Dalamud/Dalamud/Interface/Animation/EasingFunctions/InElastic.cs

using System;

namespace Dalamud.Interface.Animation.EasingFunctions
{
    /// <summary>
    /// Class providing an "InElastic" easing animation.
    /// </summary>
    public class InElastic : Easing
    {
        private const double Constant = (2 * Math.PI) / 3;

        /// <summary>
        /// Initializes a new instance of the <see cref="InElastic"/> class.
        /// </summary>
        /// <param name="duration">The duration of the animation.</param>
        public InElastic(TimeSpan duration)
            : base(duration)
        {
            // ignored
        }

        /// <inheritdoc/>
        public override void Update()
        {
            var p = this.Progress;
            this.Value = p == 0
                        ? 0
                        : p == 1
                            ? 1
                            : -Math.Pow(2, (10 * p) - 10) * Math.Sin(((p * 10) - 10.75) * Constant);
        }
    }
}