SpringSim class

A physically accurate mass-spring-damper simulation.

Produces three distinct behaviors based on the damping ratio ζ:

  • Under-damped (ζ < 1): oscillates before settling (wobbly/spring)
  • Critically damped (ζ = 1): fastest settle without oscillation
  • Over-damped (ζ > 1): slow, exponential approach to target

Usage:

final sim = SpringSim(from: 0.0, to: 1.0, stiffness: 180, damping: 12);
final pos = sim.position(0.5); // position at t=0.5 seconds
Inheritance

Constructors

SpringSim({required double from, required double to, double mass = 1.0, double stiffness = 100.0, double damping = 10.0, double initialVelocity = 0.0})

Properties

damping → double
Damping coefficient. Higher = less oscillation.
final
dampingRatio → double
Damping ratio ζ (zeta). < 1 = under, = 1 = critical, > 1 = over.
no setter
from → double
Starting position.
final
hashCode → int
The hash code for this object.
no setterinherited
id → String
Unique identifier for this simulator type.
no setteroverride
initialVelocity → double
Initial velocity (units/sec). Positive = moving toward target.
final
mass → double
Object mass (kg). Higher = slower response.
final
naturalFrequency → double
Natural angular frequency ω₀.
no setter
runtimeType → Type
A representation of the runtime type of the object.
no setterinherited
stiffness → double
Spring stiffness (N/m). Higher = faster snapping.
final
to → double
Target (rest) position.
final

Methods

isDone(double t) → bool
True when the simulation has effectively come to rest.
override
normalized(double t, {required double from, required double to}) → double
Normalizes position to 0.0, 1.0 based on from and to. Useful for driving AnimationController.value.
inherited
noSuchMethod(Invocation invocation) → dynamic
Invoked when a nonexistent method or property is accessed.
inherited
position(double t) → double
Position at time t (seconds).
override
sample({double durationSec = 2.0, int sampleHz = 60}) → List<double>
Samples the simulation at sampleHz for durationSec seconds.
inherited
settleDuration({double maxTime = 10.0, int resolution = 120}) → double
Returns the time (seconds) at which isDone first becomes true, sampled at resolution steps per second. Returns maxTime if never done.
inherited
toString() → String
A string representation of this object.
override
velocity(double t) → double
Velocity at time t (units/second).
override

Operators

operator ==(Object other) → bool
The equality operator.
inherited

Static Methods

gentle({double from = 0.0, double to = 1.0}) → SpringSim
Gentle, smooth approach — overlays, dialogs.
ios({double from = 0.0, double to = 1.0}) → SpringSim
iOS-style interactive spring — tight and responsive.
material({double from = 0.0, double to = 1.0}) → SpringSim
Material You emphasized spring.
wobbly({double from = 0.0, double to = 1.0}) → SpringSim
Wobbly — good for list item reveals.