GEOS  3.8.0dev
Static Public Member Functions | Static Public Attributes | List of all members
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
tip1the tip of one vector
tailthe tail of each vector
tip2the 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
tip1the tip of v1
tailthe tail of each vector
tip2the 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
ang1the angle of one vector (in [-Pi, Pi] )
ang2the 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
ang1an angle (in radians)
ang2an 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
p0a point of the ring
p1the next point of the ring
p2the 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
p0an endpoint of the angle
p1the base of the angle
p2the 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
p0an endpoint of the angle
p1the base of the angle
p2the 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
anglethe 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
anglethe 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
radiansan angle in radians
Returns
the angle in degrees
static double geos::algorithm::Angle::toRadians ( double  angleDegrees)
static

Converts from degrees to radians.

Parameters
angleDegreesan angle in degrees
Returns
the angle in radians

The documentation for this class was generated from the following file: