Class AngleUtility

Namespace

NetTopologySuite.Algorithm

Assembly

NetTopologySuite.dll

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

public static class AngleUtility

Inheritance

object

AngleUtility

Inherited Members

object.GetType()

object.MemberwiseClone()

object.ToString()

object.Equals(object)

object.Equals(object, object)

object.ReferenceEquals(object, object)

object.GetHashCode()

Fields

PiOver2

Value of Pi / 2

public const double PiOver2 = 1.5707963267948966

Field Value

double

PiOver4

Value of Pi / 4

public const double PiOver4 = 0.7853981633974483

Field Value

double

PiTimes2

Value of 2 * Pi

public const double PiTimes2 = 6.283185307179586

Field Value

double

Methods

Angle(Coordinate)

Returns the angle of the vector from (0,0) to p, relative to the positive X-axis.

public static double Angle(Coordinate p)

Parameters

p Coordinate

The terminal point of the vector.

Returns

double

The normalized angle (in radians) that (0,0)-p makes with the positive X-axis.

Remarks

The angle is normalized to be in the range ( -Pi, Pi ].

Angle(Coordinate, Coordinate)

Returns the angle of the vector from p0 to p1, relative to the positive X-axis.

public static double Angle(Coordinate p0, Coordinate p1)

Parameters

p0 Coordinate

The initial point of the vector.

p1 Coordinate

The terminal point of the vector.

Returns

double

The normalized angle (in radians) that p0-p1 makes with the positive X-axis

Remarks

The angle is normalized to be in the range [ -Pi, Pi ].

AngleBetween(Coordinate, Coordinate, Coordinate)

Returns the unoriented smallest angle between two vectors.

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

Parameters

tip1 Coordinate

The tip of one vector

tail Coordinate

The tail of each vector

tip2 Coordinate

The tip of the other vector

Returns

double

Remarks

The computed angle will be in the range [0, Pi).

AngleBetweenOriented(Coordinate, Coordinate, Coordinate)

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 (CCW) from v1 to v2; a negative result corresponds to a Clockwise (CW) rotation; a zero result corresponds to no rotation.

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

Parameters

tip1 Coordinate

The tip of v1

tail Coordinate

The tail of each vector

tip2 Coordinate

The tip of v2

Returns

double

The angle between v1 and v2, relative to v1

Bisector(Coordinate, Coordinate, Coordinate)

Computes the angle of the unoriented bisector of the smallest angle between two vectors.

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

Parameters

tip1 Coordinate

The tip of v1

tail Coordinate

The tail of each vector

tip2 Coordinate

The tip of v2

Returns

double

The angle of the bisector between v1 and v2

Remarks

The computed angle will be in the range (-Pi, Pi].

Diff(double, double)

Computes the unoriented smallest difference between two angles.

public static double Diff(double ang1, double ang2)

Parameters

ang1 double

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

ang2 double

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

Returns

double

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

Remarks

• The angles are assumed to be normalized to the range [-Pi, Pi].
• The result will be in the range [0, Pi].

GetTurn(double, double)

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

public static OrientationIndex GetTurn(double ang1, double ang2)

Parameters

ang1 double

An angle (in radians)

ang2 double

An angle (in radians)

Returns

OrientationIndex

Whether a1 must turn Clockwise, CounterClockwise or None to overlap a2.

InteriorAngle(Coordinate, Coordinate, Coordinate)

Computes the interior angle between two segments of a ring. The ring is assumed to be oriented in a clockwise direction.

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

Parameters

p0 Coordinate

A point of the ring

p1 Coordinate

The next point of the ring

p2 Coordinate

The next point of the ring

Returns

double

The interior angle based at p1

Remarks

The computed angle will be in the range [0, 2Pi]

IsAcute(Coordinate, Coordinate, Coordinate)

Tests whether the angle between p0-p1-p2 is acute.

public static bool IsAcute(Coordinate p0, Coordinate p1, Coordinate p2)

Parameters

p0 Coordinate

An endpoint of the angle

p1 Coordinate

The base of the angle

p2 Coordinate

Another endpoint of the angle

Returns

bool

true if the angle is acute.

Remarks

An angle is acute if it is less than 90 degrees.

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

IsObtuse(Coordinate, Coordinate, Coordinate)

Tests whether the angle between p0-p1-p2 is obtuse

public static bool IsObtuse(Coordinate p0, Coordinate p1, Coordinate p2)

Parameters

p0 Coordinate

An endpoint of the angle

p1 Coordinate

The base of the angle

p2 Coordinate

Another endpoint of the angle

Returns

bool

true if the angle is obtuse.

Remarks

An angle is obtuse if it is greater than 90 degrees.

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

Normalize(double)

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

public static double Normalize(double angle)

Parameters

angle double

The angle to normalize

Returns

double

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

NormalizePositive(double)

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

E.g.

Function call	Result
NormalizePositive(0.0)	0.0
NormalizePositive(-PI)	PI
NormalizePositive(-2PI)	0.0
NormalizePositive(-3PI)	PI
NormalizePositive(-4PI)	0.0
NormalizePositive(PI)	PI
NormalizePositive(2PI)	0.0
NormalizePositive(3PI)	PI
NormalizePositive(4PI)	0.0

public static double NormalizePositive(double angle)

Parameters

angle double

The angle to normalize, in radians.

Returns

double

An equivalent positive angle

Project(Coordinate, double, double)

Projects a point by a given angle and distance.

public static Coordinate Project(Coordinate p, double angle, double dist)

Parameters

p Coordinate

The point to project

angle double

The angle at which to project

dist double

The distance to project

Returns

Coordinate

The projected point

ToDegrees(double)

Converts from radians to degrees.

public static double ToDegrees(double radians)

Parameters

radians double

An angle in radians

Returns

double

The angle in degrees

ToRadians(double)

Converts from degrees to radians.

public static double ToRadians(double angleDegrees)

Parameters

angleDegrees double

An angle in degrees

Returns

double

The angle in radians