EM_Task/UnrealEd/Private/FbxMeshUtils.cpp

// Copyright Epic Games, Inc. All Rights Reserved.

#include "FbxMeshUtils.h"
#include "EngineDefines.h"
#include "Misc/Paths.h"
#include "UObject/Package.h"
#include "Engine/SkeletalMesh.h"
#include "Factories/FbxAssetImportData.h"
#include "Factories/FbxSkeletalMeshImportData.h"
#include "Factories/FbxStaticMeshImportData.h"
#include "Factories/FbxImportUI.h"
#include "Engine/StaticMesh.h"
#include "EditorDirectories.h"
#include "Framework/Application/SlateApplication.h"
#include "Misc/MessageDialog.h"
#include "ComponentReregisterContext.h"
#include "Logging/TokenizedMessage.h"
#include "FbxImporter.h"
#include "StaticMeshResources.h"
#include "Components/SkeletalMeshComponent.h"
#include "Rendering/SkeletalMeshModel.h"
#include "EditorFramework/AssetImportData.h"
#include "DesktopPlatformModule.h"
#include "Editor.h"
#include "ImportUtils/SkeletalMeshImportUtils.h"
#include "ImportUtils/StaticMeshImportUtils.h"

#if WITH_APEX_CLOTHING
#include "ApexClothingUtils.h"
#endif  // #if WITH_APEX_CLOTHING

#include "Misc/FbxErrors.h"
#include "Framework/Notifications/NotificationManager.h"
#include "Widgets/Notifications/SNotificationList.h"

#include "ClothingAsset.h"
#include "SkinWeightsUtilities.h"
#include "LODUtilities.h"

DEFINE_LOG_CATEGORY_STATIC(LogExportMeshUtils, Log, All);

#define LOCTEXT_NAMESPACE "FbxMeshUtil"

namespace FbxMeshUtils
{
/** Helper function used for retrieving data required for importing static mesh LODs */
void PopulateFBXStaticMeshLODList(UnFbx::FFbxImporter* FFbxImporter, FbxNode* Node, TArray<TArray<FbxNode*>*>& LODNodeList, int32& MaxLODCount, bool bUseLODs)
{
    // Check for LOD nodes, if one is found, add it to the list
    if (bUseLODs && Node->GetNodeAttribute() && Node->GetNodeAttribute()->GetAttributeType() == FbxNodeAttribute::eLODGroup)
    {
        for (int32 ChildIdx = 0; ChildIdx < Node->GetChildCount(); ++ChildIdx)
        {
            if ((LODNodeList.Num() - 1) < ChildIdx)
            {
                TArray<FbxNode*>* NodeList = new TArray<FbxNode*>;
                LODNodeList.Add(NodeList);
            }
            FFbxImporter->FindAllLODGroupNode(*(LODNodeList[ChildIdx]), Node, ChildIdx);
        }

        if (MaxLODCount < (Node->GetChildCount() - 1))
        {
            MaxLODCount = Node->GetChildCount() - 1;
        }
    }
    else
    {
        // If we're just looking for meshes instead of LOD nodes, add those to the list
        if (!bUseLODs && Node->GetMesh())
        {
            if (LODNodeList.Num() == 0)
            {
                TArray<FbxNode*>* NodeList = new TArray<FbxNode*>;
                LODNodeList.Add(NodeList);
            }

            LODNodeList[0]->Add(Node);
        }

        // Recursively examine child nodes
        for (int32 ChildIndex = 0; ChildIndex < Node->GetChildCount(); ++ChildIndex)
        {
            PopulateFBXStaticMeshLODList(FFbxImporter, Node->GetChild(ChildIndex), LODNodeList, MaxLODCount, bUseLODs);
        }
    }
}

bool ImportStaticMeshLOD(UStaticMesh* BaseStaticMesh, const FString& Filename, int32 LODLevel)
{
    bool bSuccess = false;

    UE_LOG(LogExportMeshUtils, Log, TEXT("Fbx LOD loading"));
    // logger for all error/warnings
    // this one prints all messages that are stored in FFbxImporter
    // this function seems to get called outside of FBX factory
    UnFbx::FFbxImporter* FFbxImporter = UnFbx::FFbxImporter::GetInstance();
    UnFbx::FFbxLoggerSetter Logger(FFbxImporter);

