math.geom2d.polygon
Class SimplePolygon2D

java.lang.Object
  math.geom2d.polygon.SimplePolygon2D

All Implemented Interfaces:

CirculinearDomain2D, CirculinearShape2D, Domain2D, GeometricObject2D, Polygon2D, Shape2D

public class SimplePolygon2D
extends java.lang.Object
implements Polygon2D

Represent a polygonal domain whose boundary is a single closed polyline.

Field Summary

Fields inherited from interface math.geom2d.Shape2D

ACCURACY

Constructor Summary

SimplePolygon2D()
Empty constructor: no vertex.

SimplePolygon2D(java.util.Collection<? extends Point2D> points)

SimplePolygon2D(double[] xcoords, double[] ycoords)
Constructor from two arrays, one for each coordinate.

SimplePolygon2D(LinearRing2D ring)
Creates a simple polygon with the given linear ring representing its boundary.

SimplePolygon2D(Point2D... vertices)
Constructor from an array of points

Method Summary

void	addVertex(Point2D point) Adds a point as the last vertex.
boolean	almostEquals(GeometricObject2D obj, double eps) Checks if the two objects are similar up to a given threshold value.
double	area() Computes the signed area of the polygon.
Polygon2D	asPolygon(int n) Returns an approximation of the domain as a polygon, or a MultiPolygon.
CirculinearContourArray2D<LinearRing2D>	boundary() Returns a set of one LinearRing2D, which encloses the polygon.
Box2D	boundingBox() Returns the bounding box of the polygon.
CirculinearDomain2D	buffer(double dist) Computes the buffer of the shape, formed by the set of points located at a distance from the shape that is lower or equal to d.
Point2D	centroid() Computes the centroid (center of mass) of the polygon.
void	clearVertices() Removes all the vertices of the polygon.
Polygon2D	clip(Box2D box) Returns the shape formed by the polygon clipped by the given box.
SimplePolygon2D	clone()
int	closestVertexIndex(Point2D point) Computes the index of the closest vertex to the input point.
SimplePolygon2D	complement() Returns the polygon created by reversing the order of the vertices.
boolean	contains(double x, double y) Returns true if the point (x, y) lies inside the polygon, with precision given by Shape2D.ACCURACY.
boolean	contains(Point2D p) Returns true if the point p lies inside the polygon, with precision given by Shape2D.ACCURACY.
java.util.Collection<LinearRing2D>	contours() Returns the set of contours that enclose this domain.
static SimplePolygon2D	create(java.util.Collection<? extends Point2D> points) Static factory for creating a new SimplePolygon2D from a collection of points.
static SimplePolygon2D	create(Point2D... points) Static factory for creating a new SimplePolygon2D from an array of points.
double	distance(double x, double y) Returns the distance of the point to the polygon.
double	distance(Point2D p) Returns the distance of the point to the polygon.
void	draw(java.awt.Graphics2D g2) Draws the shape on the given graphics.
int	edgeNumber() Returns the number of edges.
java.util.Collection<LineSegment2D>	edges() Returns the set of edges, as a collection of LineSegment2D.
boolean	equals(java.lang.Object obj) Tests if the two polygons are equal.
void	fill(java.awt.Graphics2D g) Fills the interior of the domain, using the Graphics current Paint.
java.awt.geom.GeneralPath	getGeneralPath() Returns a general path iterator.
LinearRing2D	getRing() Returns the linear ring that composes the boundary of this polygon.
int	getWindingNumber(double x, double y) Computes the winding number of the polygon.
void	insertVertex(int index, Point2D point) Adds a point as the last vertex.
boolean	isBounded() Returns true if polygon is oriented counter-clockwise, false otherwise.
boolean	isEmpty() Returns true if the shape does not contain any point.
void	removeVertex(int index) Removes a vertex of the polygon specified by its index.
boolean	removeVertex(Point2D point) Removes a vertex of the polygon.
void	setVertex(int index, Point2D position) Changes the position of the i-th vertex.
SimplePolygon2D	transform(AffineTransform2D trans) Returns the new Polygon created by an affine transform of this polygon.
CirculinearDomain2D	transform(CircleInversion2D inv) Transforms the shape by a circle inversion.
Point2D	vertex(int i) Returns the i-th vertex of the polygon.
int	vertexNumber() Returns the number of vertices of the polygon.
java.util.Collection<Point2D>	vertices() Returns the points of the polygon.

Methods inherited from class java.lang.Object

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

Constructor Detail

SimplePolygon2D

public SimplePolygon2D()

Empty constructor: no vertex.

