Package org.geolatte.geom

Class Circle

java.lang.Object

org.geolatte.geom.Circle

public class Circle
extends Object

This class provides operations for handling the usage of Circles and arcs in Geometries.

Author:

Tom Acree

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
class	Circle.Arc	An arc, or circle segment

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	Circle()	Creates a circle whose center is at the origin and whose radius is 0.
	Circle(double xCenter, double yCenter, double radius)	Create a circle using the x/y coordinates for the center.
	Circle(double xLeft, double yUpper, double xRight, double yLower)	Creates a circle based on bounding box.
	Circle(double x1, double y1, double x2, double y2, double x3, double y3)	Three point method of circle construction.
	Circle(org.locationtech.jts.geom.Coordinate center, double radius)	Create a circle with a defined center and radius
	Circle(org.locationtech.jts.geom.Coordinate point1, org.locationtech.jts.geom.Coordinate point2, org.locationtech.jts.geom.Coordinate point3)	Three point method of circle construction.

Method Summary

Modifier and Type	Method	Description
Circle.Arc	createArc(org.locationtech.jts.geom.Coordinate p1, org.locationtech.jts.geom.Coordinate p2, org.locationtech.jts.geom.Coordinate p3)	Creates an arc through the specified points
double	distanceFromCenter(org.locationtech.jts.geom.Coordinate p)	Returns the distance the point is from the center of the circle
boolean	equals(Object o)
double	getAngle(org.locationtech.jts.geom.Coordinate p)	Returns the angle of the point from the center and the horizontal line from the center.
org.locationtech.jts.geom.Coordinate	getCenter()
org.locationtech.jts.geom.Coordinate	getPoint(double angle)	Returns the coordinate on the circle at the specified angle
double	getRadius()
int	hashCode()
static org.locationtech.jts.geom.Coordinate[]	linearizeArc(double x1, double y1, double x2, double y2, double x3, double y3)	Given 2 points defining an arc on the circle, interpolates the circle into a collection of points that provide connected chords that approximate the arc based on the tolerance value.
static org.locationtech.jts.geom.Coordinate[]	linearizeArc(double x1, double y1, double x2, double y2, double x3, double y3, double tolerence)	Given 2 points defining an arc on the circle, interpolates the circle into a collection of points that provide connected chords that approximate the arc based on the tolerance value.
org.locationtech.jts.geom.Coordinate[]	linearizeArc(org.locationtech.jts.geom.Coordinate p1, org.locationtech.jts.geom.Coordinate p2, org.locationtech.jts.geom.Coordinate p3, double tolerence)	Given 2 points defining an arc on the circle, interpolates the circle into a collection of points that provide connected chords that approximate the arc based on the tolerance value.
static org.locationtech.jts.geom.Coordinate[]	linearizeCircle(double x1, double y1, double x2, double y2, double x3, double y3)	Given a circle defined by the 3 points, creates a linearized interpolation of the circle starting and ending on the first coordinate.
void	move(double x, double y)	Moves the circle to a new center
static double	normalizeAngle(double angle)	Returns an angle between 0 and 2*PI.
void	shift(double deltaX, double deltaY)	Shifts the center of the circle by delta X and delta Y
static double	subtractAngles(double a1, double a2)	Returns the angle between the angles a1 and a2 in radians.
String	toString()

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

Circle

protected Circle()

Creates a circle whose center is at the origin and whose radius is 0.

Circle

public Circle(org.locationtech.jts.geom.Coordinate center,
              double radius)

Create a circle with a defined center and radius

Parameters:

center - The coordinate representing the center of the circle

radius - The radius of the circle

Circle

public Circle(double xCenter,
              double yCenter,
              double radius)

Create a circle using the x/y coordinates for the center.

Parameters:

xCenter - The x coordinate of the circle's center

yCenter - The y coordinate of the circle's center

radius - the radius of the circle

Circle

public Circle(double xLeft,
              double yUpper,
              double xRight,
              double yLower)

Creates a circle based on bounding box. It is possible for the user of this class to pass bounds to this method that do not represent a square. If this is the case, we must force the bounding rectangle to be a square. To this end, we check the box and set the side of the box to the larger dimension of the rectangle

Parameters:

xLeft - The leftmost x coordinate

yUpper - The uppermost y coordinate

xRight - The rightmost x coordinate

yLower - The lowest y coordinate

Circle

public Circle(org.locationtech.jts.geom.Coordinate point1,
              org.locationtech.jts.geom.Coordinate point2,
              org.locationtech.jts.geom.Coordinate point3)

Three point method of circle construction. All three points must be on the circumference of the circle.

Parameters:

point1 - The first point

point2 - The second point

point3 - The third point

Circle

public Circle(double x1,
              double y1,
              double x2,
              double y2,
              double x3,
              double y3)

Three point method of circle construction. All three points must be on the circumference of the circle.

