UE::Geometry::FMeshBoolean Class Reference

#include <MeshBoolean.h>

Classes
struct	FCustomInsideMeshTest
struct	FCustomInsideTestContext

Public Types
enum class	EBooleanOp {   Union , Difference , Intersect , TrimInside ,   TrimOutside , NewGroupInside , NewGroupOutside }
using	TestInsideFunctionType = TFunction< bool(const FVector3d &TestPosition, const FCustomInsideTestContext &Context)>

Public Member Functions
	FMeshBoolean (const FDynamicMesh3 *MeshA, const FTransformSRT3d &TransformA, const FDynamicMesh3 *MeshB, const FTransformSRT3d &TransformB, FDynamicMesh3 *OutputMesh, EBooleanOp Operation)
	FMeshBoolean (const FDynamicMesh3 *MeshA, const FDynamicMesh3 *MeshB, FDynamicMesh3 *OutputMesh, EBooleanOp Operation)
virtual	~FMeshBoolean ()
EOperationValidationResult	Validate ()
GEOMETRYCORE_API bool	Compute ()
GEOMETRYCORE_API bool	ComputeWithCustomInside (FCustomInsideMeshTest TestMeshA, FCustomInsideMeshTest TestMeshB)

Public Attributes
const FDynamicMesh3 *	Meshes [2]
const FTransformSRT3d	Transforms [2]
EBooleanOp	Operation
double	SnapTolerance = FMathf::ZeroTolerance * 1.0
bool	bCollapseDegenerateEdgesOnCut = true
double	DegenerateEdgeTolFactor = 1.5
double	WindingThreshold = .5
bool	bPutResultInInputSpace = true
bool	bWeldSharedEdges = true
bool	bTrackAllNewEdges = false
FProgressCancel *	Progress = nullptr
bool	bSimplifyAlongNewEdges = false
double	SimplificationAngleTolerance = .1
double	TryToImproveTriQualityThreshold = .5
bool	bPreserveTriangleGroups = true
bool	bPreserveVertexUVs = true
bool	bPreserveOverlayUVs = true
float	UVDistortTolerance = FMathf::ZeroTolerance
bool	bPreserveVertexNormals = true
float	NormalDistortTolerance = .01f
int	PreserveUVsOnlyForMesh = -1
FDynamicMesh3 *	Result
FTransformSRT3d	ResultTransform
TArray< int >	CreatedBoundaryEdges
TSet< int32 >	AllNewEdges
bool	bPopulateSecondMeshGroupMap = false
FIndexMapi	SecondMeshGroupMap
TOptional< TArray< int8 > >	TrackPerTriangleSourceMesh

Protected Member Functions
virtual bool	Cancelled ()

Detailed Description

MeshBoolean – perform a boolean operation on two input meshes.

Member Typedef Documentation

TestInsideFunctionType

using UE::Geometry::FMeshBoolean::TestInsideFunctionType = TFunction<bool(const FVector3d& TestPosition, const FCustomInsideTestContext& Context)>

Member Enumeration Documentation

EBooleanOp

enum class UE::Geometry::FMeshBoolean::EBooleanOp

strong

Enumerator
Union
Difference
Intersect
TrimInside
TrimOutside
NewGroupInside
NewGroupOutside

Constructor & Destructor Documentation

FMeshBoolean() [1/2]

UE::Geometry::FMeshBoolean::FMeshBoolean ( const FDynamicMesh3 *  MeshA, const FTransformSRT3d &  TransformA, const FDynamicMesh3 *  MeshB, const FTransformSRT3d &  TransformB, FDynamicMesh3 *  OutputMesh, EBooleanOp  Operation  )

inline

Perform a boolean operation to combine two meshes into a provided output mesh.

Parameters

MeshA	First mesh to combine
TransformA	Transform of MeshA
MeshB	Second mesh to combine
TransformB	Transform of MeshB
OutputMesh	Mesh to store output
Operation	How to combine meshes

FMeshBoolean() [2/2]

UE::Geometry::FMeshBoolean::FMeshBoolean ( const FDynamicMesh3 *  MeshA, const FDynamicMesh3 *  MeshB, FDynamicMesh3 *  OutputMesh, EBooleanOp  Operation  )

inline

~FMeshBoolean()

virtual UE::Geometry::FMeshBoolean::~FMeshBoolean ( )

inlinevirtual

Member Function Documentation

Cancelled()

virtual bool UE::Geometry::FMeshBoolean::Cancelled ( )

inlineprotectedvirtual

If this returns true, abort computation.

Compute()

bool FMeshBoolean::Compute

(

)

Compute the Boolean operation, using winding number for inside/outside tests

Returns

true if operation succeeds

ComputeWithCustomInside()

bool FMeshBoolean::ComputeWithCustomInside	(	FCustomInsideMeshTest	TestMeshA,
		FCustomInsideMeshTest	TestMeshB
	)

Compute the Boolean operation with a custom function determining if points are inside the given mesh

Validate()

EOperationValidationResult UE::Geometry::FMeshBoolean::Validate ( )

inline

Returns

EOperationValidationResult::Ok if we can apply operation, or error code if we cannot

Member Data Documentation

AllNewEdges

TSet<int32> UE::Geometry::FMeshBoolean::AllNewEdges

All edges created by mesh boolean algorithm. Only populated if bTrackAllNewEdges = true

bCollapseDegenerateEdgesOnCut

bool UE::Geometry::FMeshBoolean::bCollapseDegenerateEdgesOnCut = true

Whether to do additional processing to try to remove degenerate edges

bPopulateSecondMeshGroupMap

bool UE::Geometry::FMeshBoolean::bPopulateSecondMeshGroupMap = false

When doing an operation that merges two meshes (Union, Difference, Intersect) and bPopulateSecondMeshGroupMap is true, we populate a map from group ID's in the second mesh to group ID's in the result. Useful when the boolean is part of another operation that might want to track selection into the result.

