Package org.locationtech.jts.triangulate

Class VoronoiDiagramBuilder

java.lang.Object

org.locationtech.jts.triangulate.VoronoiDiagramBuilder

public class VoronoiDiagramBuilder
extends java.lang.Object

A utility class which creates Voronoi Diagrams from collections of points. The diagram is returned as a GeometryCollection of Polygons representing the faces of the Voronoi diagram. The faces are clipped to the larger of:

• an envelope supplied by setClipEnvelope(Envelope)
• an envelope determined by the input sites

The userData attribute of each face Polygon is set to the Coordinate of the corresponding input site. This allows using a Map to link faces to data associated with sites.

Field Summary

Fields

Modifier and Type	Field	Description
private Envelope	clipEnv
private Envelope	diagramEnv
private java.util.Collection	siteCoords
private QuadEdgeSubdivision	subdiv
private double	tolerance

Constructor Summary

Constructors

Constructor	Description
VoronoiDiagramBuilder()	Creates a new Voronoi diagram builder.

Method Summary

Modifier and Type	Method	Description
private static Geometry	clipGeometryCollection(Geometry geom, Envelope clipEnv)
private void	create()
Geometry	getDiagram(GeometryFactory geomFact)	Gets the faces of the computed diagram as a GeometryCollection of Polygons, clipped as specified.
QuadEdgeSubdivision	getSubdivision()	Gets the QuadEdgeSubdivision which models the computed diagram.
void	setClipEnvelope(Envelope clipEnv)	Sets the envelope to clip the diagram to.
void	setSites(java.util.Collection coords)	Sets the sites (point or vertices) which will be diagrammed from a collection of Coordinates.
void	setSites(Geometry geom)	Sets the sites (point or vertices) which will be diagrammed.
void	setTolerance(double tolerance)	Sets the snapping tolerance which will be used to improved the robustness of the triangulation computation.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

siteCoords

private java.util.Collection siteCoords

tolerance

private double tolerance

subdiv

private QuadEdgeSubdivision subdiv

clipEnv

private Envelope clipEnv

diagramEnv

private Envelope diagramEnv

Constructor Detail

VoronoiDiagramBuilder

public VoronoiDiagramBuilder()

Creates a new Voronoi diagram builder.

Method Detail

setSites

public void setSites(Geometry geom)

Sets the sites (point or vertices) which will be diagrammed. All vertices of the given geometry will be used as sites.

Parameters:

geom - the geometry from which the sites will be extracted.

setSites

public void setSites(java.util.Collection coords)

Sets the sites (point or vertices) which will be diagrammed from a collection of Coordinates.

Parameters:

coords - a collection of Coordinates.

setClipEnvelope

public void setClipEnvelope(Envelope clipEnv)

Sets the envelope to clip the diagram to. The diagram will be clipped to the larger of this envelope or an envelope surrounding the sites.

Parameters:

clipEnv - the clip envelope.

setTolerance

public void setTolerance(double tolerance)

Sets the snapping tolerance which will be used to improved the robustness of the triangulation computation. A tolerance of 0.0 specifies that no snapping will take place.

Parameters:

tolerance - the tolerance distance to use

create

private void create()

getSubdivision

public QuadEdgeSubdivision getSubdivision()

Gets the QuadEdgeSubdivision which models the computed diagram.

Returns:

the subdivision containing the triangulation

getDiagram

public Geometry getDiagram(GeometryFactory geomFact)

Gets the faces of the computed diagram as a GeometryCollection of Polygons, clipped as specified.

The userData attribute of each face Polygon is set to the Coordinate of the corresponding input site. This allows using a Map to link faces to data associated with sites.

Parameters:

geomFact - the geometry factory to use to create the output

Returns:

a GeometryCollection containing the face Polygons of the diagram

clipGeometryCollection

private static Geometry clipGeometryCollection(Geometry geom,
                                               Envelope clipEnv)