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@Fonserbc
Last active August 27, 2024 23:41
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Compact and simple easing functions for Unity
using UnityEngine;
/*
* Most functions taken from Tween.js - Licensed under the MIT license
* at https://github.com/sole/tween.js
* Quadratic.Bezier by @fonserbc - Licensed under WTFPL license
*/
public delegate float EasingFunction(float k);
public class Easing
{
public static float Linear (float k) {
return k;
}
public class Quadratic
{
public static float In (float k) {
return k*k;
}
public static float Out (float k) {
return k*(2f - k);
}
public static float InOut (float k) {
if ((k *= 2f) < 1f) return 0.5f*k*k;
return -0.5f*((k -= 1f)*(k - 2f) - 1f);
}
/*
* Quadratic.Bezier(k,0) behaves like Quadratic.In(k)
* Quadratic.Bezier(k,1) behaves like Quadratic.Out(k)
*
* If you want to learn more check Alan Wolfe's post about it http://www.demofox.org/bezquad1d.html
*/
public static float Bezier (float k, float c) {
return c*2*k*(1 - k) + k*k;
}
};
public class Cubic
{
public static float In (float k) {
return k*k*k;
}
public static float Out (float k) {
return 1f + ((k -= 1f)*k*k);
}
public static float InOut (float k) {
if ((k *= 2f) < 1f) return 0.5f*k*k*k;
return 0.5f*((k -= 2f)*k*k + 2f);
}
};
public class Quartic
{
public static float In (float k) {
return k*k*k*k;
}
public static float Out (float k) {
return 1f - ((k -= 1f)*k*k*k);
}
public static float InOut (float k) {
if ((k *= 2f) < 1f) return 0.5f*k*k*k*k;
return -0.5f*((k -= 2f)*k*k*k - 2f);
}
};
public class Quintic
{
public static float In (float k) {
return k*k*k*k*k;
}
public static float Out (float k) {
return 1f + ((k -= 1f)*k*k*k*k);
}
public static float InOut (float k) {
if ((k *= 2f) < 1f) return 0.5f*k*k*k*k*k;
return 0.5f*((k -= 2f)*k*k*k*k + 2f);
}
};
public class Sinusoidal
{
public static float In (float k) {
return 1f - Mathf.Cos(k*Mathf.PI/2f);
}
public static float Out (float k) {
return Mathf.Sin(k*Mathf.PI/2f);
}
public static float InOut (float k) {
return 0.5f*(1f - Mathf.Cos(Mathf.PI*k));
}
};
public class Exponential
{
public static float In (float k) {
return k == 0f? 0f : Mathf.Pow(1024f, k - 1f);
}
public static float Out (float k) {
return k == 1f? 1f : 1f - Mathf.Pow(2f, -10f*k);
}
public static float InOut (float k) {
if (k == 0f) return 0f;
if (k == 1f) return 1f;
if ((k *= 2f) < 1f) return 0.5f*Mathf.Pow(1024f, k - 1f);
return 0.5f*(-Mathf.Pow(2f, -10f*(k - 1f)) + 2f);
}
};
public class Circular
{
public static float In (float k) {
return 1f - Mathf.Sqrt(1f - k*k);
}
public static float Out (float k) {
return Mathf.Sqrt(1f - ((k -= 1f)*k));
}
public static float InOut (float k) {
if ((k *= 2f) < 1f) return -0.5f*(Mathf.Sqrt(1f - k*k) - 1);
return 0.5f*(Mathf.Sqrt(1f - (k -= 2f)*k) + 1f);
}
};
public class Elastic
{
public static float In (float k) {
if (k == 0) return 0;
if (k == 1) return 1;
return -Mathf.Pow( 2f, 10f*(k -= 1f))*Mathf.Sin((k - 0.1f)*(2f*Mathf.PI)/0.4f);
}
public static float Out (float k) {
if (k == 0) return 0;
if (k == 1) return 1;
return Mathf.Pow(2f, -10f*k)*Mathf.Sin((k - 0.1f)*(2f*Mathf.PI)/0.4f) + 1f;
}
public static float InOut (float k) {
if ((k *= 2f) < 1f) return -0.5f*Mathf.Pow(2f, 10f*(k -= 1f))*Mathf.Sin((k - 0.1f)*(2f*Mathf.PI)/0.4f);
return Mathf.Pow(2f, -10f*(k -= 1f))*Mathf.Sin((k - 0.1f)*(2f*Mathf.PI)/0.4f)*0.5f + 1f;
}
};
public class Back
{
static float s = 1.70158f;
static float s2 = 2.5949095f;
public static float In (float k) {
return k*k*((s + 1f)*k - s);
}
public static float Out (float k) {
return (k -= 1f)*k*((s + 1f)*k + s) + 1f;
}
public static float InOut (float k) {
if ((k *= 2f) < 1f) return 0.5f*(k*k*((s2 + 1f)*k - s2));
return 0.5f*((k -= 2f)*k*((s2 + 1f)*k + s2) + 2f);
}
};
public class Bounce
{
public static float In (float k) {
return 1f - Out(1f - k);
}
public static float Out (float k) {
if (k < (1f/2.75f)) {
return 7.5625f*k*k;
}
else if (k < (2f/2.75f)) {
return 7.5625f*(k -= (1.5f/2.75f))*k + 0.75f;
}
else if (k < (2.5f/2.75f)) {
return 7.5625f *(k -= (2.25f/2.75f))*k + 0.9375f;
}
else {
return 7.5625f*(k -= (2.625f/2.75f))*k + 0.984375f;
}
}
public static float InOut (float k) {
if (k < 0.5f) return In(k*2f)*0.5f;
return Out(k*2f - 1f)*0.5f + 0.5f;
}
};
}
@Fonserbc
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@tenpn
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tenpn commented Dec 26, 2014

I think, strictly, you should include the MIT license header, since this could be considered a "substantial portion" of the original source http://opensource.org/licenses/MIT
Also makes it easier, if it's licensed, for me to use it in commercial software.

@Fonserbc
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Right!

@nabeelsaleem
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That's great can I post it on my blog?http://goo.gl/gaVTFD
Or is it commercially available?

@renatoi
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renatoi commented Aug 16, 2017

You should replace all float comparisons with Mathf.Approximately(float a, float b) https://docs.unity3d.com/ScriptReference/Mathf.Approximately.html

@Varollo
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Varollo commented Dec 17, 2019

How do I use these functions? What is k?

@Fonserbc
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How do I use these functions? What is k?

These are easing functions.

They transform a value k that is between 0 and 1, into another value that also lays between the range [0, 1] (most of the time).
They are used to transform a linearly increasing value (k) into a "eased" in-or-out value.
Check https://easings.net/ to visualize these functions.

@InitialXKO
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@Fonserbc
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No, check the script header.
This was adapted from https://github.com/sole/tween.js

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