Circular easing in/out.
static double easeInOutCirc(double t) => t < 0.5 ? (1.0 - math.sqrt(1.0 - math.pow(2.0 * t, 2))) / 2.0 : (math.sqrt(1.0 - math.pow(-2.0 * t + 2.0, 2)) + 1.0) / 2.0;