SimplePolygon2D

public SimplePolygon2D(Point2D... vertices)

Constructor from an array of points

Parameters:

vertices - the vertices stored in an array of Point2D

SimplePolygon2D

public SimplePolygon2D(double[] xcoords,
                       double[] ycoords)

Constructor from two arrays, one for each coordinate.

Parameters:

xcoords - the x coordinate of each vertex

ycoords - the y coordinate of each vertex

SimplePolygon2D

public SimplePolygon2D(java.util.Collection<? extends Point2D> points)

SimplePolygon2D

public SimplePolygon2D(LinearRing2D ring)

Creates a simple polygon with the given linear ring representing its boundary.

Parameters:

ring - the boundary of the polygon

Method Detail

create

public static SimplePolygon2D create(java.util.Collection<? extends Point2D> points)

Static factory for creating a new SimplePolygon2D from a collection of points.

Since:

0.8.1

create

public static SimplePolygon2D create(Point2D... points)

Static factory for creating a new SimplePolygon2D from an array of points.

Since:

0.8.1

getWindingNumber

public int getWindingNumber(double x,
                            double y)

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

Parameters:

x - the x-coordinate of the point

y - the y-coordinate of the point

Returns:

the number of windings of the curve around the point

getRing

public LinearRing2D getRing()

Returns the linear ring that composes the boundary of this polygon.

Since:

0.9.3

addVertex

public void addVertex(Point2D point)

Adds a point as the last vertex.

Specified by:

addVertex in interface Polygon2D

Parameters:

point - the position of the new vertex

insertVertex

public void insertVertex(int index,
                         Point2D point)

Adds a point as the last vertex.

Specified by:

insertVertex in interface Polygon2D

Parameters:

index - index at which the specified vertex is to be inserted

point - the position of the new vertex

Since:

0.9.3

setVertex

public void setVertex(int index,
                      Point2D position)

Changes the position of the i-th vertex.

Specified by:

setVertex in interface Polygon2D

Parameters:

index - the vertex index

position - the new position of the vertex

removeVertex

public boolean removeVertex(Point2D point)

Removes a vertex of the polygon.

Parameters:

point - the vertex to be removed.

removeVertex

public void removeVertex(int index)

Removes a vertex of the polygon specified by its index.

Specified by:

removeVertex in interface Polygon2D

Parameters:

index - index of the vertex to remove

Since:

0.9.3

clearVertices

public void clearVertices()

Removes all the vertices of the polygon.

closestVertexIndex

public int closestVertexIndex(Point2D point)

Computes the index of the closest vertex to the input point.

Specified by:

closestVertexIndex in interface Polygon2D

area

public double area()

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

Specified by:

area in interface Polygon2D

Returns:

the signed area of the polygon.

centroid

public Point2D centroid()

Computes the centroid (center of mass) of the polygon. Algorithm is taken from page: http://local.wasp.uwa.edu.au/~pbourke/geometry/polyarea/.

Specified by:

centroid in interface Polygon2D

Returns:

the centroid of the polygon

vertices

public java.util.Collection<Point2D> vertices()

Returns the points of the polygon. The result is a pointer to the inner collection of vertices.

Specified by:

vertices in interface Polygon2D

vertex

public Point2D vertex(int i)

Returns the i-th vertex of the polygon.

Specified by:

vertex in interface Polygon2D

Parameters:

i - index of the vertex, between 0 and the number of vertices

vertexNumber

public int vertexNumber()

Returns the number of vertices of the polygon.

Specified by:

vertexNumber in interface Polygon2D

Since:

0.6.3

edges

public java.util.Collection<LineSegment2D> edges()

Returns the set of edges, as a collection of LineSegment2D.

Specified by:

edges in interface Polygon2D

edgeNumber

public int edgeNumber()

Returns the number of edges. For a simple polygon, this equals the number of vertices.

Specified by:

edgeNumber in interface Polygon2D

transform

public CirculinearDomain2D transform(CircleInversion2D inv)

Description copied from interface: CirculinearShape2D

Transforms the shape by a circle inversion. The result is still an instance a CirculinearShape2D.

Specified by:

transform in interface CirculinearDomain2D

Specified by:

transform in interface CirculinearShape2D

Parameters:

inv - the circle inversion

Returns:

the transformed shape

buffer

public CirculinearDomain2D buffer(double dist)

Description copied from interface: CirculinearShape2D

Computes the buffer of the shape, formed by the set of points located at a distance from the shape that is lower or equal to d.

Specified by:

buffer in interface CirculinearShape2D

Parameters:

dist - the maximal distance between a point of the buffer and the shape

Returns:

the buffer of the shape

asPolygon

public Polygon2D asPolygon(int n)

Description copied from interface: Domain2D

Returns an approximation of the domain as a polygon, or a MultiPolygon.

