Package org.apache.commons.geometry.spherical.oned

Class Transform1S

java.lang.Object

org.apache.commons.geometry.spherical.oned.Transform1S

All Implemented Interfaces:

Function<Point1S,Point1S>, UnaryOperator<Point1S>, Transform<Point1S>

public final class Transform1S
extends Object
implements Transform<Point1S>

Implementation of the Transform interface for spherical 1D points.

Similar to the Euclidean 1D AffineTransformMatrix1D, this class performs transformations using an internal 1D affine transformation matrix. In the Euclidean case, the matrix contains a scale factor and a translation. Here, the matrix contains a scale/negation factor that takes the values -1 or +1, and a rotation value. This restriction on the allowed values in the matrix is required in order to fulfill the geometric requirements of the Transform interface. For example, if arbitrary scaling is allowed, the point 0.5pi could be scaled by 4 to 2pi, which is equivalent to 0pi. However, if the inverse scaling of 1/4 is applied to 0pi, the result is 0pi and not 0.5pi. This breaks the Transform requirement that transforms be inversible.

Instances of this class are guaranteed to be immutable.

Field Summary

Fields

Modifier and Type	Field	Description
private static final Transform1S	IDENTITY	Static instance representing the identity transform.
private static final Transform1S	NEGATION	Static instance that negates azimuth values.
private final double	rotate	Value to rotate the point azimuth by.
private final double	scale	Value to scale the point azimuth by.

Constructor Summary

Constructors

Modifier	Constructor	Description
private	Transform1S(double scale, double rotate)	Construct a new instance from its transform components.

Method Summary

Modifier and Type	Method	Description
Point1S	apply(Point1S pt)
static Transform1S	createNegation()	Return a transform instance that negates azimuth values.
static Transform1S	createRotation(double angle)	Return a transform instance that performs a rotation with the given angle.
boolean	equals(Object obj)	Return true if the given object is an instance of Transform1S and all transform element values are exactly equal.
double	getRotation()	Get the rotation value applied by this instance, in radians.
int	hashCode()
static Transform1S	identity()	Return a transform instance representing the identity transform.
Transform1S	inverse()	Get an instance representing the inverse transform.
boolean	isNegation()	Return true if the transform negates the azimuth values of transformed points, regardless of any rotation applied subsequently.
Transform1S	multiply(Transform1S other)	Multiply the underlying matrix of this instance by that of the argument, eg, other * this.
private static Transform1S	multiply(Transform1S a, Transform1S b)	Multiply two transforms together as matrices.
Transform1S	negate()	Return a new transform created by pre-multiplying this instance by a transform that negates azimuth values.
Transform1S	premultiply(Transform1S other)	Multiply the underlying matrix of the argument by that of this instance, eg, this * other.
boolean	preservesOrientation()	Return true if the transform preserves the orientation of the space.
Transform1S	rotate(double angle)	Return a new transform created by pre-multiplying this instance by a transform producing a rotation with the given angle.
String	toString()

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface java.util.function.Function

andThen, compose

Field Details

IDENTITY

private static final Transform1S IDENTITY

Static instance representing the identity transform.

NEGATION

private static final Transform1S NEGATION

Static instance that negates azimuth values.

scale

private final double scale

Value to scale the point azimuth by. This will only be +1/-1.

rotate

private final double rotate

Value to rotate the point azimuth by.

Constructor Details

Transform1S

private Transform1S(double scale,
 double rotate)

Construct a new instance from its transform components.

Parameters:

scale - scale value for the transform; must only be +1 or -1

rotate - rotation value

Method Details

isNegation

public boolean isNegation()

Return true if the transform negates the azimuth values of transformed points, regardless of any rotation applied subsequently.

Returns:

true if the transform negates the azimuth values of transformed points

See Also:

• preservesOrientation()

getRotation

public double getRotation()

Get the rotation value applied by this instance, in radians.

Returns:

the rotation value applied by this instance, in radians.

apply

public Point1S apply(Point1S pt)

Specified by:

apply in interface Function<Point1S,Point1S>

preservesOrientation

public boolean preservesOrientation()

Return true if the transform preserves the orientation of the space. For example, in Euclidean 2D space, this will be true for translations, rotations, and scalings but will be false for reflections.

Specified by:

preservesOrientation in interface Transform<Point1S>

Returns:

true if the transform preserves the orientation of the space

See Also:

• Orientation

rotate

public Transform1S rotate(double angle)

Return a new transform created by pre-multiplying this instance by a transform producing a rotation with the given angle.

Parameters:

angle - angle to rotate, in radians

Returns:

a new transform created by pre-multiplying this instance by a transform producing a rotation with the given angle

See Also:

• createRotation(double)

negate

public Transform1S negate()

Return a new transform created by pre-multiplying this instance by a transform that negates azimuth values.

Returns:

a new transform created by pre-multiplying this instance by a transform that negates azimuth values

multiply

public Transform1S multiply(Transform1S other)

Multiply the underlying matrix of this instance by that of the argument, eg, other * this. The returned transform performs the equivalent of other followed by this.

Parameters:

other - transform to multiply with

Returns:

a new transform computed by multiplying the matrix of this instance by that of the argument

premultiply

public Transform1S premultiply(Transform1S other)

Multiply the underlying matrix of the argument by that of this instance, eg, this * other. The returned transform performs the equivalent of this followed by other.

Parameters:

other - transform to multiply with

Returns:

a new transform computed by multiplying the matrix of the argument by that of this instance

inverse

public Transform1S inverse()

Get an instance representing the inverse transform.

Specified by:

inverse in interface Transform<Point1S>

Returns:

an instance representing the inverse transform

hashCode

public int hashCode()

Overrides:

hashCode in class Object

equals

public boolean equals(Object obj)

Return true if the given object is an instance of Transform1S and all transform element values are exactly equal.

Overrides:

equals in class Object

Parameters:

obj - object to test for equality with the current instance

Returns:

true if all transform elements are exactly equal; otherwise false

toString

public String toString()

Overrides:

toString in class Object

identity

public static Transform1S identity()

Return a transform instance representing the identity transform.

Returns:

a transform instance representing the identity transform

createNegation

public static Transform1S createNegation()

Return a transform instance that negates azimuth values.

Returns:

a transform instance that negates azimuth values.

createRotation

public static Transform1S createRotation(double angle)

Return a transform instance that performs a rotation with the given angle.

Parameters:

angle - angle of the rotation, in radians

Returns:

a transform instance that performs a rotation with the given angle

multiply

private static Transform1S multiply(Transform1S a,
 Transform1S b)

Multiply two transforms together as matrices.

Parameters:

a - first transform

b - second transform

Returns:

the transform computed as a x b