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  3. FMeshPlaneCut

FMeshPlaneCut

Cut the Mesh with the Plane.

API > API/Plugins > API/Plugins/DynamicMesh

Cut the Mesh with the Plane. The positive side, ie (p-o).n > 0, is removed. If possible, returns boundary loop(s) along cut (this will fail if cut intersected with holes in mesh). Also FillHoles() for a topological fill. Or use CutLoops and fill yourself.

Algorithm is: 1) find all edge crossings 2) optionally discard any triangles with all vertex distances < epsilon. 3) Do edge splits at crossings 4 option a) (optionally) delete all vertices on positive side 4 option b) (OR optionally) disconnect all triangles w/ vertices on positive side (if keeping both sides) 4 option c) do nothing (if keeping both sides and not disconnecting them) 5) (optionally) collapse any degenerate boundary edges 6) (optionally) change an attribute tag for all triangles on positive side 7) find loops through valid boundary edges (ie connected to splits, or on-plane edges) (if second half was kept, do this separately for each separate mesh ID label)

   
Name FMeshPlaneCut
Type class
Header File /Engine/Plugins/Runtime/GeometryProcessing/Source/DynamicMesh/Public/Operations/MeshPlaneCut.h
Include Path #include "Operations/MeshPlaneCut.h"

Syntax

class FMeshPlaneCut : public UE::Geometry::FMeshPlaneCutFixLayout

Inheritance Hierarchy

Constructors

Name Remarks Include Path Unreal Specifiers

FMeshPlaneCut ( FDynamicMesh3* Mesh,
FVector3d Origin,
FVector3d Normal
)

 Cut mesh with plane. Assumption is that plane normal is Z value. Operations/MeshPlaneCut.h  

Destructors

Name Remarks Include Path Unreal Specifiers

virtual PRAGMA_DISABLE_DEPRECATION_WARNINGS ~FMeshPlaneCut()

 Note: deprecation warnings disabled on destructor due to deprecated member variables. Operations/MeshPlaneCut.h  

Structs

Name Remarks
FCutResultRegion  
FOpenBoundary TODO support optionally restricting plane cut to a mesh selection MeshFaceSelection CutFaceSet; Outputs

Variables

Public

Name Type Remarks Include Path Unreal Specifiers
bCollapseDegenerateEdgesOnCut bool   Operations/MeshPlaneCut.h  
bSimplifyAlongNewEdges bool Control whether we attempt to auto-simplify the small planar triangles that the plane cut operation tends to generate Operations/MeshPlaneCut.h  
DegenerateEdgeTol double   Operations/MeshPlaneCut.h  
EdgeFilterFunc TUniqueFunction< bool(int32)> If set, only edges that pass this filter will be split Operations/MeshPlaneCut.h  
HoleFillTriangles TArray< TArray< int > > Triangle IDs of hole fill triangles. Outer array is 1:1 with the OpenBoundaries array. Operations/MeshPlaneCut.h  
Mesh FDynamicMesh3 * Inputs Operations/MeshPlaneCut.h  
OpenBoundaries TArray< FOpenBoundary > Note: loops and spans within a single FOpenBoundary could be part of the same hole-fill triangulation separate open boundary structs will be considered separately and will not share hole fill triangles Operations/MeshPlaneCut.h  
PlaneNormal FVector3d   Operations/MeshPlaneCut.h  
PlaneOrigin FVector3d   Operations/MeshPlaneCut.h  
PlaneTolerance double Tolerance distance for considering a vertex to be 'on plane' Operations/MeshPlaneCut.h  
ResultRegions TArray< FCutResultRegion > List of output cut regions (eg that have separate GroupIDs). Operations/MeshPlaneCut.h  
ResultSeedTriangles PRAGMA_DISABLE_DEPRECATION_WARNINGSTArray< int32 > List of output cut triangles representing the seed triangles along the cut. Operations/MeshPlaneCut.h  
SimplifySettings FLocalPlanarSimplify Settings to apply if bSimplifyAlongNewEdges == true Operations/MeshPlaneCut.h  
UVScaleFactor float UVs on any hole fill surfaces are scaled by this amount Operations/MeshPlaneCut.h  

