1. Epic GamesDeveloper
  3. FArrangement2d

FArrangement2d

Arrangement2d constructs a planar arrangement of a set of 2D line segments.

Unreal Engine C++ API Reference > Plugins > GeometryAlgorithms

References

   
Module GeometryAlgorithms
Header /Engine/Plugins/Runtime/GeometryProcessing/Source/GeometryAlgorithms/Public/Arrangement2d.h
Include #include "Arrangement2d.h"

Syntax

struct FArrangement2d

Remarks

Arrangement2d constructs a planar arrangement of a set of 2D line segments. When a segment is inserted, existing edges are split, and the inserted segment becomes multiple graph edges. So, the resulting FDynamicGraph2d should not have any edges that intersect.

Calculations are performed in double-precision, so there is no guarantee of correctness.

[TODO] multi-level segment has to accelerate find_intersecting_edges() [TODO] maybe smarter handling

Variables

  Type Name Description
Public variable *void int GID  
Public variable FDynamicGraph2d Graph Graph of arrangement
Public variable TPointHashGrid2d< int > PointHash PointHash for vertices of graph.
Public variable double VertexSnapTol Points within this tolerance are merged

Constructors

  Type Name Description
Public function  

FArrangement2d ( const FAxisAlignedBox2d& BoundsHint
)

  
Public function  

FArrangement2d ( double PointHashCellSize
)

  

Functions

  Type Name Description
Public function int

find_existing_vertex ( FVector2d Pt
)

 Find existing vertex at point, if it exists
Public function bool

find_intersecting_edges ( FVector2d A,
FVector2d B,
TArray< FIntersection >& Hits,
double Tol
)

 Find set of edges in graph that intersect with edge [A,B]
Public function bool

find_intersecting_floating_vertices ( const FSegment2d& SegAB,
int32 AID,
int32 BID,
TArray< FSegmentPoint >& Hits,
double Tol
)

  
Public function int

find_nearest_boundary_vertex ( FVector2d Pt,
double SearchRadius,
int IgnoreVID
)

 Find nearest boundary vertex, within SearchRadius
Public function int

find_nearest_vertex ( FVector2d Pt,
double SearchRadius,
int IgnoreVID
)

 Find closest vertex, within SearchRadius
Public function bool Check if current Graph has self-intersections; not optimized, only for debugging
Public function bool

HasVertexNear ( FVector2d Point,
double SearchRadius
)

 Check if vertex exists in region
Public function void

Insert ( const FSegment2d& Segment,
int GID
)

 Insert segment into the arrangement
Public function int

Insert ( const FVector2d& Pt
)

 Insert isolated point P into the arrangement
Public function void

Insert ( const FVector2d& A,
const FVector2d& B,
int GID
)

 Insert segment [A,B] into the arrangement
Public function Const *void

Insert ( PolyLine2d pline,
int GID
)

 Int N = pline.VertexCount - 1; for (int i = 0; i < N; ++i) { FVector2d A = pline[i]; FVector2d B = pline[i + 1]; insert_segment(A, B, GID); }
Public function int

insert_point ( const FVector2d& P,
double Tol
)

 Insert pt P into the arrangement, splitting existing edges as necessary
Public function bool

insert_segment ( FVector2d A,
FVector2d B,
int GID,
double Tol
)

 Insert edge [A,B] into the arrangement, splitting existing edges as necessary
Public function int32

InsertNewIsolatedPointUnsafe ( const FVector2d& Pt
)

 Insert isolated point P into the arrangement when you know by construction it's not too close to any vertex or edge Much faster, but will break things if you use it to insert a point that is on top of any existing element!
Public function FIndex2i

split_segment_at_t ( int EID,
double T,
double Tol
)

 Insert new point into segment EID at parameter value T If T is within Tol of endpoint of segment, we use that instead.
Public function FIndex2i

SplitEdgeAtPoint ( int EdgeID,
FVector2d Point
)

 Subdivide edge at a given position
Public function bool

Triangulate ( TArray< FIndex3i >& Triangles
)

 Attempts to triangulate the arrangement with a constrained Delaunay triangulation NOTE: May fail if arrangement has self-intersections
Public function bool

TriangulateWithBoundary ( TArray< FIndex3i >& Triangles,
int32 BoundaryEdgeGroupID
)

 Attempts to triangulate the arrangement with a constrained Delaunay triangulation NOTE: May fail if arrangement has self-intersections
Public function bool

TriangulateWithBoundaryAndHoles ( TArray< FIndex3i >& Triangles,
int32 BoundaryEdgeGroupID,
int32 HoleEdgeGroupID
)

 Attempts to triangulate the arrangement with a constrained Delaunay triangulation NOTE: May fail if arrangement has self-intersections

Classes

  Type Name Description
Public struct FIntersection    

Deprecated Functions

  Type Name Description
Public function bool

AttemptTriangulate ( TArray< FIntVector >& Triangles,
TArray< int32 >& SkippedEdges,
int32 BoundaryEdgeGroupID
)

 Please use the Triangulate or TriangulateWithBoundary functions instead, which are explicit about whether a BoundaryEdgeGroupID should be present
Public function bool

AttemptTriangulate ( TArray< FIndex3i >& Triangles,
TArray< int32 >& SkippedEdges,
int32 BoundaryEdgeGroupID
)

 Please use the Triangulate or TriangulateWithBoundary functions instead, which are explicit about whether a BoundaryEdgeGroupID should be present

Ask questions and help your peers Developer Forums

Write your own tutorials or read those from others Learning Library

On this page
Back to top
Games
Marketplaces
Tools
Online Services
Resources
Company

© 2004-2025, Epic Games, Inc. All rights reserved. Unreal and its logo are Epic’s trademarks or registered trademarks in the US and elsewhere.