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DefaultEasingFunction.cs
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DefaultEasingFunction.cs
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// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
// See the LICENCE file in the repository root for full licence text.
using System;
namespace osu.Framework.Graphics.Transforms
{
/// <summary>
/// An easing function corresponding to one of the <see cref="Easing"/> types.
/// </summary>
public readonly struct DefaultEasingFunction : IEasingFunction
{
private const double elastic_const = 2 * Math.PI / .3;
private const double elastic_const2 = .3 / 4;
private const double back_const = 1.70158;
private const double back_const2 = back_const * 1.525;
private const double bounce_const = 1 / 2.75;
// constants used to fix expo and elastic curves to start/end at 0/1
private static readonly double expo_offset = Math.Pow(2, -10);
private static readonly double elastic_offset_full = Math.Pow(2, -11);
private static readonly double elastic_offset_half = Math.Pow(2, -10) * Math.Sin((.5 - elastic_const2) * elastic_const);
private static readonly double elastic_offset_quarter = Math.Pow(2, -10) * Math.Sin((.25 - elastic_const2) * elastic_const);
private static readonly double in_out_elastic_offset = Math.Pow(2, -10) * Math.Sin((1 - elastic_const2 * 1.5) * elastic_const / 1.5);
private readonly Easing easing;
/// <summary>
/// Creates a new <see cref="DefaultEasingFunction"/> for an <see cref="Easing"/>.
/// </summary>
/// <param name="easing">The <see cref="Easing"/> type.</param>
public DefaultEasingFunction(Easing easing)
{
this.easing = easing;
}
public double ApplyEasing(double time)
{
switch (easing)
{
default:
return time;
case Easing.In:
case Easing.InQuad:
return time * time;
case Easing.Out:
case Easing.OutQuad:
return time * (2 - time);
case Easing.InOutQuad:
if (time < .5) return time * time * 2;
return --time * time * -2 + 1;
case Easing.InCubic:
return time * time * time;
case Easing.OutCubic:
return --time * time * time + 1;
case Easing.InOutCubic:
if (time < .5) return time * time * time * 4;
return --time * time * time * 4 + 1;
case Easing.InQuart:
return time * time * time * time;
case Easing.OutQuart:
return 1 - --time * time * time * time;
case Easing.InOutQuart:
if (time < .5) return time * time * time * time * 8;
return --time * time * time * time * -8 + 1;
case Easing.InQuint:
return time * time * time * time * time;
case Easing.OutQuint:
return --time * time * time * time * time + 1;
case Easing.InOutQuint:
if (time < .5) return time * time * time * time * time * 16;
return --time * time * time * time * time * 16 + 1;
case Easing.InSine:
return 1 - Math.Cos(time * Math.PI * .5);
case Easing.OutSine:
return Math.Sin(time * Math.PI * .5);
case Easing.InOutSine:
return .5 - .5 * Math.Cos(Math.PI * time);
case Easing.InExpo:
return Math.Pow(2, 10 * (time - 1)) + expo_offset * (time - 1);
case Easing.OutExpo:
return -Math.Pow(2, -10 * time) + 1 + expo_offset * time;
case Easing.InOutExpo:
if (time < .5) return .5 * (Math.Pow(2, 20 * time - 10) + expo_offset * (2 * time - 1));
return 1 - .5 * (Math.Pow(2, -20 * time + 10) + expo_offset * (-2 * time + 1));
case Easing.InCirc:
return 1 - Math.Sqrt(1 - time * time);
case Easing.OutCirc:
return Math.Sqrt(1 - --time * time);
case Easing.InOutCirc:
if ((time *= 2) < 1) return .5 - .5 * Math.Sqrt(1 - time * time);
return .5 * Math.Sqrt(1 - (time -= 2) * time) + .5;
case Easing.InElastic:
return -Math.Pow(2, -10 + 10 * time) * Math.Sin((1 - elastic_const2 - time) * elastic_const) + elastic_offset_full * (1 - time);
case Easing.OutElastic:
return Math.Pow(2, -10 * time) * Math.Sin((time - elastic_const2) * elastic_const) + 1 - elastic_offset_full * time;
case Easing.OutElasticHalf:
return Math.Pow(2, -10 * time) * Math.Sin((.5 * time - elastic_const2) * elastic_const) + 1 - elastic_offset_half * time;
case Easing.OutElasticQuarter:
return Math.Pow(2, -10 * time) * Math.Sin((.25 * time - elastic_const2) * elastic_const) + 1 - elastic_offset_quarter * time;
case Easing.InOutElastic:
if ((time *= 2) < 1)
{
return -.5 * (Math.Pow(2, -10 + 10 * time) * Math.Sin((1 - elastic_const2 * 1.5 - time) * elastic_const / 1.5)
- in_out_elastic_offset * (1 - time));
}
return .5 * (Math.Pow(2, -10 * --time) * Math.Sin((time - elastic_const2 * 1.5) * elastic_const / 1.5)
- in_out_elastic_offset * time) + 1;
case Easing.InBack:
return time * time * ((back_const + 1) * time - back_const);
case Easing.OutBack:
return --time * time * ((back_const + 1) * time + back_const) + 1;
case Easing.InOutBack:
if ((time *= 2) < 1) return .5 * time * time * ((back_const2 + 1) * time - back_const2);
return .5 * ((time -= 2) * time * ((back_const2 + 1) * time + back_const2) + 2);
case Easing.InBounce:
time = 1 - time;
if (time < bounce_const)
return 1 - 7.5625 * time * time;
if (time < 2 * bounce_const)
return 1 - (7.5625 * (time -= 1.5 * bounce_const) * time + .75);
if (time < 2.5 * bounce_const)
return 1 - (7.5625 * (time -= 2.25 * bounce_const) * time + .9375);
return 1 - (7.5625 * (time -= 2.625 * bounce_const) * time + .984375);
case Easing.OutBounce:
if (time < bounce_const)
return 7.5625 * time * time;
if (time < 2 * bounce_const)
return 7.5625 * (time -= 1.5 * bounce_const) * time + .75;
if (time < 2.5 * bounce_const)
return 7.5625 * (time -= 2.25 * bounce_const) * time + .9375;
return 7.5625 * (time -= 2.625 * bounce_const) * time + .984375;
case Easing.InOutBounce:
if (time < .5) return .5 - .5 * new DefaultEasingFunction(Easing.OutBounce).ApplyEasing(1 - time * 2);
return new DefaultEasingFunction(Easing.OutBounce).ApplyEasing((time - .5) * 2) * .5 + .5;
case Easing.OutPow10:
return --time * Math.Pow(time, 10) + 1;
}
}
}
}