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  3. FDelaunay2

FDelaunay2

API > API/Runtime > API/Runtime/GeometryCore > API/Runtime/GeometryCore/CompGeom

References

   
Module GeometryCore
Header /Engine/Source/Runtime/GeometryCore/Public/CompGeom/Delaunay2.h
Include #include "CompGeom/Delaunay2.h"

Syntax

class FDelaunay2

Variables

  Type Name Description
Public variable bool bAutomaticallyFixEdgesToDuplicateVertices Option to automatically track duplicate vertices and treat edges that reference them as if they referenced the instance that was actually used in the triangulation Note: Cannot change this to 'true' after triangulation and then call ConstrainEdges; duplicate vertices will only be detected on their initial insertion
Protected variable bool bIsConstrained  
Public variable bool bKeepFastEdgeAdjacencyData Option to keep extra vertex->edge adjacency data; useful if you will call ConstrainEdges many times on the same triangulation.
Public variable bool bValidateEdges Option to validate that edges remain in the triangulation after multiple constraint edges passed in Only validates for the edges in the current call; if separate calls constrain additional edges, set this to 'false' and call HasEdges() on the full edge set TODO: Consider having the internal mesh remember what edges have been constrained, so we can set an error flag when constrained edges cross previous constrained edges
Protected variable TPimplPtr< FDelaunay2Connectivity > Connectivity  
Public variable FRandomStream RandomStream Source for random permutations, used internally in the triangulation algorithm.

Functions

  Type Name Description
Public function Static TArray< TArray< TVector2< RealType > > >

ComputeVoronoiCells ( TArrayView< const TVector2< RealType >> Sites,
bool bIncludeBoundary,
TAxisAlignedBox2< RealType > ClipBounds,
RealType ExpandBounds
)

 Compute Voronoi diagram cells
Public function bool

ConstrainEdges ( TArrayView< const TVector2< float >> Vertices,
TArrayView< const FIndex2i > Edges
)

 Update an already-computed triangulation so the given edges are in the triangulation.
Public function bool

ConstrainEdges ( TArrayView< const TVector2< double >> Vertices,
TArrayView< const FIndex2i > Edges
)

 Update an already-computed triangulation so the given edges are in the triangulation.
Public function void Remap any references to duplicate vertices to only reference the vertices used in the triangulation.
Public function Const bool

GetFilledTriangles ( TArray< FIndex3i >& TrianglesOut,
TArrayView< const FIndex2i > BoundaryEdges,
TArrayView< const FIndex2i > HoleEdges
)

 Get (by reference) the triangles that are inside the given edges, removing the outside-boundary triangles and the inside-hole triangles
Public function Const bool

GetFilledTriangles ( TArray< FIndex3i >& TrianglesOut,
TArrayView< const FIndex2i > Edges,
EFillMode FillMode
)

 Get (by reference) the triangles that are inside the given edges, removing the outer boundary triangles If a Winding-Number-based fill mode is used, assumes edges are oriented and tracks the winding number across edges
Public function TArray< FIndex3i >

GetFilledTriangles ( TArrayView< const FIndex2i > Edges,
EFillMode FillMode
)

 Return the triangles that are inside the given edges, removing the outer boundary triangles If a Winding-Number-based fill mode is used, assumes edges are oriented and tracks the winding number across edges
Public function Const bool

GetFilledTrianglesGeneralizedWinding ( TArray< FIndex3i >& TrianglesOut,
TArrayView< const TVector2< double >> Vertices,
TArrayView< const FIndex2i > Edges,
EFillMode FillMode
)

 Get (by reference) the triangles that are inside the given edges, using a generalized winding number method to determine which triangles are inside Not valid for EFillMode::Solid, will fall back to the above GetFilledTriangles method in that case.
Public function Const bool

GetFilledTrianglesGeneralizedWinding ( TArray< FIndex3i >& TrianglesOut,
TArrayView< const TVector2< float >> Vertices,
TArrayView< const FIndex2i > Edges,
EFillMode FillMode
)

