[Flutter] Custom Curve

참고 https://www.funwithflutter.dev/creating-custom-animation-curves-in-flutter/

flutter가 제공하는 Curve도 많지만 Curve를 상속하는 새로운 class를 만들어서 사용할수 있다

class SineCurve extends Curve {
  final double count;

  SineCurve({this.count = 3});

  // t = x
  @override
  double transformInternal(double t) {
    var val = sin(count * 1.5 * pi * t) * 0.5 + 0.5;
    return val; //f(x)
  }
}

class SpringCurve extends Curve {
  const SpringCurve({
    this.a = 0.50,
    this.w = 10.4,
  });
  final double a;
  final double w;

  @override
  double transformInternal(double t) {
    return -(pow(e, -t / a) * cos(t * w)) + 1;
  }
}