# Class Rotation2d

java.lang.Object
edu.wpi.first.math.geometry.Rotation2d
All Implemented Interfaces:
Interpolatable<Rotation2d>

public class Rotation2d
extends Object
implements Interpolatable<Rotation2d>
A rotation in a 2D coordinate frame represented by a point on the unit circle (cosine and sine).

The angle is continuous, that is if a Rotation2d is constructed with 361 degrees, it will return 361 degrees. This allows algorithms that wouldn't want to see a discontinuity in the rotations as it sweeps past from 360 to 0 on the second time around.

• ## Constructor Summary

Constructors
Constructor Description
Rotation2d()
Constructs a Rotation2d with a default angle of 0 degrees.
Rotation2d​(double value)
Constructs a Rotation2d with the given radian value.
Rotation2d​(double x, double y)
Constructs a Rotation2d with the given x and y (cosine and sine) components.
• ## Method Summary

Modifier and Type Method Description
Rotation2d div​(double scalar)
Divides the current rotation by a scalar.
boolean equals​(Object obj)
Checks equality between this Rotation2d and another object.
static Rotation2d fromDegrees​(double degrees)
Constructs and returns a Rotation2d with the given degree value.
Constructs and returns a Rotation2d with the given radian value.
static Rotation2d fromRotations​(double rotations)
Constructs and returns a Rotation2d with the given number of rotations.
double getCos()
Returns the cosine of the Rotation2d.
double getDegrees()
Returns the degree value of the Rotation2d.
Returns the radian value of the Rotation2d.
double getRotations()
Returns the number of rotations of the Rotation2d.
double getSin()
Returns the sine of the Rotation2d.
double getTan()
Returns the tangent of the Rotation2d.
int hashCode()
Rotation2d interpolate​(Rotation2d endValue, double t)
Return the interpolated value.
Rotation2d minus​(Rotation2d other)
Subtracts the new rotation from the current rotation and returns the new rotation.
Rotation2d plus​(Rotation2d other)
Adds two rotations together, with the result being bounded between -pi and pi.
Rotation2d rotateBy​(Rotation2d other)
Adds the new rotation to the current rotation using a rotation matrix.
Rotation2d times​(double scalar)
Multiplies the current rotation by a scalar.
String toString()
Rotation2d unaryMinus()
Takes the inverse of the current rotation.

### Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait
• ## Constructor Details

• ### Rotation2d

public Rotation2d()
Constructs a Rotation2d with a default angle of 0 degrees.
• ### Rotation2d

public Rotation2d​(double value)
Constructs a Rotation2d with the given radian value.
Parameters:
value - The value of the angle in radians.
• ### Rotation2d

public Rotation2d​(double x, double y)
Constructs a Rotation2d with the given x and y (cosine and sine) components.
Parameters:
x - The x component or cosine of the rotation.
y - The y component or sine of the rotation.
• ## Method Details

Constructs and returns a Rotation2d with the given radian value.
Parameters:
Returns:
The rotation object with the desired angle value.
• ### fromDegrees

public static Rotation2d fromDegrees​(double degrees)
Constructs and returns a Rotation2d with the given degree value.
Parameters:
degrees - The value of the angle in degrees.
Returns:
The rotation object with the desired angle value.
• ### fromRotations

public static Rotation2d fromRotations​(double rotations)
Constructs and returns a Rotation2d with the given number of rotations.
Parameters:
rotations - The value of the angle in rotations.
Returns:
The rotation object with the desired angle value.
• ### plus

public Rotation2d plus​(Rotation2d other)
Adds two rotations together, with the result being bounded between -pi and pi.

For example, Rotation2d.fromDegrees(30).plus(Rotation2d.fromDegrees(60)) equals Rotation2d(Math.PI/2.0)

Parameters:
other - The rotation to add.
Returns:
The sum of the two rotations.
• ### minus

public Rotation2d minus​(Rotation2d other)
Subtracts the new rotation from the current rotation and returns the new rotation.

For example, Rotation2d.fromDegrees(10).minus(Rotation2d.fromDegrees(100)) equals Rotation2d(-Math.PI/2.0)

Parameters:
other - The rotation to subtract.
Returns:
The difference between the two rotations.
• ### unaryMinus

Takes the inverse of the current rotation. This is simply the negative of the current angular value.
Returns:
The inverse of the current rotation.
• ### times

public Rotation2d times​(double scalar)
Multiplies the current rotation by a scalar.
Parameters:
scalar - The scalar.
Returns:
The new scaled Rotation2d.
• ### div

public Rotation2d div​(double scalar)
Divides the current rotation by a scalar.
Parameters:
scalar - The scalar.
Returns:
The new scaled Rotation2d.
• ### rotateBy

public Rotation2d rotateBy​(Rotation2d other)
Adds the new rotation to the current rotation using a rotation matrix.

The matrix multiplication is as follows:

[cos_new]   [other.cos, -other.sin][cos]
[sin_new] = [other.sin,  other.cos][sin]
value_new = atan2(sin_new, cos_new)

Parameters:
other - The rotation to rotate by.
Returns:
The new rotated Rotation2d.

Returns the radian value of the Rotation2d.
Returns:
The radian value of the Rotation2d.
to constrain the angle within (-pi, pi]
• ### getDegrees

public double getDegrees()
Returns the degree value of the Rotation2d.
Returns:
The degree value of the Rotation2d.
to constrain the angle within (-180, 180]
• ### getRotations

public double getRotations()
Returns the number of rotations of the Rotation2d.
Returns:
The number of rotations of the Rotation2d.
• ### getCos

public double getCos()
Returns the cosine of the Rotation2d.
Returns:
The cosine of the Rotation2d.
• ### getSin

public double getSin()
Returns the sine of the Rotation2d.
Returns:
The sine of the Rotation2d.
• ### getTan

public double getTan()
Returns the tangent of the Rotation2d.
Returns:
The tangent of the Rotation2d.
• ### toString

public String toString()
Overrides:
toString in class Object
• ### equals

public boolean equals​(Object obj)
Checks equality between this Rotation2d and another object.
Overrides:
equals in class Object
Parameters:
obj - The other object.
Returns:
Whether the two objects are equal or not.
• ### hashCode

public int hashCode()
Overrides:
hashCode in class Object
• ### interpolate

public Rotation2d interpolate​(Rotation2d endValue, double t)
Description copied from interface: Interpolatable
Return the interpolated value. This object is assumed to be the starting position, or lower bound.
Specified by:
interpolate in interface Interpolatable<Rotation2d>
Parameters:
endValue - The upper bound, or end.
t - How far between the lower and upper bound we are. This should be bounded in [0, 1].
Returns:
The interpolated value.