bPreserveSmoothingGroups
bPreserveSmoothingGroups
#Overview
name: bPreserveSmoothingGroups
The value of this variable can be defined or overridden in .ini config files. 1 .ini config file referencing this setting variable.
It is referenced in 16 C++ source files.
#Summary
#Usage in the C++ source code
The purpose of bPreserveSmoothingGroups is to control the preservation of smoothing groups during the import of 3D meshes, particularly skeletal meshes, into Unreal Engine 5. This setting is primarily used in the mesh import system, specifically for skeletal meshes.
bPreserveSmoothingGroups is primarily used in the FBX import system, which is part of the UnrealEd module. It’s also referenced in the Interchange Editor plugin, which is likely an alternative import system.
The value of this variable is typically set during the import process, either through user interface options or programmatically when importing assets. It’s often initialized in constructor functions (e.g., UFbxSceneImportOptionsSkeletalMesh) and can be modified through various import settings dialogs.
This variable interacts with other import settings, such as bKeepSectionsSeparate, bUpdateSkeletonReferencePose, and bUseT0AsRefPose. It’s part of a larger set of import options that collectively determine how a mesh is processed during import.
Developers should be aware that when bPreserveSmoothingGroups is set to true, it can affect the geometry of the imported mesh. It causes the importer to physically split triangles with non-matching smoothing groups, which can increase the number of vertices in the mesh.
Best practices when using this variable include:
- Consider the desired visual outcome: Preserving smoothing groups can maintain the original mesh’s intended shading, but may increase vertex count.
- Be consistent across related assets: Use the same setting for all meshes in a set to ensure consistent appearance.
- Test both options: The impact can vary depending on the source mesh, so it’s worth testing both true and false settings to see which gives better results for your specific asset.
- Consider performance: If vertex count is a concern, setting this to false might be preferable, especially for mobile or VR projects where performance is critical.
- Use in conjunction with other import settings: Adjust related settings like bKeepSectionsSeparate to achieve the desired import result.
#Setting Variables
#References In INI files
Location: <Workspace>/Engine/Config/BaseEditorPerProjectUserSettings.ini:672, section: [/Script/UnrealEd.FbxSkeletalMeshImportData]
- INI Section:
/Script/UnrealEd.FbxSkeletalMeshImportData - Raw value:
True - Is Array:
False
#References in C++ code
#Callsites
This variable is referenced in the following C++ source code:
#Loc: <Workspace>/Engine/Plugins/Interchange/Editor/Source/InterchangeEditor/Private/InterchangeFbxAssetImportDataConverter.cpp:380
Scope (from outer to inner):
file
namespace UE::Interchange::Private
function UAssetImportData* ConvertToLegacyFbx
Source code excerpt:
DestinationSkeletalMeshImportData->bImportVertexAttributes = GenericAssetPipeline->MeshPipeline->bImportVertexAttributes;
