main.dart

@override
double transformInternal(double t) {
  return troughTransform(elasticTransform(t));
}

double elasticTransform(double t) {
  final b = 12 / 27;
  return 1 + pow(2, -10 * t) * sin(((t - b / 4) * pi * 2) / b);
}

double troughTransform(double t) {
  return t * (1 - pow(e, pow(t, 12) * -5) * 4 / 9);
}