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