kBezierSpringBuilder function

SpringDescription kBezierSpringBuilder({ required IndicatorMode mode, required double offset, required double actualTriggerOffset, required double velocity, })

Spring used by bezier curves. Creates a rubber band-like bouncing effect with gradual damping.

Implementation

physics.SpringDescription kBezierSpringBuilder({
  required IndicatorMode mode,
  required double offset,
  required double actualTriggerOffset,
  required double velocity,
}) {
  // Mass increases with pull distance, making larger pulls feel "heavier"
  final overscroll = (offset - actualTriggerOffset).clamp(0.0, 100.0);
  final double mass = 1.0 + overscroll / 100.0; // 1.0 ~ 2.0

  // High stiffness for fast, energetic bounces
  const double stiffness = 280.0;

  // Very low damping ratio (0.30) for highly pronounced bounces
  // Fast oscillations with large amplitude - snappy rubber band effect
  double dampingRatio = 0.30;
  if (velocity.abs() > 2000) {
    // Increase damping for very high velocity to prevent excessive bouncing
    dampingRatio += (velocity.abs() - 2000) / 10000 * 0.18;
    dampingRatio = dampingRatio.clamp(0.30, 0.58);
  }

  return physics.SpringDescription.withDampingRatio(
    mass: mass,
    stiffness: stiffness,
    ratio: dampingRatio,
  );
}