Parameters:

x1 - The x coordinate of the first point

y1 - The y coordinate of the first point

x2 - The x coordinate of the second point

y2 - The y coordinate of the second point

x3 - The x coordinate of the third point

y3 - The y coordinate of the third point

Method Detail

linearizeArc

public static org.locationtech.jts.geom.Coordinate[] linearizeArc(double x1,
                                                                  double y1,
                                                                  double x2,
                                                                  double y2,
                                                                  double x3,
                                                                  double y3,
                                                                  double tolerence)

Given 2 points defining an arc on the circle, interpolates the circle into a collection of points that provide connected chords that approximate the arc based on the tolerance value. The tolerance value specifies the maximum distance between a chord and the circle.

Parameters:

x1 - x coordinate of point 1

y1 - y coordinate of point 1

x2 - x coordinate of point 2

y2 - y coordinate of point 2

x3 - x coordinate of point 3

y3 - y coordinate of point 3

tolerence - maximum distance between the center of the chord and the outer edge of the circle

Returns:

an ordered list of Coordinates representing a series of chords approximating the arc.

linearizeArc

public static org.locationtech.jts.geom.Coordinate[] linearizeArc(double x1,
                                                                  double y1,
                                                                  double x2,
                                                                  double y2,
                                                                  double x3,
                                                                  double y3)

Given 2 points defining an arc on the circle, interpolates the circle into a collection of points that provide connected chords that approximate the arc based on the tolerance value. This method uses a tolerence value of 1/100 of the length of the radius.

Parameters:

x1 - x coordinate of point 1

y1 - y coordinate of point 1

x2 - x coordinate of point 2

y2 - y coordinate of point 2

x3 - x coordinate of point 3

y3 - y coordinate of point 3

Returns:

an ordered list of Coordinates representing a series of chords approximating the arc.

linearizeCircle

public static org.locationtech.jts.geom.Coordinate[] linearizeCircle(double x1,
                                                                     double y1,
                                                                     double x2,
                                                                     double y2,
                                                                     double x3,
                                                                     double y3)

Given a circle defined by the 3 points, creates a linearized interpolation of the circle starting and ending on the first coordinate. This method uses a tolerence value of 1/100 of the length of the radius.

Parameters:

x1 - x coordinate of point 1

y1 - y coordinate of point 1

x2 - x coordinate of point 2

y2 - y coordinate of point 2

x3 - x coordinate of point 3

y3 - y coordinate of point 3

Returns:

an ordered list of Coordinates representing a series of chords approximating the arc.

normalizeAngle

public static double normalizeAngle(double angle)

Returns an angle between 0 and 2*PI. For example, 4*PI would get returned as 2*PI since they are equivalent.

Parameters:

angle - an angle in radians to normalize

Returns:

an angle between 0 and 2*PI

subtractAngles

public static double subtractAngles(double a1,
                                    double a2)

Returns the angle between the angles a1 and a2 in radians. Angle is calculated in the counterclockwise direction.

Parameters:

a1 - first angle

a2 - second angle

Returns:

the angle between a1 and a2 in the clockwise direction

shift

public void shift(double deltaX,
                  double deltaY)

Shifts the center of the circle by delta X and delta Y

Parameters:

deltaX - The shift along the X-coordinate axis

deltaY - The shift along the Y-coordinate axis

move

public void move(double x,
                 double y)

Moves the circle to a new center

Parameters:

x - The x coordinate of the new center

y - The y coordinate of the new center

getCenter

public org.locationtech.jts.geom.Coordinate getCenter()

getRadius

public double getRadius()

linearizeArc

public org.locationtech.jts.geom.Coordinate[] linearizeArc(org.locationtech.jts.geom.Coordinate p1,
                                                           org.locationtech.jts.geom.Coordinate p2,
                                                           org.locationtech.jts.geom.Coordinate p3,
                                                           double tolerence)

Given 2 points defining an arc on the circle, interpolates the circle into a collection of points that provide connected chords that approximate the arc based on the tolerance value. The tolerance value specifies the maximum distance between a chord and the circle.

Parameters:

p1 - begin coordinate of the arc

p2 - any other point on the arc

p3 - end coordinate of the arc

tolerence - maximum distance between the center of the chord and the outer edge of the circle

Returns:

an ordered list of Coordinates representing a series of chords approximating the arc.

equals

public boolean equals(Object o)

Overrides:

equals in class Object

hashCode

public int hashCode()

Overrides:

hashCode in class Object

toString

public String toString()

Overrides:

toString in class Object

getAngle

public double getAngle(org.locationtech.jts.geom.Coordinate p)

Returns the angle of the point from the center and the horizontal line from the center.

Parameters:

p - a point in space

Returns:

The angle of the point from the center of the circle

getPoint

public org.locationtech.jts.geom.Coordinate getPoint(double angle)

Returns the coordinate on the circle at the specified angle

Parameters:

angle - The angle

Returns:

Coordinate

distanceFromCenter

public double distanceFromCenter(org.locationtech.jts.geom.Coordinate p)

Returns the distance the point is from the center of the circle

Parameters:

p - A point in space

Returns:

The distance the point is from the center of the circle

createArc

public Circle.Arc createArc(org.locationtech.jts.geom.Coordinate p1,
                            org.locationtech.jts.geom.Coordinate p2,
                            org.locationtech.jts.geom.Coordinate p3)

Creates an arc through the specified points

Parameters:

p1 - The first point

p2 - The second point

p3 - The third point

Returns:

The Arc through the three points