DestinationSkeletalMeshImportData->bKeepSectionsSeparate = GenericAssetPipeline->CommonMeshesProperties->bKeepSectionsSeparate;
DestinationSkeletalMeshImportData->bPreserveSmoothingGroups = true;
DestinationSkeletalMeshImportData->bUpdateSkeletonReferencePose = GenericAssetPipeline->MeshPipeline->bUpdateSkeletonReferencePose;
DestinationSkeletalMeshImportData->bUseT0AsRefPose = GenericAssetPipeline->CommonSkeletalMeshesAndAnimationsProperties->bUseT0AsRefPose;
if (GenericAssetPipeline->MeshPipeline->SkeletalMeshImportContentType == EInterchangeSkeletalMeshContentType::All)
{
DestinationSkeletalMeshImportData->ImportContentType = EFBXImportContentType::FBXICT_All;
}
#Loc: <Workspace>/Engine/Plugins/Tests/EditorTests/Source/EditorTests/Private/UnrealEd/FbxAutomationTests.cpp:426
Scope (from outer to inner):
file
function BEGIN_FUNCTION_BUILD_OPTIMIZATION bool F
Source code excerpt:
ImportData->MorphThresholdPosition = TestPlan->ImportUI->SkeletalMeshImportData->MorphThresholdPosition;
ImportData->ThresholdUV = TestPlan->ImportUI->SkeletalMeshImportData->ThresholdUV;
ImportData->bPreserveSmoothingGroups = TestPlan->ImportUI->SkeletalMeshImportData->bPreserveSmoothingGroups;
ImportData->bKeepSectionsSeparate = TestPlan->ImportUI->SkeletalMeshImportData->bKeepSectionsSeparate;
ImportData->bUpdateSkeletonReferencePose = TestPlan->ImportUI->SkeletalMeshImportData->bUpdateSkeletonReferencePose;
ImportData->bUseT0AsRefPose = TestPlan->ImportUI->SkeletalMeshImportData->bUseT0AsRefPose;
//Copy UFbxMeshImportData
ImportData->bTransformVertexToAbsolute = TestPlan->ImportUI->SkeletalMeshImportData->bTransformVertexToAbsolute;
ImportData->bBakePivotInVertex = TestPlan->ImportUI->SkeletalMeshImportData->bBakePivotInVertex;
#Loc: <Workspace>/Engine/Plugins/Tests/EditorTests/Source/EditorTests/Private/UnrealEd/FbxAutomationTests.cpp:524
Scope (from outer to inner):
file
function BEGIN_FUNCTION_BUILD_OPTIMIZATION bool F
Source code excerpt:
ImportData->ThresholdUV = TestPlan->ImportUI->SkeletalMeshImportData->ThresholdUV;
ImportData->MorphThresholdPosition = TestPlan->ImportUI->SkeletalMeshImportData->MorphThresholdPosition;
ImportData->bPreserveSmoothingGroups = TestPlan->ImportUI->SkeletalMeshImportData->bPreserveSmoothingGroups;
ImportData->bKeepSectionsSeparate = TestPlan->ImportUI->SkeletalMeshImportData->bKeepSectionsSeparate;
ImportData->bUpdateSkeletonReferencePose = TestPlan->ImportUI->SkeletalMeshImportData->bUpdateSkeletonReferencePose;
ImportData->bUseT0AsRefPose = TestPlan->ImportUI->SkeletalMeshImportData->bUseT0AsRefPose;
//Copy UFbxMeshImportData
ImportData->bTransformVertexToAbsolute = TestPlan->ImportUI->SkeletalMeshImportData->bTransformVertexToAbsolute;
ImportData->bBakePivotInVertex = TestPlan->ImportUI->SkeletalMeshImportData->bBakePivotInVertex;
#Loc: <Workspace>/Engine/Source/Editor/UnrealEd/Classes/Factories/FbxSceneImportOptionsSkeletalMesh.h:32
Scope (from outer to inner):
file
class class UFbxSceneImportOptionsSkeletalMesh : public UObject
Source code excerpt:
/** If checked, triangles with non-matching smoothing groups will be physically split. */
UPROPERTY(EditAnywhere, config, Category = SkeletalMesh)
uint32 bPreserveSmoothingGroups : 1;
