Class AngleUtility

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

Inheritance

object

AngleUtility

Inherited Members

object.Equals(object)

object.Equals(object, object)

object.GetHashCode()

object.GetType()

object.MemberwiseClone()

object.ReferenceEquals(object, object)

object.ToString()

Namespace: NetTopologySuite.Algorithm

Assembly: NetTopologySuite.dll

Syntax

public static class AngleUtility

Fields

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PiOver2

Value of Pi / 2

Declaration

public const double PiOver2 = 1.5707963267948966

Field Value

Type	Description
double

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PiOver4

Value of Pi / 4

Declaration

public const double PiOver4 = 0.7853981633974483

Field Value

Type	Description
double

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PiTimes2

Value of 2 * Pi

Declaration

public const double PiTimes2 = 6.283185307179586

Field Value

Type	Description
double

Methods

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Angle(Coordinate)

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

Declaration

public static double Angle(Coordinate p)

Parameters

Type	Name	Description
Coordinate	p	The terminal point of the vector.

Returns

Type	Description
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 ].

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Angle(Coordinate, Coordinate)

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

Declaration

public static double Angle(Coordinate p0, Coordinate p1)

Parameters

Type	Name	Description
Coordinate	p0	The initial point of the vector.
Coordinate	p1	The terminal point of the vector.

Returns

Type	Description
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 ].

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AngleBetween(Coordinate, Coordinate, Coordinate)

Returns the unoriented smallest angle between two vectors.

Declaration

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

Parameters

Type	Name	Description
Coordinate	tip1	The tip of one vector
Coordinate	tail	The tail of each vector
Coordinate	tip2	The tip of the other vector

Returns

Type	Description
double

Remarks

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

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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.

Declaration

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

Parameters

Type	Name	Description
Coordinate	tip1	The tip of v1
Coordinate	tail	The tail of each vector
Coordinate	tip2	The tip of v2

Returns

Type	Description
double	The angle between v1 and v2, relative to v1

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Bisector(Coordinate, Coordinate, Coordinate)

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

Declaration

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

Parameters

Type	Name	Description
Coordinate	tip1	The tip of v1
Coordinate	tail	The tail of each vector
Coordinate	tip2	The tip of v2

Returns

Type	Description
double	The angle of the bisector between v1 and v2

Remarks

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

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CosSnap(double)

Computes Math.Cos of an angle, snapping near-zero values to zero.

Declaration

public static double CosSnap(double ang)

Parameters

Type	Name	Description
double	ang	The input angle (in radians)

Returns

Type	Description
double	The result of the trigonometric function

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Diff(double, double)

Computes the unoriented smallest difference between two angles.

Declaration

public static double Diff(double ang1, double ang2)

Parameters

Type	Name	Description
double	ang1	The angle of one vector (in [-Pi, Pi] )
double	ang2	The angle of the other vector (in range [-Pi, Pi] )

Returns

Type	Description
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].

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GetTurn(double, double)

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

Declaration

public static OrientationIndex GetTurn(double ang1, double ang2)

Parameters

Type	Name	Description
double	ang1	An angle (in radians)
double	ang2	An angle (in radians)

Returns

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

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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.

Declaration

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

Parameters

Type	Name	Description
Coordinate	p0	A point of the ring
Coordinate	p1	The next point of the ring
Coordinate	p2	The next point of the ring

Returns

Type	Description
double	The interior angle based at `p1`

Remarks

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

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IsAcute(Coordinate, Coordinate, Coordinate)

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

Declaration

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

Parameters

Type	Name	Description
Coordinate	p0	An endpoint of the angle
Coordinate	p1	The base of the angle
Coordinate	p2	Another endpoint of the angle

Returns

Type	Description
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.

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IsObtuse(Coordinate, Coordinate, Coordinate)

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

Declaration

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

Parameters

Type	Name	Description
Coordinate	p0	An endpoint of the angle
Coordinate	p1	The base of the angle
Coordinate	p2	Another endpoint of the angle

Returns

Type	Description
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.

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Normalize(double)

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

Declaration

public static double Normalize(double angle)

Parameters

Type	Name	Description
double	angle	The angle to normalize

Returns

Type	Description
double	An equivalent angle in the range (-Pi, Pi]

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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

Declaration

public static double NormalizePositive(double angle)

Parameters

Type	Name	Description
double	angle	The angle to normalize, in radians.

Returns

Type	Description
double	An equivalent positive angle

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Project(Coordinate, double, double)

Projects a point by a given angle and distance.

Declaration

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

Parameters

Type	Name	Description
Coordinate	p	The point to project
double	angle	The angle at which to project
double	dist	The distance to project

Returns

Type	Description
Coordinate	The projected point

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SinSnap(double)

Computes Math.Sin of an angle, snapping near-zero values to zero.

Declaration

public static double SinSnap(double ang)

Parameters

Type	Name	Description
double	ang	The input angle (in radians)

Returns

Type	Description
double	The result of the trigonometric function

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ToDegrees(double)

Converts from radians to degrees.

Declaration

public static double ToDegrees(double radians)

Parameters

Type	Name	Description
double	radians	An angle in radians

Returns

Type	Description
double	The angle in degrees

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ToRadians(double)

Converts from degrees to radians.

Declaration

public static double ToRadians(double angleDegrees)

Parameters

Type	Name	Description
double	angleDegrees	An angle in degrees

Returns

Type	Description
double	The angle in radians