com.vividsolutions.jts.algorithm
Class Angle

java.lang.Object
  com.vividsolutions.jts.algorithm.Angle

public class Angle
extends java.lang.Object

Utility functions for working with angles. Unless otherwise noted, methods in this class express angles in radians.

Field Summary

static int	CLOCKWISE Constant representing clockwise orientation
static int	COUNTERCLOCKWISE Constant representing counterclockwise orientation
static int	NONE Constant representing no orientation
static double	PI_OVER_2
static double	PI_OVER_4
static double	PI_TIMES_2

Constructor Summary

Angle()

Method Summary

static double	angle(Coordinate p) Returns the angle that the vector from (0,0) to p, relative to the positive X-axis.
static double	angle(Coordinate p0, Coordinate p1) Returns the angle of the vector from p0 to p1, relative to the positive X-axis.
static double	angleBetween(Coordinate tip1, Coordinate tail, Coordinate tip2) Returns the unoriented smallest angle between two vectors.
static double	angleBetweenOriented(Coordinate tip1, Coordinate tail, Coordinate tip2) Returns the oriented smallest angle between two vectors.
static double	diff(double ang1, double ang2) Computes the unoriented smallest difference between two angles.
static int	getTurn(double ang1, double ang2) Returns whether an angle must turn clockwise or counterclockwise to overlap another angle.
static double	interiorAngle(Coordinate p0, Coordinate p1, Coordinate p2) Computes the interior angle between two segments of a ring.
static boolean	isAcute(Coordinate p0, Coordinate p1, Coordinate p2) Tests whether the angle between p0-p1-p2 is acute.
static boolean	isObtuse(Coordinate p0, Coordinate p1, Coordinate p2) Tests whether the angle between p0-p1-p2 is obtuse.
static double	normalize(double angle) Computes the normalized value of an angle, which is the equivalent angle in the range ( -Pi, Pi ].
static double	normalizePositive(double angle) Computes the normalized positive value of an angle, which is the equivalent angle in the range [ 0, 2*Pi ).
static double	toDegrees(double radians) Converts from radians to degrees.
static double	toRadians(double angleDegrees) Converts from degrees to radians.

Methods inherited from class java.lang.Object

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

Field Detail

PI_TIMES_2

public static final double PI_TIMES_2

See Also:

Constant Field Values

PI_OVER_2

public static final double PI_OVER_2

See Also:

Constant Field Values

PI_OVER_4

public static final double PI_OVER_4

See Also:

Constant Field Values

COUNTERCLOCKWISE

public static final int COUNTERCLOCKWISE

Constant representing counterclockwise orientation

See Also:

Constant Field Values

CLOCKWISE

public static final int CLOCKWISE

Constant representing clockwise orientation

See Also:

Constant Field Values

NONE

public static final int NONE

Constant representing no orientation

See Also:

Constant Field Values

Constructor Detail

Angle

public Angle()

Method Detail

toDegrees

public static double toDegrees(double radians)

Converts from radians to degrees.

Parameters:

radians - an angle in radians

Returns:

the angle in degrees

toRadians

public static double toRadians(double angleDegrees)

Converts from degrees to radians.

Parameters:

angleDegrees - an angle in degrees

Returns:

the angle in radians

angle

public static double angle(Coordinate p0,
                           Coordinate p1)

Returns the angle of the vector from p0 to p1, relative to the positive X-axis. The angle is normalized to be in the range [ -Pi, Pi ].

Returns:

the normalized angle (in radians) that p0-p1 makes with the positive x-axis.

angle

public static double angle(Coordinate p)

Returns the angle that the vector from (0,0) to p, relative to the positive X-axis. The angle is normalized to be in the range ( -Pi, Pi ].

Returns:

the normalized angle (in radians) that p makes with the positive x-axis.

isAcute

public static boolean isAcute(Coordinate p0,
                              Coordinate p1,
                              Coordinate p2)

Tests whether the angle between p0-p1-p2 is acute. An angle is acute if it is less than 90 degrees.

Note: this implementation is not precise (determistic) for angles very close to 90 degrees.

Parameters:

p0 - an endpoint of the angle

p1 - the base of the angle

p2 - the other endpoint of the angle

isObtuse

public static boolean isObtuse(Coordinate p0,
                               Coordinate p1,
                               Coordinate p2)

Tests whether the angle between p0-p1-p2 is obtuse. An angle is obtuse if it is greater than 90 degrees.

Note: this implementation is not precise (determistic) for angles very close to 90 degrees.

Parameters:

p0 - an endpoint of the angle

p1 - the base of the angle

p2 - the other endpoint of the angle

angleBetween

public static double angleBetween(Coordinate tip1,
                                  Coordinate tail,
                                  Coordinate tip2)

Returns the unoriented smallest angle between two vectors. The computed angle will be in the range [0, Pi).

Parameters:

tip1 - the tip of one vector

tail - the tail of each vector

tip2 - the tip of the other vector

Returns:

the angle between tail-tip1 and tail-tip2

angleBetweenOriented

public static double angleBetweenOriented(Coordinate tip1,
                                          Coordinate tail,
                                          Coordinate tip2)

Returns the oriented smallest angle between two vectors. The computed angle will be in the range (-Pi, Pi]. A positive result corresponds to a counterclockwise rotation from v1 to v2; a negative result corresponds to a clockwise rotation.

Parameters:

tip1 - the tip of v1

tail - the tail of each vector

tip2 - the tip of v2

Returns:

the angle between v1 and v2, relative to v1

interiorAngle

public static double interiorAngle(Coordinate p0,
                                   Coordinate p1,
                                   Coordinate p2)

Computes the interior angle between two segments of a ring. The ring is assumed to be oriented in a clockwise direction. The computed angle will be in the range [0, 2Pi]

Parameters:

p0 - a point of the ring

p1 - the next point of the ring

p2 - the next point of the ring

Returns:

the interior angle based at p1

getTurn

public static int getTurn(double ang1,
                          double ang2)

Returns whether an angle must turn clockwise or counterclockwise to overlap another angle.

Parameters:

ang1 - an angle (in radians)

ang2 - an angle (in radians)

Returns:

whether a1 must turn CLOCKWISE, COUNTERCLOCKWISE or NONE to overlap a2.

normalize

public static double normalize(double angle)

Computes the normalized value of an angle, which is the equivalent angle in the range ( -Pi, Pi ].

Parameters:

angle - the angle to normalize

Returns:

an equivalent angle in the range (-Pi, Pi]

normalizePositive

public static double normalizePositive(double angle)

Computes the normalized positive value of an angle, which is the equivalent angle in the range [ 0, 2*Pi ). E.g.:

• normalizePositive(0.0) = 0.0
• normalizePositive(-PI) = PI
• normalizePositive(-2PI) = 0.0
• normalizePositive(-3PI) = PI
• normalizePositive(-4PI) = 0
• normalizePositive(PI) = PI
• normalizePositive(2PI) = 0.0
• normalizePositive(3PI) = PI
• normalizePositive(4PI) = 0.0

Parameters:

angle - the angle to normalize, in radians

Returns:

an equivalent positive angle

diff

public static double diff(double ang1,
                          double ang2)

Computes the unoriented smallest difference between two angles. The angles are assumed to be normalized to the range [-Pi, Pi]. The result will be in the range [0, Pi].

Parameters:

ang1 - the angle of one vector (in [-Pi, Pi] )

ang2 - the angle of the other vector (in range [-Pi, Pi] )

Returns:

the angle (in radians) between the two vectors (in range [0, Pi] )