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  3. FLocalPlanarSimplify

FLocalPlanarSimplify

Class to support local planar simplification, to reduce excess edges created by plane cuts, edge loop insertions, and similar operations (Note a custom version of this logic also exists on the [FMeshBoolean](API\Runtime\GeometryCore\FMeshBoolean) class)

API > API/Runtime > API/Runtime/GeometryCore

Class to support local planar simplification, to reduce excess edges created by plane cuts, edge loop insertions, and similar operations (Note a custom version of this logic also exists on the FMeshBoolean class)

   
Name FLocalPlanarSimplify
Type class
Header File /Engine/Source/Runtime/GeometryCore/Public/Operations/LocalPlanarSimplify.h
Include Path #include "Operations/LocalPlanarSimplify.h"

Syntax

class FLocalPlanarSimplify

Variables

Public

Name Type Remarks Include Path Unreal Specifiers
bPreserveOverlayUVs bool Prevent simplification from distorting overlay UVs Operations/LocalPlanarSimplify.h  
bPreserveTriangleGroups bool Prevent simplification from distorting triangle groups Operations/LocalPlanarSimplify.h  
bPreserveVertexNormals bool Prevent simplification from distorting vertex normals Operations/LocalPlanarSimplify.h  
bPreserveVertexUVs bool Prevent simplification from distorting vertex UVs Operations/LocalPlanarSimplify.h  
NormalDistortTolerance float When preserving normals, sets maximum allowed change in normals from collapsing an edge, measured at the removed vertex in degrees Operations/LocalPlanarSimplify.h  
SimplificationAngleTolerance double Degrees of deviation from coplanar that we will still simplify Operations/LocalPlanarSimplify.h  
TryToImproveTriQualityThreshold double If triangle quality (aspect ratio) is worse than this threshold, only simplify in ways that improve quality. Operations/LocalPlanarSimplify.h  
UVDistortTolerance float When preserving UVs, sets maximum allowed change in UV coordinates from collapsing an edge, measured at the removed vertex Operations/LocalPlanarSimplify.h  

Functions

Public

Name Remarks Include Path Unreal Specifiers

void SimplifyAlongEdges ( FDynamicMesh3& Mesh,
TSet< int32 >& InOutEdges,
TUniqueFunction< void(const DynamicMeshInfo::FEdgeCollapseInfo&)> ProcessCollapse
) const

 Simplify Mesh along the given edges, and update the edge set accordingly Operations/LocalPlanarSimplify.h  

Static

Name Remarks Include Path Unreal Specifiers

static void CollapseDegenerateEdges ( FDynamicMesh3& Mesh,
TSet< int32 >& InOutEdges,
bool bRemoveAllDegenerateFromInputSet,
double DegenerateEdgeLenTol,
TSet< int >* TriangleSelection
)

 Collapse degenerate edges. Operations/LocalPlanarSimplify.h  

static bool CollapseWouldChangeShapeOrUVs ( const FDynamicMesh3& Mesh,
const TSet< int >& PathEdgeSet,
double DotTolerance,
int SourceEID,
int32 RemoveV,
const FVector3d& RemoveVPos,
int32 KeepV,
const FVector3d& KeepVPos,
const FVector3d& EdgeDir,
bool bPreserveTriangleGroups,
bool bPreserveUVsForMesh,
bool bPreserveVertexUVs,
bool bPreserveOverlayUVs,
float UVToleranceSq,
bool bPreserveVertexNormals,
float NormalEqualCosThreshold
)

 Test if a given edge collapse would change the mesh shape, mesh triangle group shape, or UVs unacceptably Operations/LocalPlanarSimplify.h  

static bool CollapseWouldHurtTriangleQuality ( const FDynamicMesh3& Mesh,
const FVector3d& RemoveVNormal,
int32 RemoveV,
const FVector3d& RemoveVPos,
int32 KeepV,
const FVector3d& KeepVPos,
double TryToImproveTriQualityThreshold,
bool bHasMultipleNormals
)

 Test if a given edge collapse would cause a triangle flip or other unacceptable decrease in mesh quality Specialized for collapsing at flat triangles Test if a given edge collapse would cause a triangle flip or other unacceptable decrease in mesh quality Operations/LocalPlanarSimplify.h  

static bool IsDevelopableAlongEdge ( const FDynamicMesh3& Mesh,
int EID,
int VID,
double DotTolerance,
FVector3d& NormalA,
bool& bIsFlat
)

 Test if the triangles connected to a vertex could be flattened by folding along the given edge Operations/LocalPlanarSimplify.h  

static bool IsFlat ( const FDynamicMesh3& Mesh,
int VID,
double DotTolerance,
FVector3d& OutFirstNormal
)

 The below helper functions are used by SimplifyAlongEdges, but also the similar customized versions of the same algorithm in FMeshBoolean and FMeshSelfUnion as well Test if the triangles connected to a vertex are all coplanar Operations/LocalPlanarSimplify.h  

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