CatmullRom.cs

static void CatmullRom(List<float3> input, List<float3> result) {
    result.Clear();
    if (input.Count <= 2) {
        foreach (var p in input) result.Add(p);
        return;
    }

    var count = input.Count;
    // first curve
    CatmullRom(input[0], input[0], input[1], input[2]);
    for (var i = 0; i + 3 < count; i++)
        CatmullRom(input[i], input[i + 1], input[i + 2], input[i + 3]);

    // last curve
    CatmullRom(input[count - 3], input[count - 2], input[count - 1], input[count - 1]);

    void CatmullRom(float3 p0, float3 p1, float3 p2, float3 p3) {
        var c0 = p1;
        var c1 = (-p0 + 6 * p1 + 1 * p2) * (1 / 12.0f);
        var c2 = (p1 + 6 * p2 - p3) * (1 / 12.0f);
        var c3 = p2;

        Bezier(c0, c1, c2, c3);
    }


    void Bezier(float3 p0, float3 p1, float3 p2, float3 p3) {
        const float segments = 12f;

        for (int i = 1; i <= segments; i++) {
            var t = i / segments;
            var p = EvaluateCubicBezier(p0, p1, p2, p3, t);
            result.Add(p);
        }
    }

    float3 EvaluateCubicBezier(float3 p0, float3 p1, float3 p2, float3 p3, float t) {
        t = math.clamp(t, 0f, 1f); // todo ?
        var tr = 1 - t;
        return tr * tr * tr * p0 + 3 * tr * tr * t * p1 + 3 * tr * t * t * p2 + t * t * t * p3;
    }
}