math.geom2d.polygon

Class Polygons2D

java.lang.Object

math.geom2d.polygon.Polygons2D

public final class Polygons2D
extends java.lang.Object

Several utility functions for working on polygons, including polygon creation, and basic computations such as polygon area or centroid.

Constructor Summary

Constructors

Constructor and Description
Polygons2D()

Method Summary

Modifier and Type	Method and Description
static Polygon2D	clipPolygon(Polygon2D polygon, Box2D box) Clips a polygon by a box.
static double	computeArea(LinearRing2D ring) Computes the signed area of the linear ring.
static double	computeArea(Polygon2D polygon) Computes the signed area of the polygon.
static Point2D	computeCentroid(LinearRing2D ring) Computes the centroid of the given linear ring.
static Point2D	computeCentroid(Polygon2D polygon) Computes the centroid of the given polygon.
static Polygon2D	convexHull(java.util.Collection<? extends Point2D> points) Returns the convex hull of the given set of points.
static CirculinearDomain2D	createBuffer(Polygon2D polygon, double dist) Computes the buffer at a distance d of the input polygon.
static SimplePolygon2D	createCenteredRectangle(Point2D center, double length, double width) Creates a new polygon representing a rectangle centered around a point.
static SimplePolygon2D	createOrientedRectangle(Point2D center, double length, double width, double theta) Creates a new polygon representing an oriented rectangle centered around a point.
static SimplePolygon2D	createRectangle(double x1, double y1, double x2, double y2) Creates a new polygon representing a rectangle with edges parallel to the main directions, and having the two specified opposite corners.
static SimplePolygon2D	createRectangle(Point2D p1, Point2D p2) Creates a new polygon representing a rectangle with edges parallel to the main directions, and having the two specified opposite corners.
static int	windingNumber(java.util.Collection<Point2D> vertices, Point2D point) Computes the winding number of the polygon.

Methods inherited from class java.lang.Object

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

Constructor Detail

Polygons2D

public Polygons2D()

Method Detail

createRectangle

public static final SimplePolygon2D createRectangle(Point2D p1,
                                                    Point2D p2)

Creates a new polygon representing a rectangle with edges parallel to the main directions, and having the two specified opposite corners.

Since:

0.10.3

createRectangle

public static final SimplePolygon2D createRectangle(double x1,
                                                    double y1,
                                                    double x2,
                                                    double y2)

Creates a new polygon representing a rectangle with edges parallel to the main directions, and having the two specified opposite corners.

Since:

0.10.3

createCenteredRectangle

public static final SimplePolygon2D createCenteredRectangle(Point2D center,
                                                            double length,
                                                            double width)

Creates a new polygon representing a rectangle centered around a point. Rectangle sides are parallel to the main axes. The function returns an instance of SimplePolygon2D.

Since:

0.9.1

createOrientedRectangle

public static final SimplePolygon2D createOrientedRectangle(Point2D center,
                                                            double length,
                                                            double width,
                                                            double theta)

Creates a new polygon representing an oriented rectangle centered around a point. The function returns an instance of SimplePolygon2D.

Since:

0.9.1

computeCentroid

public static final Point2D computeCentroid(Polygon2D polygon)

Computes the centroid of the given polygon.

Since:

0.9.1

computeCentroid

public static final Point2D computeCentroid(LinearRing2D ring)

Computes the centroid of the given linear ring.

Since:

0.9.1

computeArea

public static final double computeArea(Polygon2D polygon)

Computes the signed area of the polygon. Algorithm is taken from page: http://local.wasp.uwa.edu.au/~pbourke/geometry/polyarea/. Signed area is positive if polygon is oriented counter-clockwise, and negative otherwise. Result is wrong if polygon is self-intersecting.

Returns:

the signed area of the polygon.

Since:

0.9.1

computeArea

public static final double computeArea(LinearRing2D ring)

Computes the signed area of the linear ring. Algorithm is taken from page: http://local.wasp.uwa.edu.au/~pbourke/geometry/polyarea/. Signed area is positive if linear ring is oriented counter-clockwise, and negative otherwise. Result is wrong if linear ring is self-intersecting.

Returns:

the signed area of the polygon.

Since:

0.9.1

windingNumber

public static final int windingNumber(java.util.Collection<Point2D> vertices,
                                      Point2D point)

Computes the winding number of the polygon. Algorithm adapted from http://www.geometryalgorithms.com/Archive/algorithm_0103/algorithm_0103.htm http://softsurfer.com/Archive/algorithm_0103/algorithm_0103.htm

Parameters:

vertices - the vertices of a polygon

point - the reference point

Returns:

the number of windings of the curve around the point

convexHull

public static final Polygon2D convexHull(java.util.Collection<? extends Point2D> points)

Returns the convex hull of the given set of points. Uses the Jarvis March algorithm.

Parameters:

points - a collection of points

Returns:

the convex hull of the set of points

createBuffer

public static final CirculinearDomain2D createBuffer(Polygon2D polygon,
                                                     double dist)

Computes the buffer at a distance d of the input polygon. The result is a domain whose boundary is composed of line segments and circle arcs.

See Also:

CirculinearShape2D.buffer(double)

clipPolygon

public static final Polygon2D clipPolygon(Polygon2D polygon,
                                          Box2D box)

Clips a polygon by a box. The result is a new polygon, that can be multiple.

See Also:

Polygon2D.clip(Box2D)