getPositionForIteration method
Returns an offset for the specified iteration.
For a given iteration, the offset should be unique.
Implementation
@override
Offset getPositionForIteration(int iteration, ScatterContext context) {
final double angle = iteration * _stepRadians;
final double x = a * math.cos(angle + _startRadians);
final double y = b * math.sin(angle + _startRadians);
return Offset(x, y);
}