raylib-cs/Examples/Easings.cs

using System;

namespace Examples;

public static class Easings
{
    // Linear Easing functions
    public static float EaseLinearNone(float t, float b, float c, float d)
    {
        return (c * t / d + b);
    }

    public static float EaseLinearIn(float t, float b, float c, float d)
    {
        return (c * t / d + b);
    }

    public static float EaseLinearOut(float t, float b, float c, float d)
    {
        return (c * t / d + b);
    }

    public static float EaseLinearInOut(float t, float b, float c, float d)
    {
        return (c * t / d + b);
    }

    // Sine Easing functions
    public static float EaseSineIn(float t, float b, float c, float d)
    {
        return (-c * MathF.Cos(t / d * (MathF.PI / 2)) + c + b);
    }

    public static float EaseSineOut(float t, float b, float c, float d)
    {
        return (c * MathF.Sin(t / d * (MathF.PI / 2)) + b);
    }

    public static float EaseSineInOut(float t, float b, float c, float d)
    {
        return (-c / 2 * (MathF.Cos(MathF.PI * t / d) - 1) + b);
    }

    // Circular Easing functions
    public static float EaseCircIn(float t, float b, float c, float d)
    {
        return (-c * (MathF.Sqrt(1 - (t /= d) * t) - 1) + b);
    }

    public static float EaseCircOut(float t, float b, float c, float d)
    {
        return (c * MathF.Sqrt(1 - (t = t / d - 1) * t) + b);
    }

    public static float EaseCircInOut(float t, float b, float c, float d)
    {
        if ((t /= d / 2) < 1)
        {
            return (-c / 2 * (MathF.Sqrt(1 - t * t) - 1) + b);
        }
        return (c / 2 * (MathF.Sqrt(1 - t * (t -= 2)) + 1) + b);
    }

    // Cubic Easing functions
    public static float EaseCubicIn(float t, float b, float c, float d)
    {
        return (c * (t /= d) * t * t + b);
    }

    public static float EaseCubicOut(float t, float b, float c, float d)
    {
        return (c * ((t = t / d - 1) * t * t + 1) + b);
    }

    public static float EaseCubicInOut(float t, float b, float c, float d)
    {
        if ((t /= d / 2) < 1)
        {
            return (c / 2 * t * t * t + b);
        }
        return (c / 2 * ((t -= 2) * t * t + 2) + b);
    }

    // Quadratic Easing functions
    public static float EaseQuadIn(float t, float b, float c, float d)
    {
        return (c * (t /= d) * t + b);
    }

    public static float EaseQuadOut(float t, float b, float c, float d)
    {
        return (-c * (t /= d) * (t - 2) + b);
    }

    public static float EaseQuadInOut(float t, float b, float c, float d)
    {
        if ((t /= d / 2) < 1)
        {
            return (((c / 2) * (t * t)) + b);
        }
        return (-c / 2 * (((t - 2) * (--t)) - 1) + b);
    }

    // Exponential Easing functions
    public static float EaseExpoIn(float t, float b, float c, float d)
    {
        return (t == 0) ? b : (c * MathF.Pow(2, 10 * (t / d - 1)) + b);
    }

    public static float EaseExpoOut(float t, float b, float c, float d)
    {
        return (t == d) ? (b + c) : (c * (-MathF.Pow(2, -10 * t / d) + 1) + b);
    }

    public static float EaseExpoInOut(float t, float b, float c, float d)
    {
        if (t == 0)
        {
            return b;
        }
        if (t == d)
        {
            return (b + c);
        }
        if ((t /= d / 2) < 1)
        {
            return (c / 2 * MathF.Pow(2, 10 * (t - 1)) + b);
        }
        return (c / 2 * (-MathF.Pow(2, -10 * --t) + 2) + b);
    }

    // Back Easing functions
    public static float EaseBackIn(float t, float b, float c, float d)
    {
        float s = 1.70158f;
        float postFix = t /= d;
        return (c * (postFix) * t * ((s + 1) * t - s) + b);
    }

    public static float EaseBackOut(float t, float b, float c, float d)
    {
        float s = 1.70158f;
        return (c * ((t = t / d - 1) * t * ((s + 1) * t + s) + 1) + b);
    }

    public static float EaseBackInOut(float t, float b, float c, float d)
    {
        float s = 1.70158f;
        if ((t /= d / 2) < 1)
        {
            return (c / 2 * (t * t * (((s *= (1.525f)) + 1) * t - s)) + b);
        }

        float postFix = t -= 2;
        return (c / 2 * ((postFix) * t * (((s *= (1.525f)) + 1) * t + s) + 2) + b);
    }

    // Bounce Easing functions
    public static float EaseBounceOut(float t, float b, float c, float d)
    {
        if ((t /= d) < (1 / 2.75f))
        {
            return (c * (7.5625f * t * t) + b);
        }
        else if (t < (2 / 2.75f))
        {
            float postFix = t -= (1.5f / 2.75f);
            return (c * (7.5625f * (postFix) * t + 0.75f) + b);
        }
        else if (t < (2.5 / 2.75))
        {
            float postFix = t -= (2.25f / 2.75f);
            return (c * (7.5625f * (postFix) * t + 0.9375f) + b);
        }
        else
        {
            float postFix = t -= (2.625f / 2.75f);
            return (c * (7.5625f * (postFix) * t + 0.984375f) + b);
        }
    }

    public static float EaseBounceIn(float t, float b, float c, float d)
    {
        return (c - EaseBounceOut(d - t, 0, c, d) + b);
    }

    public static float EaseBounceInOut(float t, float b, float c, float d)
    {
        if (t < d / 2)
        {
            return (EaseBounceIn(t * 2, 0, c, d) * 0.5f + b);
        }
        else
        {
            return (EaseBounceOut(t * 2 - d, 0, c, d) * 0.5f + c * 0.5f + b);
        }
    }

    // Elastic Easing functions
    public static float EaseElasticIn(float t, float b, float c, float d)
    {
        if (t == 0)
        {
            return b;
        }
        if ((t /= d) == 1)
        {
            return (b + c);
        }

        float p = d * 0.3f;
        float a = c;
        float s = p / 4;
        float postFix = a * MathF.Pow(2, 10 * (t -= 1));

        return (-(postFix * MathF.Sin((t * d - s) * (2 * MathF.PI) / p)) + b);
    }

    public static float EaseElasticOut(float t, float b, float c, float d)
    {
        if (t == 0)
        {
            return b;
        }
        if ((t /= d) == 1)
        {
            return (b + c);
        }

        float p = d * 0.3f;
        float a = c;
        float s = p / 4;

        return (a * MathF.Pow(2, -10 * t) * MathF.Sin((t * d - s) * (2 * MathF.PI) / p) + c + b);
    }

    public static float EaseElasticInOut(float t, float b, float c, float d)
    {
        if (t == 0)
        {
            return b;
        }
        if ((t /= d / 2) == 2)
        {
            return (b + c);
        }

        float p = d * (0.3f * 1.5f);
        float a = c;
        float s = p / 4;

        float postFix = 0f;
        if (t < 1)
        {
            postFix = a * MathF.Pow(2, 10 * (t -= 1));
            return -0.5f * (postFix * MathF.Sin((t * d - s) * (2 * MathF.PI) / p)) + b;
        }

        postFix = a * MathF.Pow(2, -10 * (t -= 1));

        return (postFix * MathF.Sin((t * d - s) * (2 * MathF.PI) / p) * 0.5f + c + b);
    }
}