 Get (by reference) the triangles that are inside the given edges, using a generalized winding number method to determine which triangles are inside Not valid for EFillMode::Solid, will fall back to the above GetFilledTriangles method in that case.
Public function Const TArray< FIndex3i > TODO: Support incremental vertex insertion Update the triangulation incrementally, assuming Vertices are unchanged before FirstNewIndex, and nothing after FirstNewIndex has been inserted yet Note that updating with new vertices after constraining edges may remove previously-constrained edges, unless we also add a way to tag constrained edges bool Update(TArrayView> Vertices, int32 FirstNewIdx); Get the triangulation as an array of triangles Note: This creates a new array each call, because the internal data structure does not have a triangle array
Public function Const void

GetTrianglesAndAdjacency ( TArray< FIndex3i >& Triangles,
TArray< FIndex3i >& Adjacency
)

 Get the triangulation as an array with a corresponding adjacency array, indicating the adjacent triangle on each triangle edge (-1 if no adjacent triangle)
Public function Const TArray< TArray< FVector2f > >

GetVoronoiCells ( TArrayView< const FVector2f > Vertices,
bool bIncludeBoundary,
FAxisAlignedBox2f ClipBounds,
float ExpandBounds
)

 Get Voronoi diagram cells as dual of the Delaunay triangulation.
Public function Const TArray< TArray< FVector2d > >

GetVoronoiCells ( TArrayView< const FVector2d > Vertices,
bool bIncludeBoundary,
FAxisAlignedBox2d ClipBounds,
double ExpandBounds
)

 Get Voronoi diagram cells as dual of the Delaunay triangulation.
Public function Const bool  
Public function bool

HasEdge ( const FIndex2i& Edge,
bool bRemapDuplicates
)

  
Public function Const bool

HasEdges ( TArrayView< const FIndex2i > Edges
)

  
Public function Const bool  
Public function Const bool

IsDelaunay ( TArrayView< const FVector2f > Vertices,
TArrayView< const FIndex2i > SkipEdges
)

  
Public function Const bool

IsDelaunay ( TArrayView< const FVector2d > Vertices,
TArrayView< const FIndex2i > SkipEdges
)

  
Public function Const int32

RemapIfDuplicate ( int32 Index
)

  
Public function bool

Triangulate ( TArrayView< const TVector2< double >> Vertices,
TArrayView< const FIndex2i > Edges
)

 TODO: it would often be useful to pass in sparse vertex data / Optional function to allow Triangulate to skip vertices.
Public function bool

Triangulate ( TArrayView< const TVector2< float >> Vertices,
TArrayView< const FIndex2i > Edges
)

 TODO: it would often be useful to pass in sparse vertex data / Optional function to allow Triangulate to skip vertices.
Public function bool

Triangulate ( const TPolygon2< RealType >& Polygon,
TArray< FIndex3i >* TrianglesOut
)

 Triangulate a polygon, and optionally pass back the resulting triangles Uses the 'solid' fill mode, and fills the polygon regardless of the edge orientation Note: TrianglesOut may be empty or incomplete if the input is self-intersecting.
Public function bool

Triangulate ( const TGeneralPolygon2< RealType >& GeneralPolygon,
TArray< FIndex3i >* TrianglesOut,
TArray< TVector2< RealType >>* VerticesOut,
bool bFallbackToGeneralizedWinding
)

 Triangulate a polygon, and optionally pass back the resulting triangles Uses a winding-number-based fill mode, and relies on the general polygon having correct orientations (Uses TGeneralPolygon2's OuterIsClockwise() to automatically choose between positive or negative winding) Note: TrianglesOut may be empty or incomplete if the input is self-intersecting.
Protected function Const bool

ValidateResult ( TArrayView< const FIndex2i > Edges
)

 Helper to perform standard validation on results after Triangulate or ConstrainEdges calls

Enums

  Type Name Description
Public enum EFillMode Options for selecting what triangles to include in the output, for constrained Delaunay triangulation of polygons.  

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