Structs to represent HSL and HSV colours in Unity.

HSLandHSV.cs

using UnityEngine;

/// <summary>
/// Represents a color with hue, saturation, and lightness.
/// </summary>
readonly struct HSL
{
    public Color Color => HSV.FromHSL(this).Color;

    public readonly float H;
    public readonly float S;
    public readonly float L;

    public HSL(float H, float S, float L)
    {
        this.H = H;
        this.S = S;
        this.L = L;
    }

    public static HSL FromColor(Color color)
    {
        var hsv = HSV.FromColor(color);
        return FromHSV(hsv);
    }

    public static HSL FromHSV(HSV hsv)
    {
        // https://en.wikipedia.org/wiki/HSL_and_HSV#HSV_to_HSL
        var H = hsv.H;
        var L = hsv.V * (1 - hsv.S / 2);
        var S = L > 0 && L < 1 ? (hsv.V - L) / Mathf.Min(L, 1 - L) : 0;
        return new HSL(H, S, L);
    }
}

/// <summary>
/// Represents a color with hue, saturation, and value.
/// </summary>
readonly struct HSV
{
    public Color Color => Color.HSVToRGB(H, S, V);

    public readonly float H;
    public readonly float S;
    public readonly float V;

    public HSV(float H, float S, float V)
    {
        this.H = H;
        this.S = S;
        this.V = V;
    }

    public static HSV FromColor(Color color)
    {
        Color.RGBToHSV(color, out var H, out var S, out var V);
        return new HSV(H, S, V);
    }

    public static HSV FromHSL(HSL hsl)
    {
        // https://en.wikipedia.org/wiki/HSL_and_HSV#HSL_to_HSV
        var H = hsl.H;
        var V = hsl.L + hsl.S * Mathf.Min(hsl.L, 1 - hsl.L);
        var S = V > 0 ? 2 * (1 - hsl.L / V) : 0;
        return new HSV(H, S, V);
    }
}