    UnFbx::FBXImportOptions* ImportOptions = FFbxImporter->GetImportOptions();

    bool IsReimport                        = BaseStaticMesh->GetRenderData()->LODResources.Num() > LODLevel;
    UFbxStaticMeshImportData* ImportData   = Cast<UFbxStaticMeshImportData>(BaseStaticMesh->AssetImportData);
    if (ImportData != nullptr)
    {

        UFbxImportUI* ReimportUI     = NewObject<UFbxImportUI>();
        ReimportUI->MeshTypeToImport = FBXIT_StaticMesh;
        UnFbx::FBXImportOptions::ResetOptions(ImportOptions);
        // Import data already exists, apply it to the fbx import options
        ReimportUI->StaticMeshImportData = ImportData;
        ApplyImportUIToImportOptions(ReimportUI, *ImportOptions);
        ImportOptions->bIsImportCancelable = false;
        ImportOptions->bImportMaterials    = false;
        ImportOptions->bImportTextures     = false;
        // Make sure the LODGroup do not change when re-importing a mesh
        ImportOptions->StaticMeshLODGroup = BaseStaticMesh->LODGroup;
    }
    ImportOptions->bAutoComputeLodDistances = true;  // Setting auto compute distance to true will avoid changing the staticmesh flag
    if (!FFbxImporter->ImportFromFile(*Filename, FPaths::GetExtension(Filename), true))
    {
        // Log the error message and fail the import.
        // @todo verify if the message works
        FFbxImporter->FlushToTokenizedErrorMessage(EMessageSeverity::Error);
    }
    else
    {
        FFbxImporter->FlushToTokenizedErrorMessage(EMessageSeverity::Warning);
        if (ImportData)
        {
            FFbxImporter->ApplyTransformSettingsToFbxNode(FFbxImporter->Scene->GetRootNode(), ImportData);
        }

        bool bUseLODs     = true;
        int32 MaxLODLevel = 0;
        TArray<TArray<FbxNode*>*> LODNodeList;

        // Create a list of LOD nodes
        PopulateFBXStaticMeshLODList(FFbxImporter, FFbxImporter->Scene->GetRootNode(), LODNodeList, MaxLODLevel, bUseLODs);

        // No LODs, so just grab all of the meshes in the file
        if (MaxLODLevel == 0)
        {
            bUseLODs    = false;
            MaxLODLevel = BaseStaticMesh->GetNumLODs();

            // Create a list of meshes
            PopulateFBXStaticMeshLODList(FFbxImporter, FFbxImporter->Scene->GetRootNode(), LODNodeList, MaxLODLevel, bUseLODs);

            // Nothing found, error out
            if (LODNodeList.Num() == 0)
            {
                FFbxImporter->AddTokenizedErrorMessage(FTokenizedMessage::Create(EMessageSeverity::Error, FText(LOCTEXT("Prompt_NoMeshFound", "No meshes were found in file."))), FFbxErrors::Generic_Mesh_MeshNotFound);

                FFbxImporter->ReleaseScene();
                return bSuccess;
            }
        }

        TSharedPtr<FExistingStaticMeshData> ExistMeshDataPtr;
        if (IsReimport)
        {
            ExistMeshDataPtr = StaticMeshImportUtils::SaveExistingStaticMeshData(BaseStaticMesh, FFbxImporter->ImportOptions, LODLevel);
        }

        // Display the LOD selection dialog
        if (LODLevel > BaseStaticMesh->GetNumLODs())
        {
            // Make sure they don't manage to select a bad LOD index
            FFbxImporter->AddTokenizedErrorMessage(FTokenizedMessage::Create(EMessageSeverity::Warning, FText::Format(LOCTEXT("Prompt_InvalidLODIndex", "Invalid mesh LOD index {0}, as no prior LOD index exists!"), FText::AsNumber(LODLevel))), FFbxErrors::Generic_Mesh_LOD_InvalidIndex);
        }
        else
        {
            UStaticMesh* TempStaticMesh = NULL;
            if (!LODNodeList.IsValidIndex(bUseLODs ? LODLevel : 0))
            {
                if (bUseLODs)
                {
                    // Use the first LOD when user try to add or re-import a LOD from a file(different from the LOD 0 file) containing multiple LODs
                    bUseLODs = false;
                }
            }

            if (LODNodeList.IsValidIndex(bUseLODs ? LODLevel : 0))
            {
                TempStaticMesh = (UStaticMesh*)FFbxImporter->ImportStaticMeshAsSingle(BaseStaticMesh->GetOutermost(), *(LODNodeList[bUseLODs ? LODLevel : 0]), NAME_None, RF_NoFlags, ImportData, BaseStaticMesh, LODLevel, ExistMeshDataPtr.Get());
            }

