Simple Easing Functions for Unity

Super simple, fast and easy to use tweening functions for unity which incorporates optimised Robert Penner's equations.

Functions taken from https://github.com/sole/tween.js/blob/master/src/Tween.js

and converted for unity by Fonserbc / https://gist.github.com/Fonserbc/3d31a25e87fdaa541ddf#file-easing-cs

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using UnityEngine;


 


/* 


 * Functions taken from Tween.js - Licensed under the MIT license


 * at https://github.com/sole/tween.js


 */


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);


  }  


 };


 


 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;


  }  


 };


}



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