Functions

Public

Name Remarks Include Path Unreal Specifiers

virtual bool Cut()

 Compute the plane cut by splitting mesh edges that cross the cut plane, and then deleting any triangles on the positive side of the cutting plane. Operations/MeshPlaneCut.h  

virtual bool CutWithoutDelete ( bool bSplitVerticesAtPlane,
float OffsetSeparatedPortion,
TDynamicMeshScalarTriangleAttribute< int >* TriLabels,
int NewLabelStartID,
bool bAddBoundariesFirstHalf,
bool bAddBoundariesSecondHalf
)

 Compute the plane cut by splitting mesh edges that cross the cut plane, but not deleting triangles on positive side. Operations/MeshPlaneCut.h  

virtual bool HoleFill ( TFunction< TArray< FIndex3i >(const FGeneralPolygon2d&)> PlanarTriangulationFunc,
bool bFillSpans,
int ConstantGroupID,
int MaterialID
)

 Fill cut loops with FPlanarHoleFiller, using a caller-provided triangulation function Operations/MeshPlaneCut.h  

virtual bool MinimalHoleFill ( int ConstantGroupID
)

   Operations/MeshPlaneCut.h  

virtual bool SimpleHoleFill ( int ConstantGroupID
)

 Fill cut loops with FSimpleHoleFiller Operations/MeshPlaneCut.h  

virtual bool SplitEdgesOnly ( bool bAssignNewGroups,
TSet< int32 >* OptionalTriangleSelection
)

 Compute the plane cut by splitting mesh edges that cross the cut plane, and then optionally update groups Operations/MeshPlaneCut.h  

virtual bool SplitEdgesOnly ( bool bAssignNewGroups
)

   Operations/MeshPlaneCut.h  

virtual void TransferTriangleLabelsToHoleFillTriangles ( TDynamicMeshScalarTriangleAttribute< int >* TriLabels
)

   Operations/MeshPlaneCut.h  

virtual EOperationValidationResult Validate()

   Operations/MeshPlaneCut.h  

Protected

Name Remarks Include Path Unreal Specifiers

void CollapseDegenerateEdges ( const TSet< int >& OnCutEdges,
const TSet< int >& ZeroEdges
)

   Operations/MeshPlaneCut.h  

void CollapseDegenerateEdges ( TSet< int >& Edges,
bool bRemoveAllDegenerateFromInputSet,
TSet< int >* TriangleSelection
)

 Collapse degenerate edges Operations/MeshPlaneCut.h  

bool ExtractBoundaryLoops ( const TSet< int >& OnCutEdges,
const TSet< int >& ZeroEdges,
FMeshPlaneCut::FOpenBoundary& Boundary
)

   Operations/MeshPlaneCut.h  

void SplitCrossingEdges ( bool bDeleteTrisOnPlane,
TArray< double >& Signs,
TSet< int >& AlreadyOnPlaneEdges,
TSet< int32 >& CutPlaneEdges,
TSet< int >* SplitEdges,
TSet< int >* OnPlaneVertices,
TSet< int >* TriangleSelection
)

   Operations/MeshPlaneCut.h  

void SplitCrossingEdges ( TArray< double >& Signs,
TSet< int >& ZeroEdges,
TSet< int >& OnCutEdges,
TSet< int >& OnSplitEdges,
bool bDeleteTrisOnPlane
)

   Operations/MeshPlaneCut.h  

void SplitCrossingEdges ( TArray< double >& Signs,
TSet< int >& ZeroEdges,
TSet< int >& OnCutEdges,
bool bDeleteTrisOnPlane
)

   Operations/MeshPlaneCut.h  

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