            // Add imported mesh to existing model
            if (TempStaticMesh)
            {
                // Build the staticmesh
                FFbxImporter->PostImportStaticMesh(TempStaticMesh, *(LODNodeList[bUseLODs ? LODLevel : 0]), LODLevel);
                TArray<int32> ReimportLodList;
                ReimportLodList.Add(LODLevel);
                StaticMeshImportUtils::UpdateSomeLodsImportMeshData(BaseStaticMesh, &ReimportLodList);
                if (IsReimport)
                {
                    StaticMeshImportUtils::RestoreExistingMeshData(ExistMeshDataPtr, BaseStaticMesh, LODLevel, false, ImportOptions->bResetToFbxOnMaterialConflict);
                }

                // Update mesh component
                BaseStaticMesh->PostEditChange();
                BaseStaticMesh->MarkPackageDirty();

                // Import worked
                FNotificationInfo NotificationInfo(FText::GetEmpty());
                NotificationInfo.Text           = FText::Format(LOCTEXT("LODImportSuccessful", "Mesh for LOD {0} imported successfully!"), FText::AsNumber(LODLevel));
                NotificationInfo.ExpireDuration = 5.0f;
                FSlateNotificationManager::Get().AddNotification(NotificationInfo);
                if (BaseStaticMesh->IsSourceModelValid(LODLevel))
                {
                    FStaticMeshSourceModel& SourceModel = BaseStaticMesh->GetSourceModel(LODLevel);
                    SourceModel.SourceImportFilename    = UAssetImportData::SanitizeImportFilename(Filename, nullptr);
                    SourceModel.bImportWithBaseMesh     = false;
                }
                bSuccess = true;
            }
            else
            {
                // Import failed
                FNotificationInfo NotificationInfo(FText::GetEmpty());
                NotificationInfo.Text           = FText::Format(LOCTEXT("LODImportFail", "Failed to import mesh for LOD {0}!"), FText::AsNumber(LODLevel));
                NotificationInfo.ExpireDuration = 5.0f;
                FSlateNotificationManager::Get().AddNotification(NotificationInfo);

                bSuccess = false;
            }
        }

        // Cleanup
        for (int32 i = 0; i < LODNodeList.Num(); ++i)
        {
            delete LODNodeList[i];
        }
    }
    FFbxImporter->ReleaseScene();

    return bSuccess;
}

bool ImportSkeletalMeshLOD(class USkeletalMesh* SelectedSkelMesh, const FString& Filename, int32 LODLevel)
{
    UnFbx::FFbxImporter* FFbxImporter = UnFbx::FFbxImporter::GetInstance();
    // Make sure skeletal mesh is valid
    if (!SelectedSkelMesh)
    {
        FFbxImporter->AddTokenizedErrorMessage(FTokenizedMessage::Create(EMessageSeverity::Error, LOCTEXT("FBXImport_NoSelectedSkeletalMesh", "Cannot import a LOD if there is not a valid selected skeletal mesh.")), FFbxErrors::Generic_MeshNotFound);
        return false;
    }

    bool bSuccess = false;

    // Check the file extension for FBX. Anything that isn't .FBX is rejected
    const FString FileExtension = FPaths::GetExtension(Filename);
    const bool bIsFBX           = FCString::Stricmp(*FileExtension, TEXT("FBX")) == 0;
    bool bSceneIsCleanUp        = false;
    TArray<TArray<FbxNode*>*> MeshArray;
    auto CleanUpScene = [&bSceneIsCleanUp, &MeshArray, &FFbxImporter]()
    {
        if (bSceneIsCleanUp)
        {
            return;
        }
        bSceneIsCleanUp = true;
        // Cleanup
        for (int32 i = 0; i < MeshArray.Num(); i++)
        {
            delete MeshArray[i];
        }
        FFbxImporter->ReleaseScene();
        FFbxImporter = nullptr;
    };

    // Skip none fbx file
    if (!bIsFBX)
    {
        return false;
    }

    FScopedSkeletalMeshPostEditChange ScopePostEditChange(SelectedSkelMesh);
    UnFbx::FFbxScopedOperation FbxScopedOperation(FFbxImporter);

    // If the imported LOD already exist, we will need to reimport all the skin weight profiles
    bool bMustReimportAlternateSkinWeightProfile = false;