Specified by:

asPolygon in interface Domain2D

Returns:

a polygon

boundary

public CirculinearContourArray2D<LinearRing2D> boundary()

Returns a set of one LinearRing2D, which encloses the polygon.

Specified by:

boundary in interface CirculinearDomain2D

Specified by:

boundary in interface Domain2D

Specified by:

boundary in interface Polygon2D

Returns:

the boundary of the domain

contours

public java.util.Collection<LinearRing2D> contours()

Description copied from interface: Domain2D

Returns the set of contours that enclose this domain. The result is a collection of shapes that implement the Contour2D interface.

Specified by:

contours in interface CirculinearDomain2D

Specified by:

contours in interface Domain2D

Specified by:

contours in interface Polygon2D

See Also:

Contour2D

complement

public SimplePolygon2D complement()

Returns the polygon created by reversing the order of the vertices.

Specified by:

complement in interface CirculinearDomain2D

Specified by:

complement in interface Domain2D

Specified by:

complement in interface Polygon2D

Returns:

the polygon complementary to this

distance

public double distance(Point2D p)

Returns the distance of the point to the polygon. The result is the minimal distance computed for each edge if the polygon, or ZERO if the point lies inside the polygon.

Specified by:

distance in interface Shape2D

distance

public double distance(double x,
                       double y)

Returns the distance of the point to the polygon. The result is the minimal distance computed for each edge if the polygon, or ZERO if the point lies inside the polygon.

Specified by:

distance in interface Shape2D

clip

public Polygon2D clip(Box2D box)

Returns the shape formed by the polygon clipped by the given box.

Specified by:

clip in interface Domain2D

Specified by:

clip in interface Polygon2D

Specified by:

clip in interface Shape2D

Parameters:

box - the clipping box

Returns:

the clipped shape

boundingBox

public Box2D boundingBox()

Returns the bounding box of the polygon.

Specified by:

boundingBox in interface Shape2D

Returns:

the bounding box of the shape.

isBounded

public boolean isBounded()

Returns true if polygon is oriented counter-clockwise, false otherwise.

Specified by:

isBounded in interface Shape2D

isEmpty

public boolean isEmpty()

Description copied from interface: Shape2D

Returns true if the shape does not contain any point. This is the case for example for PointSet2D without any point.

Specified by:

isEmpty in interface Shape2D

Returns:

true if the shape does not contain any point.

transform

public SimplePolygon2D transform(AffineTransform2D trans)

Returns the new Polygon created by an affine transform of this polygon. If the transform is not direct, the order of vertices is reversed.

Specified by:

transform in interface Domain2D

Specified by:

transform in interface Polygon2D

Specified by:

transform in interface Shape2D

Parameters:

trans - an affine transform

Returns:

the transformed shape

contains

public boolean contains(Point2D p)

Returns true if the point p lies inside the polygon, with precision given by Shape2D.ACCURACY.

Specified by:

contains in interface Shape2D

contains

public boolean contains(double x,
                        double y)

Returns true if the point (x, y) lies inside the polygon, with precision given by Shape2D.ACCURACY.

Specified by:

contains in interface Shape2D

getGeneralPath

public java.awt.geom.GeneralPath getGeneralPath()

Returns a general path iterator.

draw

public void draw(java.awt.Graphics2D g2)

Description copied from interface: Shape2D

Draws the shape on the given graphics. If the shape is empty, nothing is drawn. If the shape is unbounded, an exception is thrown.

Specified by:

draw in interface Domain2D

Specified by:

draw in interface Shape2D

Parameters:

g2 - the Graphics to draw on

fill

public void fill(java.awt.Graphics2D g)

Description copied from interface: Domain2D

Fills the interior of the domain, using the Graphics current Paint.

Specified by:

fill in interface Domain2D

Parameters:

g - the Graphics to fill on

almostEquals

public boolean almostEquals(GeometricObject2D obj,
                            double eps)

Description copied from interface: GeometricObject2D

Checks if the two objects are similar up to a given threshold value. This method can be used to compare the results of geometric computations, that introduce errors due to numerical computations.

Specified by:

almostEquals in interface GeometricObject2D

Parameters:

obj - the object to compare

eps - a threshold value, for example the minimal coordinate difference

Returns:

true if both object have the same value up to the threshold

equals

public boolean equals(java.lang.Object obj)

Tests if the two polygons are equal. Test first the number of vertices, then the bounding boxes, then if each vertex of the polygon is contained in the vertices array of this polygon.

Overrides:

equals in class java.lang.Object

clone

public SimplePolygon2D clone()

Overrides:

clone in class java.lang.Object