private static double GetSlopeX(double aT, double aA1, double aA2) => 3.0 * CubicBezier.A(aA1, aA2) * aT * aT + 2.0 * CubicBezier.B(aA1, aA2) * aT + CubicBezier.C(aA1);
private static double CalcBezierX(double aT, double aA1, double aA2) => ((CubicBezier.A(aA1, aA2) * aT + CubicBezier.B(aA1, aA2)) * aT + CubicBezier.C(aA1)) * aT;