    // Get a list of all the clothing assets affecting this LOD so we can re-apply later
    TArray<ClothingAssetUtils::FClothingAssetMeshBinding> ClothingBindings;
    TArray<UClothingAssetBase*> ClothingAssetsInUse;
    TArray<int32> ClothingAssetSectionIndices;
    TArray<int32> ClothingAssetInternalLodIndices;

    FSkeletalMeshModel* ImportedResource = SelectedSkelMesh->GetImportedModel();
    if (ImportedResource && ImportedResource->LODModels.IsValidIndex(LODLevel))
    {
        bMustReimportAlternateSkinWeightProfile = true;
        FLODUtilities::UnbindClothingAndBackup(SelectedSkelMesh, ClothingBindings, LODLevel);
    }

    // Lambda to call to re-apply the clothing
    auto ReapplyClothing = [&SelectedSkelMesh, &ClothingBindings, &ImportedResource, &LODLevel]()
    {
        if (ImportedResource && ImportedResource->LODModels.IsValidIndex(LODLevel))
        {
            // Re-apply our clothing assets
            FLODUtilities::RestoreClothingFromBackup(SelectedSkelMesh, ClothingBindings, LODLevel);
        }
    };

    // don't import material and animation
    UnFbx::FBXImportOptions* ImportOptions = FFbxImporter->GetImportOptions();

    // Set the skeletal mesh import data from the base mesh, this make sure the import rotation transform is use when importing a LOD
    UFbxSkeletalMeshImportData* TempAssetImportData = NULL;

    UFbxAssetImportData* FbxAssetImportData         = Cast<UFbxAssetImportData>(SelectedSkelMesh->GetAssetImportData());
    if (FbxAssetImportData != nullptr)
    {
        UFbxSkeletalMeshImportData* ImportData = Cast<UFbxSkeletalMeshImportData>(FbxAssetImportData);
        if (ImportData)
        {
            TempAssetImportData = ImportData;
            UnFbx::FBXImportOptions::ResetOptions(ImportOptions);
            // Prepare the import options
            UFbxImportUI* ReimportUI     = NewObject<UFbxImportUI>();
            ReimportUI->MeshTypeToImport = FBXIT_SkeletalMesh;
            ReimportUI->Skeleton         = SelectedSkelMesh->GetSkeleton();
            ReimportUI->PhysicsAsset     = SelectedSkelMesh->GetPhysicsAsset();
            // Import data already exists, apply it to the fbx import options
            ReimportUI->SkeletalMeshImportData = ImportData;
            // Some options not supported with skeletal mesh
            ReimportUI->SkeletalMeshImportData->bBakePivotInVertex         = false;
            ReimportUI->SkeletalMeshImportData->bTransformVertexToAbsolute = true;
            ApplyImportUIToImportOptions(ReimportUI, *ImportOptions);
        }
        ImportOptions->bImportMaterials = false;
        ImportOptions->bImportTextures  = false;
    }
    ImportOptions->bImportAnimations = false;
    // Adjust the option in case we import only the skinning or the geometry
    if (ImportOptions->bImportAsSkeletalSkinning)
    {
        ImportOptions->bImportMaterials        = false;
        ImportOptions->bImportTextures         = false;
        ImportOptions->bImportLOD              = false;
        ImportOptions->bImportSkeletalMeshLODs = false;
        ImportOptions->bImportAnimations       = false;
        ImportOptions->bImportMorph            = false;
    }
    else if (ImportOptions->bImportAsSkeletalGeometry)
    {
        ImportOptions->bImportAnimations            = false;
        ImportOptions->bUpdateSkeletonReferencePose = false;
    }

    if (!FFbxImporter->ImportFromFile(*Filename, FPaths::GetExtension(Filename), true))
    {
        ReapplyClothing();
        // Log the error message and fail the import.
        FFbxImporter->AddTokenizedErrorMessage(FTokenizedMessage::Create(EMessageSeverity::Error, LOCTEXT("FBXImport_ParseFailed", "FBX file parsing failed.")), FFbxErrors::Generic_FBXFileParseFailed);
    }
    else
    {
        bool bUseLODs                = true;
        int32 MaxLODLevel            = 0;
        TArray<FbxNode*>* MeshObject = NULL;

