Angle

Angle

Angle is an inline class backed by a Double that represents an angle and that can give additional type safety and semantics to code. It can be constructed from and converted to degrees, radians and ratio and offer several utilities and operators related to angles:

Predefined angles

There are some already-defined angles to be used:

val Angle.EPSILON = Angle.fromRatio(0.00001)
val Angle.ZERO = 0.degrees
val Angle.QUARTER = 90.degrees
val Angle.HALF = 180.degrees
val Angle.THREE_QUARTERS = 270.degrees
val Angle.FULL = 360.degrees

Constructing from ratio, radians or degrees

You can construct an Angle from a ratio, radians or degrees.

val angle = Angle.fromRatio(0.5)
val angle = Angle.fromRadians(PI)
val angle = Angle.fromDegrees(180)

Or with numeric extension properties:

val angle = PI.radians
val angle = 180.degrees

Getting radians, degrees or ratios from an angle

From an Angle instance, we can get the degrees, radians or ratio:

val angle: Angle = Angle.HALF
val radians: Double = angle.radians
val degrees: Double = angle.degrees
val ratio: Double = angle.ratio

Arithmetic

It is possible to add, subtract two angles, or multiply divide angles between scalars. There are also min, max, abs and clamp functions available:

val angle: Angle = 15.degrees + PI.radians - Angle.HALF
val angleX2: Angle = 15.degrees * 2
val angleNeg: Angle = -(15.degrees)
val angleMod: Angle = 45.degrees % 15.degrees
val ratio: Double = 45.degrees / 15.degrees
val abs: Angle = (-15).degrees.absoluteValue
val min: Angle = min(angle1, angle2)
val max: Angle = max(angle1, angle2)
val clamped: Angle = angle.clamp(15.degrees, 30.degrees)

You can check if an angle is in an angle range:

val range = 15.degrees until 32.degrees
val inside = 20.degrees in range

Sine, Cosine & Tangent

You can get the cosine (X), sine (Y) or tangent (Y/X) with:

fun cos(angle: Angle, up: Vector2 = Vector2.UP): Float
fun sin(angle: Angle, up: Vector2 = Vector2.UP): Float
fun tan(angle: Angle, up: Vector2 = Vector2.UP): Float

val x = angle.cosine
val y = angle.sine
val tan = angle.tangent

Since in KorGE, coordinates are X+ right, and Y+ down, while typical Y+ is up, you can provide a parameter to cosine to specify the vector representing up or what value would have y for 90.degrees:

val x = angle.cosine(Vector2.UP_SCREEN)
val y = angle.sine(Vector2.UP_SCREEN)
val tan = angle.tangent(Vector2.UP_SCREEN)

There are two standard provided up vectors Vector2.UP (Y+ up) and Vector2.UP_SCREEN (Y+ down)

Arc Sine/Cosine/Tangent

It is possible to get angles from Arc Cosine, Arc Sine and Arc Tangent:

fun Angle.arcCosine(v: Double): Angle
fun Angle.arcSine(v: Double): Angle
fun Angle.arcTangent(x: Double, y: Double): Angle

Normalizing angle

Sometimes we have an angle greater than 360 degrees or lesser than 0 degrees. This normalization will provide the angle in the [0, 360[ degrees range

val Angle.normalized: Angle

Angular distance between two angles

Either the short angle or the long one.

val shortDistance: Angle = Angle.shortDistanceTo(15.degrees, 350.degrees)
val longDistance: Angle = Angle.longDistanceTo(15.degrees, 350.degrees)

Angle interpolation

It is possible to interpolate two angles:

val ratio: Ratio = 0.5.toRatio()
val angle1 = 15.degrees
val angle2 = 45.degrees

val newAngle = ratio.interpolateAngle(angle1, angle2, minimizeAngle = true)
val newAngle = ratio.interpolateAngleNormalized(angle1, angle2)
val newAngle = ratio.interpolateAngleDenormalized(angle1, angle2)

Angle between two points

It is possible to determine the angle that two points form, by using the Angle.between or Point.angle methods. You can also provide the UP vector, either: Vector2D.UP (Y+ up) or Vector2D.UP_SCREEN (Y+ down).

val angle1 = Angle.between(Point(10, 10), Point(30, 30), Vector2D.UP_SCREEN)
val angle1 = Point.angle(Point(10, 10), Point(30, 30), Vector2D.UP_SCREEN)