/** If checked, sections with matching materials are kept separate and will not get combined. */
UPROPERTY(EditAnywhere, config, Category = SkeletalMesh)
uint32 bKeepSectionsSeparate : 1;
/** If checked, meshes nested in bone hierarchies will be imported instead of being converted to bones. */
#Loc: <Workspace>/Engine/Source/Editor/UnrealEd/Classes/Factories/FbxSkeletalMeshImportData.h:74
Scope (from outer to inner):
file
class class UFbxSkeletalMeshImportData : public UFbxMeshImportData
Source code excerpt:
/** If checked, triangles with non-matching smoothing groups will be physically split. */
UPROPERTY(EditAnywhere, AdvancedDisplay, config, Category=Mesh, meta=(ImportType="SkeletalMesh|GeoOnly"))
uint32 bPreserveSmoothingGroups:1;
/** If checked, sections with matching materials are kept separate and will not get combined. */
UPROPERTY(EditAnywhere, AdvancedDisplay, config, Category=Mesh, meta=(ImportType="SkeletalMesh|GeoOnly"))
uint32 bKeepSectionsSeparate:1;
/** If checked, meshes nested in bone hierarchies will be imported instead of being converted to bones. */
#Loc: <Workspace>/Engine/Source/Editor/UnrealEd/Private/Fbx/FbxMainImport.cpp:476
Scope (from outer to inner):
file
namespace UnFbx
function void ApplyImportUIToImportOptions
Source code excerpt:
InOutImportOptions.bImportRigidMesh = ImportUI->OriginalImportType == FBXIT_StaticMesh && ImportUI->MeshTypeToImport == FBXIT_SkeletalMesh;
InOutImportOptions.bUseT0AsRefPose = ImportUI->SkeletalMeshImportData->bUseT0AsRefPose;
InOutImportOptions.bPreserveSmoothingGroups = ImportUI->SkeletalMeshImportData->bPreserveSmoothingGroups;
InOutImportOptions.bKeepSectionsSeparate = ImportUI->SkeletalMeshImportData->bKeepSectionsSeparate;
InOutImportOptions.OverlappingThresholds.ThresholdPosition = ImportUI->SkeletalMeshImportData->ThresholdPosition;
InOutImportOptions.OverlappingThresholds.ThresholdTangentNormal = ImportUI->SkeletalMeshImportData->ThresholdTangentNormal;
InOutImportOptions.OverlappingThresholds.ThresholdUV = ImportUI->SkeletalMeshImportData->ThresholdUV;
InOutImportOptions.OverlappingThresholds.MorphThresholdPosition = ImportUI->SkeletalMeshImportData->MorphThresholdPosition;
InOutImportOptions.bImportMeshesInBoneHierarchy = ImportUI->SkeletalMeshImportData->bImportMeshesInBoneHierarchy;
#Loc: <Workspace>/Engine/Source/Editor/UnrealEd/Private/Fbx/FbxMainImport.cpp:1760
Scope (from outer to inner):
file
lambda-function
Source code excerpt:
Attribs.Add(FAnalyticsEventAttribute(TEXT("SkeletalMeshOpt ImportMorph"), CaptureImportOptions->bImportMorph));
Attribs.Add(FAnalyticsEventAttribute(TEXT("SkeletalMeshOpt ImportSkeletalMeshLODs"), CaptureImportOptions->bImportSkeletalMeshLODs));
Attribs.Add(FAnalyticsEventAttribute(TEXT("SkeletalMeshOpt PreserveSmoothingGroups"), CaptureImportOptions->bPreserveSmoothingGroups));
Attribs.Add(FAnalyticsEventAttribute(TEXT("SkeletalMeshOpt KeepSectionsSeparate"), CaptureImportOptions->bKeepSectionsSeparate));
Attribs.Add(FAnalyticsEventAttribute(TEXT("SkeletalMeshOpt UpdateSkeletonReferencePose"), CaptureImportOptions->bUpdateSkeletonReferencePose));
Attribs.Add(FAnalyticsEventAttribute(TEXT("SkeletalMeshOpt UseT0AsRefPose"), CaptureImportOptions->bUseT0AsRefPose));