        // Set the build options if the BuildDat is not available so it is the same option we use to import the LOD
        if (ImportedResource && ImportedResource->LODModels.IsValidIndex(LODLevel) && !SelectedSkelMesh->IsLODImportedDataBuildAvailable(LODLevel))
        {
            FSkeletalMeshLODInfo* LODInfo = SelectedSkelMesh->GetLODInfo(LODLevel);
            if (LODInfo)
            {
                LODInfo->BuildSettings.bBuildAdjacencyBuffer   = true;
                LODInfo->BuildSettings.bRecomputeNormals       = !ImportOptions->ShouldImportNormals();
                LODInfo->BuildSettings.bRecomputeTangents      = !ImportOptions->ShouldImportTangents();
                LODInfo->BuildSettings.bUseMikkTSpace          = (ImportOptions->NormalGenerationMethod == EFBXNormalGenerationMethod::MikkTSpace) && (!ImportOptions->ShouldImportNormals() || !ImportOptions->ShouldImportTangents());
                LODInfo->BuildSettings.bComputeWeightedNormals = ImportOptions->bComputeWeightedNormals;
                LODInfo->BuildSettings.bRemoveDegenerates      = ImportOptions->bRemoveDegenerates;
                LODInfo->BuildSettings.ThresholdPosition       = ImportOptions->OverlappingThresholds.ThresholdPosition;
                LODInfo->BuildSettings.ThresholdTangentNormal  = ImportOptions->OverlappingThresholds.ThresholdTangentNormal;
                LODInfo->BuildSettings.ThresholdUV             = ImportOptions->OverlappingThresholds.ThresholdUV;
                LODInfo->BuildSettings.MorphThresholdPosition  = ImportOptions->OverlappingThresholds.MorphThresholdPosition;
            }
        }

        // Populate the mesh array
        FFbxImporter->FillFbxSkelMeshArrayInScene(FFbxImporter->Scene->GetRootNode(), MeshArray, false, ImportOptions->bImportAsSkeletalGeometry || ImportOptions->bImportAsSkeletalSkinning, ImportOptions->bImportScene);

        // Nothing found, error out
        if (MeshArray.Num() == 0)
        {
            ReapplyClothing();
            FFbxImporter->AddTokenizedErrorMessage(FTokenizedMessage::Create(EMessageSeverity::Error, LOCTEXT("FBXImport_NoMesh", "No meshes were found in file.")), FFbxErrors::Generic_MeshNotFound);
            CleanUpScene();
            return false;
        }

        MeshObject = MeshArray[0];

        // check if there is LODGroup for this skeletal mesh
        for (int32 j = 0; j < MeshObject->Num(); j++)
        {
            FbxNode* Node = (*MeshObject)[j];
            if (Node->GetNodeAttribute() && Node->GetNodeAttribute()->GetAttributeType() == FbxNodeAttribute::eLODGroup)
            {
                // get max LODgroup level
                if (MaxLODLevel < (Node->GetChildCount() - 1))
                {
                    MaxLODLevel = Node->GetChildCount() - 1;
                }
            }
        }

        // No LODs found, switch to supporting a mesh array containing meshes instead of LODs
        if (MaxLODLevel == 0)
        {
            bUseLODs    = false;
            MaxLODLevel = SelectedSkelMesh->GetLODNum();
        }

        int32 SelectedLOD = LODLevel;
        if (SelectedLOD > SelectedSkelMesh->GetLODNum())
        {
            ReapplyClothing();
            // Make sure they don't manage to select a bad LOD index
            FFbxImporter->AddTokenizedErrorMessage(FTokenizedMessage::Create(EMessageSeverity::Warning, FText::Format(LOCTEXT("FBXImport_InvalidLODIdx", "Invalid mesh LOD index {0}, no prior LOD index exists"), FText::AsNumber(SelectedLOD))), FFbxErrors::Generic_Mesh_LOD_InvalidIndex);
        }
        else
        {
            TArray<FbxNode*> SkelMeshNodeArray;

            if (bUseLODs || ImportOptions->bImportMorph)
            {
                for (int32 j = 0; j < MeshObject->Num(); j++)
                {
                    FbxNode* Node = (*MeshObject)[j];
                    if (Node->GetNodeAttribute() && Node->GetNodeAttribute()->GetAttributeType() == FbxNodeAttribute::eLODGroup)
                    {
                        TArray<FbxNode*> NodeInLod;
                        if (Node->GetChildCount() > SelectedLOD)
                        {
                            FFbxImporter->FindAllLODGroupNode(NodeInLod, Node, SelectedLOD);
                        }
                        else  // in less some LODGroups have less level, use the last level
                        {
                            FFbxImporter->FindAllLODGroupNode(NodeInLod, Node, Node->GetChildCount() - 1);
                        }

