Package org.bitbrawl.foodfight.util

Class Direction

java.lang.Object

org.bitbrawl.foodfight.util.Direction

@Immutable
public final class Direction
extends Object

A direction on 2-dimensional plane of the field. A direction is essentially an angle measurement, in radians. The directions used are the ones commonly used in math, where EAST is a direction of 0 and NORTH is a direction of ^π⁄₂. The angle measurement of a direction will always be in the range [0, 2π).

Author:

Finn

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	Direction.Deserializer	A deserializer for directions.
static class	Direction.Serializer	A serializer for directions.

Field Summary

Fields

Modifier and Type	Field	Description
static Direction	EAST	The direction with measurement 0.
static Direction	NORTH	The direction with measurement π⁄2.
static Direction	SOUTH	The direction with measurement 3π⁄2.
static Direction	WEST	The direction with measurement π.

Constructor Summary

Constructors

Constructor	Description
Direction(double direction)	Constructs a direction object with the given direction measurement.

Method Summary

Modifier and Type	Method	Description
Direction	add(double angle)	Adds the given amount to this direction, returning the result of the addition.
static double	difference(Direction alpha, Direction beta)	Returns the signed difference between two angles.
boolean	equals(Object other)
double	get()	Returns the measurement of this direction object, in radians, where EAST is 0.0 and measurements increase as they rotate counter-clockwise.
Direction	getOpposite()	Returns the direction that is the opposite of this one.
int	hashCode()
static Direction	random()	Returns a randomly-generated direction.
Direction	reflectAcrossX()	Reflects this direction across the x-axis, returning the result.
Direction	reflectAcrossY()	Reflects this direction across the y-axis, returning the result.
String	toString()

Methods inherited from class java.lang.Object

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

Field Detail

EAST

public static final Direction EAST

The direction with measurement 0.

NORTH

public static final Direction NORTH

The direction with measurement ^π⁄₂.

WEST

public static final Direction WEST

The direction with measurement π.

SOUTH

public static final Direction SOUTH

The direction with measurement ^3π⁄₂.

Constructor Detail

Direction

public Direction(double direction)

Constructs a direction object with the given direction measurement. Note that calling get() on the returned object may return something different than the passed-in direction measurement if the given measurement is outside the range [0, 2π). For example, ^9π⁄₄ would be converted to ^π⁄₄.

Parameters:

direction - the angle measurement of the desired direction

Throws:

IllegalArgumentException - if direction is not finite

Method Detail

random

public static Direction random()

Returns a randomly-generated direction. The returned directions are uniformly distributed on the range [0, 2π).

Returns:

a random direction

get

public double get()

Returns the measurement of this direction object, in radians, where EAST is 0.0 and measurements increase as they rotate counter-clockwise. Direction objects are immutable, so this will always return the same value.

Returns:

the angle measurement of this direction

add

public Direction add(double angle)

Adds the given amount to this direction, returning the result of the addition. Note that this direction is not modified by this method (because direction objects are immutable), but a new direction is created. Note that a negative number can be used to subtract from this direction, but if the result is outside the range [0, 2π), it will "wrap around."

Parameters:

angle - the angle to add to this direction's angle measurement

Returns:

the result of adding the angle to this direction

Throws:

IllegalArgumentException - if angle is not finite

getOpposite

public Direction getOpposite()

Returns the direction that is the opposite of this one. The returned angle will differ from this one by π. As an example, the opposite of a player's direction is the direction that they would move if they were to move backward.

Returns:

the opposite of this direction

reflectAcrossY

public Direction reflectAcrossY()

Reflects this direction across the y-axis, returning the result. This method does not modify the object it is called on. If the object that this method is called on has measurement θ, the resulting angle would have measurement π - θ, but in the range [0, 2π).

Returns:

the resulting direction after the reflection.

reflectAcrossX

public Direction reflectAcrossX()

Reflects this direction across the x-axis, returning the result. This method does not modify the object it is called on. If the object that this method is called on has measurement θ, the resulting angle would have measurement -θ, but in the range [0, 2π).

Returns:

the resulting direction after the reflection.

difference

public static double difference(Direction alpha,
                                Direction beta)

Returns the signed difference between two angles. If called on two directions with measurements α and β, the result would be β - α, but in the range [-π, π). If the add(double) method is used to add the result of this method to alpha, the resulting angle will be very close to beta, and will differ only due to issues with floating-point arithmetic.

Parameters:

alpha - the first angle

beta - the second angle

Returns:

the angular displacement of beta relative to alpha

equals

public boolean equals(Object other)

Overrides:

equals in class Object

hashCode

public int hashCode()

Overrides:

hashCode in class Object

toString

public String toString()

Overrides:

toString in class Object