GEOS  3.8.0dev
geos::algorithm::Angle Class Reference

Utility functions for working with angles. More...

`#include <Angle.h>`

## Static Public Member Functions

static double toDegrees (double radians)
Converts from radians to degrees. More...

static double toRadians (double angleDegrees)
Converts from degrees to radians. More...

static double angle (const geom::Coordinate &p0, const geom::Coordinate &p1)
Returns the angle of the vector from p0 to p1, relative to the positive X-axis. More...

static double angle (const geom::Coordinate &p)
Returns the angle that the vector from (0,0) to p, relative to the positive X-axis. More...

static bool isAcute (const geom::Coordinate &p0, const geom::Coordinate &p1, const geom::Coordinate &p2)
Tests whether the angle between p0-p1-p2 is acute. More...

static bool isObtuse (const geom::Coordinate &p0, const geom::Coordinate &p1, const geom::Coordinate &p2)
Tests whether the angle between p0-p1-p2 is obtuse. More...

static double angleBetween (const geom::Coordinate &tip1, const geom::Coordinate &tail, const geom::Coordinate &tip2)
Returns the unoriented smallest angle between two vectors. More...

static double angleBetweenOriented (const geom::Coordinate &tip1, const geom::Coordinate &tail, const geom::Coordinate &tip2)
Returns the oriented smallest angle between two vectors. More...

static double interiorAngle (const geom::Coordinate &p0, const geom::Coordinate &p1, const geom::Coordinate &p2)
Computes the interior angle between two segments of a ring. More...

static int getTurn (double ang1, double ang2)
Returns whether an angle must turn clockwise or counterclockwise to overlap another angle. More...

static double normalize (double angle)
Computes the normalized value of an angle, which is the equivalent angle in the range ( -Pi, Pi ]. More...

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

static double diff (double ang1, double ang2)
Computes the unoriented smallest difference between two angles. More...

## Static Public Attributes

static const double PI_TIMES_2

static const double PI_OVER_2

static const double PI_OVER_4

static const int COUNTERCLOCKWISE = Orientation::COUNTERCLOCKWISE
Constant representing counterclockwise orientation.

static const int CLOCKWISE = Orientation::CLOCKWISE
Constant representing clockwise orientation.

static const int NONE = Orientation::COLLINEAR
Constant representing no orientation.

## Detailed Description

Utility functions for working with angles.

Unless otherwise noted, methods in this class express angles in radians.

## Member Function Documentation

 static double geos::algorithm::Angle::angle ( const geom::Coordinate & p0, const geom::Coordinate & p1 )
static

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.
 static double geos::algorithm::Angle::angle ( const geom::Coordinate & p )
static

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.
 static double geos::algorithm::Angle::angleBetween ( const geom::Coordinate & tip1, const geom::Coordinate & tail, const geom::Coordinate & tip2 )
static

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
 static double geos::algorithm::Angle::angleBetweenOriented ( const geom::Coordinate & tip1, const geom::Coordinate & tail, const geom::Coordinate & tip2 )
static

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
 static double geos::algorithm::Angle::diff ( double ang1, double ang2 )
static

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] )
 static int geos::algorithm::Angle::getTurn ( double ang1, double ang2 )
static

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.
 static double geos::algorithm::Angle::interiorAngle ( const geom::Coordinate & p0, const geom::Coordinate & p1, const geom::Coordinate & p2 )
static

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`
 static bool geos::algorithm::Angle::isAcute ( const geom::Coordinate & p0, const geom::Coordinate & p1, const geom::Coordinate & p2 )
static

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
 static bool geos::algorithm::Angle::isObtuse ( const geom::Coordinate & p0, const geom::Coordinate & p1, const geom::Coordinate & p2 )
static

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
 static double geos::algorithm::Angle::normalize ( double angle )
static

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]
 static double geos::algorithm::Angle::normalizePositive ( double angle )
static

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
 static double geos::algorithm::Angle::toDegrees ( double radians )
static

Converts from radians to degrees.

Parameters