orx/orx-easing/README.md

orx-easing

Easing functions for smooth animation or non-linear interpolation.

Similar to those on https://easings.net

type
linear	easeLinear
constant 0	easeZero
constant 1	easeOne

type	in	in out	out
quad	easeQuadIn	easeQuadInOut	easeQuadOut
cubic	easeCubicIn	easeCubicInOut	easeCubicOut
quart	easeQuartIn	easeQuartInOut	easeQuartOut
quint	easeQuintIn	easeQuintInOut	easeQuintOut
circ	easeCircIn	easeCircInOut	easeCircOut
expo	easeExpoIn	easeExpoInOut	easeExpoOut
sine	easeSineIn	easeSineInOut	easeSineOut
back	easeBackIn	easeBackInOut	easeBackOut
bounce	easeBounceIn	easeBounceInOut	easeBounceOut
elastic	easeElasticIn	easeElasticInOut	easeElasticOut

Usage

fun easeX(
  t: Double,       // current time
  b: Double = 0.0, // beginning (output value when t is 0.0)
  c: Double = 1.0, // change (output delta)
  d: Double = 1.0  // duration = end time
)

The most common usage involves repeatedly calling the easing function increasing the t argument while keeping other arguments unchanged. When t increases from 0.0 up to d, the returned value slides from b to b + c.

Example

For accelerating from 40.0 down to 10.0 in 10 steps:

repeat(10) {
    val y = easeQuadIn(it.toDouble(), 40.0, -30.0, 9.0)
    println("$it -> $y")
}

Outputs

0 -> 40.0
1 -> 39.629629629629626
2 -> 38.51851851851852
3 -> 36.666666666666664
4 -> 34.074074074074076
5 -> 30.74074074074074
6 -> 26.666666666666668
7 -> 21.85185185185185
8 -> 16.2962962962963
9 -> 10.0

Note how most result values are closer to 40.0 than to 10.0, due to the usage of an In easing function. easeCubicIn, easeQuartIn and easeQuinticIn functions would make this even more obvious.

Default arguments

When t is in [0, 1] we can omit most arguments

val e0 = easeQuadIn(t, 0.0, 1.0, 1.0)
val e1 = easeQuadIn(t)

Using the Easing enumeration

The Easing enum contains all easing functions.

val et = Easing.QuadIn.function(t, 0.0, 1.0, 1.0)

// list all easing function names
Easing.values().forEach { easing ->
    println(easing.name)
}

// find out how many easing functions are available
println(Easing.values().size)

Demos

DemoEasings01

Visualizes Easing types as a graph and as motion.

[grid] is used to layout graphs on rows and columns.

source code