cast<FType>(AsAlt);
        return bResult;
    }
 
    return false;
}
 
} // namespace LWCSerializerPrivate