                        for (FbxNode* MeshNode: NodeInLod)
                        {
                            SkelMeshNodeArray.Add(MeshNode);
                        }
                    }
                    else
                    {
                        SkelMeshNodeArray.Add(Node);
                    }
                }
            }

            // Import mesh
            USkeletalMesh* TempSkelMesh = NULL;
            TArray<FName> OrderedMaterialNames;
            {
                int32 NoneNameCount = 0;
                for (const FSkeletalMaterial& Material: SelectedSkelMesh->GetMaterials())
                {
                    if (Material.ImportedMaterialSlotName == NAME_None)
                        NoneNameCount++;

                    OrderedMaterialNames.Add(Material.ImportedMaterialSlotName);
                }
                if (NoneNameCount >= OrderedMaterialNames.Num())
                {
                    OrderedMaterialNames.Empty();
                }
            }

            TSharedPtr<FExistingSkelMeshData> SkelMeshDataPtr;
            if (SelectedSkelMesh->GetLODNum() > SelectedLOD)
            {
                SelectedSkelMesh->PreEditChange(NULL);
                SkelMeshDataPtr = SkeletalMeshImportUtils::SaveExistingSkelMeshData(SelectedSkelMesh, true, SelectedLOD);
            }

            // Original fbx data storage
            TArray<FName> ImportMaterialOriginalNameData;
            TArray<FImportMeshLodSectionsData> ImportMeshLodData;
            ImportMeshLodData.AddZeroed();
            FSkeletalMeshImportData OutData;

            UnFbx::FFbxImporter::FImportSkeletalMeshArgs ImportSkeletalMeshArgs;
            ImportSkeletalMeshArgs.InParent                       = SelectedSkelMesh->GetOutermost();
            ImportSkeletalMeshArgs.NodeArray                      = bUseLODs ? SkelMeshNodeArray : *MeshObject;
            ImportSkeletalMeshArgs.Name                           = NAME_None;
            ImportSkeletalMeshArgs.Flags                          = RF_Transient;
            ImportSkeletalMeshArgs.TemplateImportData             = TempAssetImportData;
            ImportSkeletalMeshArgs.LodIndex                       = SelectedLOD;
            ImportSkeletalMeshArgs.OrderedMaterialNames           = OrderedMaterialNames.Num() > 0 ? &OrderedMaterialNames : nullptr;
            ImportSkeletalMeshArgs.ImportMaterialOriginalNameData = &ImportMaterialOriginalNameData;
            ImportSkeletalMeshArgs.ImportMeshSectionsData         = &ImportMeshLodData[0];
            ImportSkeletalMeshArgs.OutData                        = &OutData;

            TempSkelMesh                                          = (USkeletalMesh*)FFbxImporter->ImportSkeletalMesh(ImportSkeletalMeshArgs);
            // Add the new imported LOD to the existing model (check skeleton compatibility)
            if (TempSkelMesh && FFbxImporter->ImportSkeletalMeshLOD(TempSkelMesh, SelectedSkelMesh, SelectedLOD, TempAssetImportData))
            {
                // Update the import data for this lod
                UnFbx::FFbxImporter::UpdateSkeletalMeshImportData(SelectedSkelMesh, nullptr, SelectedLOD, &ImportMaterialOriginalNameData, &ImportMeshLodData);

                if (SkelMeshDataPtr)
                {
                    SkeletalMeshImportUtils::RestoreExistingSkelMeshData(SkelMeshDataPtr, SelectedSkelMesh, SelectedLOD, false, ImportOptions->bImportAsSkeletalSkinning, ImportOptions->bResetToFbxOnMaterialConflict);
                }

                if (ImportOptions->bImportMorph)
                {
                    FFbxImporter->ImportFbxMorphTarget(SkelMeshNodeArray, SelectedSkelMesh, SelectedLOD, OutData);
                }

                bSuccess = true;

                // Set LOD source filename
                SelectedSkelMesh->GetLODInfo(SelectedLOD)->SourceImportFilename = UAssetImportData::SanitizeImportFilename(Filename, nullptr);
                SelectedSkelMesh->GetLODInfo(SelectedLOD)->bImportWithBaseMesh  = false;

                ReapplyClothing();