Attribs.Add(FAnalyticsEventAttribute(TEXT("SkeletalMeshOpt OverlappingThresholds.ThresholdPosition"), CaptureImportOptions->OverlappingThresholds.ThresholdPosition));
Attribs.Add(FAnalyticsEventAttribute(TEXT("SkeletalMeshOpt OverlappingThresholds.ThresholdTangentNormal"), CaptureImportOptions->OverlappingThresholds.ThresholdTangentNormal));
Attribs.Add(FAnalyticsEventAttribute(TEXT("SkeletalMeshOpt OverlappingThresholds.ThresholdUV"), CaptureImportOptions->OverlappingThresholds.ThresholdUV));
#Loc: <Workspace>/Engine/Source/Editor/UnrealEd/Private/Fbx/FbxSceneImportData.cpp:118
Scope (from outer to inner):
file
function UnFbx::FBXImportOptions *JSONToFbxOption
Source code excerpt:
//OptionObj->TryGetBoolField(TEXT("bUseT0AsRefPose"), Option->bUseT0AsRefPose);
Option->bUseT0AsRefPose = false;
OptionObj->TryGetBoolField(TEXT("bPreserveSmoothingGroups"), Option->bPreserveSmoothingGroups);
OptionObj->TryGetBoolField(TEXT("bKeepSectionsSeparate"), Option->bKeepSectionsSeparate);
OptionObj->TryGetBoolField(TEXT("bImportMeshesInBoneHierarchy"), Option->bImportMeshesInBoneHierarchy);
OptionObj->TryGetBoolField(TEXT("bImportMorphTargets"), Option->bImportMorph);
OptionObj->TryGetBoolField(TEXT("bImportVertexAttributes"), Option->bImportVertexAttributes);
if (OptionObj->TryGetObjectField(TEXT("OverlappingThresholds"), DataObj))
#Loc: <Workspace>/Engine/Source/Editor/UnrealEd/Private/Fbx/FbxSceneImportData.cpp:208
Scope (from outer to inner):
file
function FString FbxOptionToJSON
Source code excerpt:
Option->bUpdateSkeletonReferencePose ? 1 : 0,
Option->bUseT0AsRefPose ? 1 : 0,
Option->bPreserveSmoothingGroups ? 1 : 0,
Option->bKeepSectionsSeparate ? 1 : 0,
Option->bImportMeshesInBoneHierarchy ? 1 : 0,
Option->bImportMorph ? 1 : 0,
Option->bImportVertexAttributes ? 1 : 0,
Option->OverlappingThresholds.ThresholdPosition,
Option->OverlappingThresholds.ThresholdTangentNormal,
#Loc: <Workspace>/Engine/Source/Editor/UnrealEd/Private/Fbx/FbxSceneImportOptionsSkeletalMesh.cpp:15
Scope (from outer to inner):
file
function UFbxSceneImportOptionsSkeletalMesh::UFbxSceneImportOptionsSkeletalMesh
Source code excerpt:
, bCreatePhysicsAsset(false)
, bUseT0AsRefPose(false)
, bPreserveSmoothingGroups(false)
, bKeepSectionsSeparate(false)
, bImportMeshesInBoneHierarchy(true)
, bImportMorphTargets(false)
, bImportVertexAttributes(false)
, ThresholdPosition(THRESH_POINTS_ARE_SAME)
, ThresholdTangentNormal(THRESH_NORMALS_ARE_SAME)
#Loc: <Workspace>/Engine/Source/Editor/UnrealEd/Private/Fbx/FbxSceneImportOptionsSkeletalMesh.cpp:48
Scope (from outer to inner):
file
function void UFbxSceneImportOptionsSkeletalMesh::FillSkeletalMeshInmportData
Source code excerpt:
SkeletalMeshImportData->ThresholdUV = ThresholdUV;
SkeletalMeshImportData->MorphThresholdPosition = MorphThresholdPosition;
SkeletalMeshImportData->bPreserveSmoothingGroups = bPreserveSmoothingGroups;
SkeletalMeshImportData->bKeepSectionsSeparate = bKeepSectionsSeparate;
SkeletalMeshImportData->bUpdateSkeletonReferencePose = bUpdateSkeletonReferencePose;
SkeletalMeshImportData->bUseT0AsRefPose = bUseT0AsRefPose;
SkeletalMeshImportData->bImportMeshLODs = SceneImportOptions->bImportSkeletalMeshLODs;