TODO: It would be nice to have a similar triangle map, but it's more tedious to implement due to the mesh cuts that happen. We might also someday want something similar for the first mesh, where the group ID's will usually stay the same except when all triangles of a particular group are removed and the group ID is repurposed for the second mesh...

bPreserveOverlayUVs

bool UE::Geometry::FMeshBoolean::bPreserveOverlayUVs = true

Prevent simplification from distorting overlay UVs

bPreserveTriangleGroups

bool UE::Geometry::FMeshBoolean::bPreserveTriangleGroups = true

Prevent simplification from distorting triangle groups

bPreserveVertexNormals

bool UE::Geometry::FMeshBoolean::bPreserveVertexNormals = true

Prevent simplification from distorting vertex normals

bPreserveVertexUVs

bool UE::Geometry::FMeshBoolean::bPreserveVertexUVs = true

Prevent simplification from distorting vertex UVs

bPutResultInInputSpace

bool UE::Geometry::FMeshBoolean::bPutResultInInputSpace = true

Put the Result mesh in the same space as the input. If true, ResultTransform will be the identity transform.

bSimplifyAlongNewEdges

bool UE::Geometry::FMeshBoolean::bSimplifyAlongNewEdges = false

Control whether we attempt to auto-simplify the small planar triangles that the boolean operation tends to generate

bTrackAllNewEdges

bool UE::Geometry::FMeshBoolean::bTrackAllNewEdges = false

Control whether new edges should be tracked

bWeldSharedEdges

bool UE::Geometry::FMeshBoolean::bWeldSharedEdges = true

Weld newly-created cut edges where the input meshes meet. If false, the input meshes will remain topologically disconnected.

CreatedBoundaryEdges

TArray<int> UE::Geometry::FMeshBoolean::CreatedBoundaryEdges

Boundary edges created by the mesh boolean algorithm failing to cleanly weld (doesn't include boundaries that already existed in source meshes)

DegenerateEdgeTolFactor

double UE::Geometry::FMeshBoolean::DegenerateEdgeTolFactor = 1.5

Tolerance factor (multiplied by SnapTolerance) for removing short edges created by the cutting process; should be no more than 2

Meshes

const FDynamicMesh3* UE::Geometry::FMeshBoolean::Meshes[2]

NormalDistortTolerance

float UE::Geometry::FMeshBoolean::NormalDistortTolerance = .01f

When preserving normals, sets maximum allowed change in normals from collapsing an edge, measured at the removed vertex in degrees

Operation

EBooleanOp UE::Geometry::FMeshBoolean::Operation

PreserveUVsOnlyForMesh

int UE::Geometry::FMeshBoolean::PreserveUVsOnlyForMesh = -1

If > -1, then only preserve the UVs of one of the input meshes. Useful when cutting an artist-created asset w/ procedural geometry.

Progress

FProgressCancel* UE::Geometry::FMeshBoolean::Progress = nullptr

Set this to be able to cancel running operation

Result

FDynamicMesh3* UE::Geometry::FMeshBoolean::Result

ResultTransform

FTransformSRT3d UE::Geometry::FMeshBoolean::ResultTransform

Transform taking the result mesh back to the original space of the inputs

SecondMeshGroupMap

FIndexMapi UE::Geometry::FMeshBoolean::SecondMeshGroupMap

SimplificationAngleTolerance

double UE::Geometry::FMeshBoolean::SimplificationAngleTolerance = .1

Degrees of deviation from coplanar that we will still simplify

SnapTolerance

double UE::Geometry::FMeshBoolean::SnapTolerance = FMathf::ZeroTolerance * 1.0

Tolerance distance for considering a point to be on a vertex or edge, especially during mesh-mesh cutting

TrackPerTriangleSourceMesh

TOptional<TArray<int8> > UE::Geometry::FMeshBoolean::TrackPerTriangleSourceMesh

Transforms

const FTransformSRT3d UE::Geometry::FMeshBoolean::Transforms[2]

TryToImproveTriQualityThreshold

double UE::Geometry::FMeshBoolean::TryToImproveTriQualityThreshold = .5

If triangle quality (aspect ratio) is worse than this threshold, only simplify in ways that improve quality. If <= 0, triangle quality is ignored. Note: For aspect ratio we use definition: 4*TriArea / (sqrt(3)*MaxEdgeLen^2), ref: https://people.eecs.berkeley.edu/~jrs/papers/elemj.pdf p.53 Equilateral triangles have value 1; Smaller values -> lower quality

UVDistortTolerance

float UE::Geometry::FMeshBoolean::UVDistortTolerance = FMathf::ZeroTolerance

When preserving UVs, sets maximum allowed change in UV coordinates from collapsing an edge, measured at the removed vertex

WindingThreshold

double UE::Geometry::FMeshBoolean::WindingThreshold = .5

Threshold to determine whether triangle in one mesh is inside or outside of the other

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The documentation for this class was generated from the following files:

• Engine/Source/Runtime/GeometryCore/Public/Operations/MeshBoolean.h
• Engine/Source/Runtime/GeometryCore/Private/Operations/MeshBoolean.cpp