                // Must be the last step because it cleanup the fbx importer to import the alternate skinning FBX
                if (bMustReimportAlternateSkinWeightProfile)
                {
                    // We cannot use anymore the FFbxImporter after the cleanup
                    CleanUpScene();
                    FSkinWeightsUtilities::ReimportAlternateSkinWeight(SelectedSkelMesh, SelectedLOD);
                }

                // Notification of success
                FNotificationInfo NotificationInfo(FText::GetEmpty());
                NotificationInfo.Text           = FText::Format(NSLOCTEXT("UnrealEd", "LODImportSuccessful", "Mesh for LOD {0} imported successfully!"), FText::AsNumber(SelectedLOD));
                NotificationInfo.ExpireDuration = 5.0f;
                FSlateNotificationManager::Get().AddNotification(NotificationInfo);
            }
            else
            {
                ReapplyClothing();
                // Notification of failure
                FNotificationInfo NotificationInfo(FText::GetEmpty());
                NotificationInfo.Text           = FText::Format(NSLOCTEXT("UnrealEd", "LODImportFail", "Failed to import mesh for LOD {0}!"), FText::AsNumber(SelectedLOD));
                NotificationInfo.ExpireDuration = 5.0f;
                FSlateNotificationManager::Get().AddNotification(NotificationInfo);
            }
        }
    }
    CleanUpScene();
    return bSuccess;
}

FString PromptForLODImportFile(const FText& PromptTitle)
{
    FString ChosenFilname("");

    FString ExtensionStr;
    ExtensionStr += TEXT("All model files|*.fbx;*.obj|");
    ExtensionStr += TEXT("FBX files|*.fbx|");
    ExtensionStr += TEXT("Object files|*.obj|");
    ExtensionStr += TEXT("All files|*.*");

    // First, display the file open dialog for selecting the file.
    TArray<FString> OpenFilenames;
    IDesktopPlatform* DesktopPlatform = FDesktopPlatformModule::Get();
    bool bOpen                        = false;
    if (DesktopPlatform)
    {
        bOpen = DesktopPlatform->OpenFileDialog(
            FSlateApplication::Get().FindBestParentWindowHandleForDialogs(nullptr),
            PromptTitle.ToString(),
            *FEditorDirectories::Get().GetLastDirectory(ELastDirectory::FBX),
            TEXT(""),
            *ExtensionStr,
            EFileDialogFlags::None,
            OpenFilenames);
    }

    // Only continue if we pressed OK and have only one file selected.
    if (bOpen)
    {
        if (OpenFilenames.Num() == 0)
        {
            UnFbx::FFbxImporter* FFbxImporter = UnFbx::FFbxImporter::GetInstance();
            FFbxImporter->AddTokenizedErrorMessage(FTokenizedMessage::Create(EMessageSeverity::Error, LOCTEXT("NoFileSelectedForLOD", "No file was selected for the LOD.")), FFbxErrors::Generic_Mesh_LOD_NoFileSelected);
        }
        else if (OpenFilenames.Num() > 1)
        {
            UnFbx::FFbxImporter* FFbxImporter = UnFbx::FFbxImporter::GetInstance();
            FFbxImporter->AddTokenizedErrorMessage(FTokenizedMessage::Create(EMessageSeverity::Error, LOCTEXT("MultipleFilesSelectedForLOD", "You may only select one file for the LOD.")), FFbxErrors::Generic_Mesh_LOD_MultipleFilesSelected);
        }
        else
        {
            ChosenFilname = OpenFilenames[0];
            FEditorDirectories::Get().SetLastDirectory(ELastDirectory::FBX, FPaths::GetPath(ChosenFilname));  // Save path as default for next time.
        }
    }

    return ChosenFilname;
}

bool ImportMeshLODDialog(class UObject* SelectedMesh, int32 LODLevel, bool bNotifyCB /*= true*/)
{
    if (!SelectedMesh)
    {
        return false;
    }