SkeletalMeshImportData->ImportTranslation = SceneImportOptions->ImportTranslation;
#Loc: <Workspace>/Engine/Source/Editor/UnrealEd/Private/Fbx/FbxSkeletalMeshImport.cpp:1451
Scope (from outer to inner):
file
function bool UnFbx::FFbxImporter::FillSkeletalMeshImportData
Source code excerpt:
}
if (ImportOptions->bPreserveSmoothingGroups)
{
bool bDuplicateUnSmoothWedges = false; //We deprecate legacy build
DoUnSmoothVerts(*SkelMeshImportDataPtr, bDuplicateUnSmoothWedges);
}
else
{
#Loc: <Workspace>/Engine/Source/Editor/UnrealEd/Private/Fbx/FbxSkeletalMeshImport.cpp:3271
Scope (from outer to inner):
file
function bool UnFbx::FFbxImporter::FillSkelMeshImporterFromFbx
Source code excerpt:
}
if( LayerCount > 0 && ImportOptions->bPreserveSmoothingGroups )
{
// Check and see if the smooothing data is valid. If not generate it from the normals
BaseLayer = Mesh->GetLayer(0);
if( BaseLayer )
{
const FbxLayerElementSmoothing* SmoothingLayer = BaseLayer->GetSmoothing();
#Loc: <Workspace>/Engine/Source/Editor/UnrealEd/Private/Fbx/SFbxSceneOptionWindow.cpp:1501
Scope (from outer to inner):
file
function void SFbxSceneOptionWindow::CopySkeletalMeshOptionsToFbxOptions
Source code excerpt:
ImportSettings->OverlappingThresholds.ThresholdUV = SkeletalMeshOptions->ThresholdUV;
ImportSettings->OverlappingThresholds.MorphThresholdPosition = SkeletalMeshOptions->MorphThresholdPosition;
ImportSettings->bPreserveSmoothingGroups = SkeletalMeshOptions->bPreserveSmoothingGroups;
ImportSettings->bKeepSectionsSeparate = SkeletalMeshOptions->bKeepSectionsSeparate;
ImportSettings->bUpdateSkeletonReferencePose = SkeletalMeshOptions->bUpdateSkeletonReferencePose;
ImportSettings->bUseT0AsRefPose = SkeletalMeshOptions->bUseT0AsRefPose;
ImportSettings->bImportAnimations = SkeletalMeshOptions->bImportAnimations;
ImportSettings->AnimationLengthImportType = SkeletalMeshOptions->AnimationLength;
#Loc: <Workspace>/Engine/Source/Editor/UnrealEd/Private/Fbx/SFbxSceneOptionWindow.cpp:1530
Scope (from outer to inner):
file
function void SFbxSceneOptionWindow::CopyFbxOptionsToSkeletalMeshOptions
Source code excerpt:
SkeletalMeshOptions->ThresholdUV = ImportSettings->OverlappingThresholds.ThresholdUV;
SkeletalMeshOptions->MorphThresholdPosition = ImportSettings->OverlappingThresholds.MorphThresholdPosition;
SkeletalMeshOptions->bPreserveSmoothingGroups = ImportSettings->bPreserveSmoothingGroups;
SkeletalMeshOptions->bKeepSectionsSeparate = ImportSettings->bKeepSectionsSeparate;
SkeletalMeshOptions->bUpdateSkeletonReferencePose = ImportSettings->bUpdateSkeletonReferencePose;
SkeletalMeshOptions->bUseT0AsRefPose = ImportSettings->bUseT0AsRefPose;
SkeletalMeshOptions->bImportAnimations = ImportSettings->bImportAnimations;
SkeletalMeshOptions->AnimationLength = ImportSettings->AnimationLengthImportType;
#Loc: <Workspace>/Engine/Source/Editor/UnrealEd/Public/FbxImporter.h:183
Scope (from outer to inner):
file
namespace UnFbx
Source code excerpt:
bool bImportRigidMesh;
bool bUseT0AsRefPose;
bool bPreserveSmoothingGroups;
bool bKeepSectionsSeparate;
FOverlappingThresholds OverlappingThresholds;
bool bImportMeshesInBoneHierarchy;
bool bCreatePhysicsAsset;
UPhysicsAsset *PhysicsAsset;
bool bImportSkeletalMeshLODs;