AnimationCurveUtils containing EaseIn and EaseOut functions. Public domain.

AnimationCurveUtils.cs

using UnityEngine;

public static class AnimationCurveUtils
{
    /// <summary>
    /// Creates an ease-in curve starting at timeStart, valueStart and ending at timeEnd,
    /// valueEnd.
    /// </summary>
    /// <param name="timeStart">The start time for the ease-in curve.</param>
    /// <param name="valueStart">The start value for the ease-in curve.</param>
    /// <param name="timeEnd">The end time for the ease-in curve.</param>
    /// <param name="valueEnd">The end value for the ease-in curve.</param>
    /// <returns>The ease-in curve generated from the specified values.</returns>
    public static AnimationCurve EaseIn(
        float timeStart, float valueStart, float timeEnd, float valueEnd)
        => new AnimationCurve(
            new Keyframe(timeStart, valueStart, inTangent: 0F, outTangent: 0F),
            new Keyframe(timeEnd, valueEnd, inTangent: 2F, outTangent: 2F));
    

    /// <summary>
    /// Creates an ease-out curve starting at timeStart, valueStart and ending at timeEnd,
    /// valueEnd.
    /// </summary>
    /// <param name="timeStart">The start time for the ease-out curve.</param>
    /// <param name="valueStart">The start value for the ease-out curve.</param>
    /// <param name="timeEnd">The end time for the ease-out curve.</param>
    /// <param name="valueEnd">The end value for the ease-out curve.</param>
    /// <returns>The ease-out curve generated from the specified values.</returns>
    public static AnimationCurve EaseOut(
        float timeStart, float valueStart, float timeEnd, float valueEnd)
        => new AnimationCurve(
            new Keyframe(timeStart, valueStart, inTangent: 2F, outTangent: 2F),
            new Keyframe(timeEnd, valueEnd, inTangent: 0F, outTangent: 0F));
}