Package org.joml

Class PolygonsIntersection

java.lang.Object

org.joml.PolygonsIntersection

public class PolygonsIntersection
extends Object

Class for polygon/point intersection tests when testing many points against one or many static concave or convex, simple polygons.

This is an implementation of the algorithm described in http://alienryderflex.com and augmented with using a custom interval tree to avoid testing all polygon edges against a point, but only those that intersect the imaginary ray along the same y co-ordinate of the search point. This algorithm additionally also supports multiple polygons.

This class is thread-safe and can be used in a multithreaded environment when testing many points against the same polygon concurrently.

Reference: http://alienryderflex.com

Author:

Kai Burjack

Field Summary

Fields

Modifier and Type	Field	Description
protected final float[]	verticesXY

Constructor Summary

Constructors

Constructor	Description
PolygonsIntersection(float[] verticesXY, int[] polygons, int count)	Create a new PolygonsIntersection object with the given polygon vertices.

Method Summary

Modifier and Type	Method	Description
boolean	testPoint(float x, float y)	Test whether the given point (x, y) lies inside any polygon stored in this PolygonsIntersection object.
boolean	testPoint(float x, float y, BitSet inPolys)	Test whether the given point (x, y) lies inside any polygon stored in this PolygonsIntersection object.

Methods inherited from class java.lang.Object

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

Field Details

verticesXY

protected final float[] verticesXY

Constructor Details

PolygonsIntersection

public PolygonsIntersection(float[] verticesXY,
 int[] polygons,
 int count)

Create a new PolygonsIntersection object with the given polygon vertices.

The verticesXY array contains the x and y coordinates of all vertices. This array will not be copied so its content must remain constant for as long as the PolygonPointIntersection is used with it.

Parameters:

verticesXY - contains the x and y coordinates of all vertices

polygons - defines the start vertices of a new polygon. The first vertex of the first polygon is always the vertex with index 0. In order to define a hole simply define a polygon that is completely inside another polygon

count - the number of vertices to use from the verticesXY array, staring with index 0

Method Details

testPoint

public boolean testPoint(float x,
 float y)

Test whether the given point (x, y) lies inside any polygon stored in this PolygonsIntersection object.

This method is thread-safe and can be used to test many points concurrently.

In order to obtain the index of the polygon the point is inside of, use testPoint(float, float, BitSet)

Parameters:

x - the x coordinate of the point to test

y - the y coordinate of the point to test

Returns:

true iff the point lies inside any polygon; false otherwise

See Also:

• testPoint(float, float, BitSet)

testPoint

public boolean testPoint(float x,
 float y,
 BitSet inPolys)

Test whether the given point (x, y) lies inside any polygon stored in this PolygonsIntersection object.

This method is thread-safe and can be used to test many points concurrently.

Parameters:

x - the x coordinate of the point to test

y - the y coordinate of the point to test

inPolys - if not null then the i-th bit is set if the given point is inside the i-th polygon

Returns:

true iff the point lies inside the polygon and not inside a hole; false otherwise