Package org.apache.lucene.geo

Class Tessellator

java.lang.Object

org.apache.lucene.geo.Tessellator

public final class Tessellator
extends Object

Computes a triangular mesh tessellation for a given polygon.

This is inspired by mapbox's earcut algorithm (https://github.com/mapbox/earcut) which is a modification to FIST (https://www.cosy.sbg.ac.at/~held/projects/triang/triang.html) written by Martin Held, and ear clipping (https://www.geometrictools.com/Documentation/TriangulationByEarClipping.pdf) written by David Eberly.

Notes:

• Requires valid polygons:
  • No self intersections
  • Holes may only touch at one vertex
  • Polygon must have an area (e.g., no "line" boxes)
  • sensitive to overflow (e.g, subatomic values such as E-200 can cause unexpected behavior)

The code is a modified version of the javascript implementation provided by MapBox under the following license:

ISC License

Copyright (c) 2016, Mapbox

Permission to use, copy, modify, and/or distribute this software for any purpose with or without fee is hereby granted, provided that the above copyright notice and this permission notice appear in all copies.

THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH' REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.

NOTE: This API is for internal purposes only and might change in incompatible ways in the next release.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static interface	Tessellator.Monitor	Implementation of this interface will receive calls with internal data at each step of the triangulation algorithm.
static final class	Tessellator.Triangle	Triangle in the tessellated mesh

Method Summary

Modifier and Type	Method	Description
static boolean	linesIntersect(double aX0, double aY0, double aX1, double aY1, double bX0, double bY0, double bX1, double bY1)	Determines whether two line segments intersect.
static List<Tessellator.Triangle>	tessellate(Polygon polygon, boolean checkSelfIntersections)
static List<Tessellator.Triangle>	tessellate(Polygon polygon, boolean checkSelfIntersections, Tessellator.Monitor monitor)
static List<Tessellator.Triangle>	tessellate(XYPolygon polygon, boolean checkSelfIntersections)
static List<Tessellator.Triangle>	tessellate(XYPolygon polygon, boolean checkSelfIntersections, Tessellator.Monitor monitor)

Methods inherited from class java.lang.Object

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

Method Details

tessellate

public static List<Tessellator.Triangle> tessellate(Polygon polygon,
 boolean checkSelfIntersections)

tessellate

public static List<Tessellator.Triangle> tessellate(Polygon polygon,
 boolean checkSelfIntersections,
 Tessellator.Monitor monitor)

tessellate

public static List<Tessellator.Triangle> tessellate(XYPolygon polygon,
 boolean checkSelfIntersections)

tessellate

public static List<Tessellator.Triangle> tessellate(XYPolygon polygon,
 boolean checkSelfIntersections,
 Tessellator.Monitor monitor)

linesIntersect

public static boolean linesIntersect(double aX0,
 double aY0,
 double aX1,
 double aY1,
 double bX0,
 double bY0,
 double bX1,
 double bY1)

Determines whether two line segments intersect. *