    USkeletalMesh* SkeletalMesh = Cast<USkeletalMesh>(SelectedMesh);
    UStaticMesh* StaticMesh     = Cast<UStaticMesh>(SelectedMesh);

    if (!SkeletalMesh && !StaticMesh)
    {
        return false;
    }

    FString FilenameToImport("");

    if (SkeletalMesh)
    {
        if (SkeletalMesh->IsValidLODIndex(LODLevel))
        {
            FilenameToImport = SkeletalMesh->GetLODInfo(LODLevel)->SourceImportFilename.IsEmpty() ?
                                   SkeletalMesh->GetLODInfo(LODLevel)->SourceImportFilename :
                                   UAssetImportData::ResolveImportFilename(SkeletalMesh->GetLODInfo(LODLevel)->SourceImportFilename, nullptr);
        }
    }
    else if (StaticMesh)
    {
        if (StaticMesh->IsSourceModelValid(LODLevel))
        {
            const FStaticMeshSourceModel& SourceModel = StaticMesh->GetSourceModel(LODLevel);
            FilenameToImport                          = SourceModel.SourceImportFilename.IsEmpty() ?
                                                            SourceModel.SourceImportFilename :
                                                            UAssetImportData::ResolveImportFilename(SourceModel.SourceImportFilename, nullptr);
        }
    }

    // Check the file exists first
    const bool bSourceFileExists = FPaths::FileExists(FilenameToImport);
    // We'll give the user a chance to choose a new file if a previously set file fails to import
    const bool bPromptOnFail = bSourceFileExists;

    if (!bSourceFileExists || FilenameToImport.IsEmpty())
    {
        FText PromptTitle;

        if (FilenameToImport.IsEmpty())
        {
            PromptTitle = FText::Format(LOCTEXT("LODImportPrompt_NoSource", "Choose a file to import for LOD {0}"), FText::AsNumber(LODLevel));
        }
        else if (!bSourceFileExists)
        {
            PromptTitle = FText::Format(LOCTEXT("LODImportPrompt_SourceNotFound", "LOD {0} Source file not found. Choose new file."), FText::AsNumber(LODLevel));
        }

        FilenameToImport = PromptForLODImportFile(PromptTitle);
    }

    bool bImportSuccess = false;

    if (!FilenameToImport.IsEmpty())
    {
        if (SkeletalMesh)
        {
            bImportSuccess = ImportSkeletalMeshLOD(SkeletalMesh, FilenameToImport, LODLevel);
        }
        else if (StaticMesh)
        {
            bImportSuccess = ImportStaticMeshLOD(StaticMesh, FilenameToImport, LODLevel);
        }
    }

    if (!bImportSuccess && bPromptOnFail)
    {
        FMessageDialog::Open(EAppMsgType::Ok, FText::Format(LOCTEXT("LODImport_SourceMissingDialog", "Failed to import LOD{0} as the source file failed to import, please select a new source file."), FText::AsNumber(LODLevel)));

        FText PromptTitle = FText::Format(LOCTEXT("LODImportPrompt_SourceFailed", "Failed to import source file for LOD {0}, choose a new file"), FText::AsNumber(LODLevel));
        FilenameToImport  = PromptForLODImportFile(PromptTitle);

        if (FilenameToImport.Len() > 0 && FPaths::FileExists(FilenameToImport))
        {
            if (SkeletalMesh)
            {
                bImportSuccess = ImportSkeletalMeshLOD(SkeletalMesh, FilenameToImport, LODLevel);
            }
            else if (StaticMesh)
            {
                bImportSuccess = ImportStaticMeshLOD(StaticMesh, FilenameToImport, LODLevel);
            }
        }
    }

    // If the filename is empty it mean the user cancel the file selection
    if (!bImportSuccess && !FilenameToImport.IsEmpty())
    {
        // Failed to import a LOD, even after retries (if applicable)
        FMessageDialog::Open(EAppMsgType::Ok, FText::Format(LOCTEXT("LODImport_Failure", "Failed to import LOD{0}"), FText::AsNumber(LODLevel)));
    }

    if (bImportSuccess && bNotifyCB)
    {
        if (SkeletalMesh)
        {
            GEditor->GetEditorSubsystem<UImportSubsystem>()->BroadcastAssetPostLODImport(SkeletalMesh, LODLevel);
        }
        else if (StaticMesh)
        {
            GEditor->GetEditorSubsystem<UImportSubsystem>()->BroadcastAssetPostLODImport(StaticMesh, LODLevel);
        }
    }

    return bImportSuccess;
}

void SetImportOption(UFbxImportUI* ImportUI)
{
    UnFbx::FFbxImporter* FFbxImporter      = UnFbx::FFbxImporter::GetInstance();
    UnFbx::FBXImportOptions* ImportOptions = FFbxImporter->GetImportOptions();
    ApplyImportUIToImportOptions(ImportUI, *ImportOptions);
}
}  // namespace FbxMeshUtils

#undef LOCTEXT_NAMESPACE