MagneticSim class

Simulates a magnetic attraction force toward a target point.

The pull increases as the object approaches the target, producing a smooth snap-to behavior without oscillation.

Useful for: snap targets, docking, magnetic buttons, pull-to-refresh snap.

Usage:

final sim = MagneticSim(position0: 0.0, target: 1.0, strength: 50.0);
final pos = sim.position(0.5);
Inheritance

Constructors

MagneticSim({required double position0, required double target, double strength = 50.0, double restThreshold = 0.01})
const

Properties

hashCode → int
The hash code for this object.
no setterinherited
id → String
Unique identifier for this simulator type.
no setteroverride
position0 → double
Starting position.
final
restThreshold → double
Rest threshold — how close to target counts as "done".
final
runtimeType → Type
A representation of the runtime type of the object.
no setterinherited
strength → double
Strength of the magnetic field (higher = snaps faster).
final
target → double
Target (attraction point).
final

Methods

force(double t) → double
Attraction force magnitude at time t.
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

dock({required double position0, required double target}) → MagneticSim
Dock behavior — used for element snapping to grid/anchor points.
gentle({double position0 = 0.0, double target = 1.0}) → MagneticSim
Gentle pull — soft, gradual attraction.
snap({double position0 = 0.0, double target = 1.0}) → MagneticSim
Quick snap — strong field, fast locking.