getPoint method
Implementation
@override
Vector? getPoint(double t, [Vector? optionalTarget]) {
  final point = Vector3.zero();//optionalTarget;
  if(optionalTarget != null){
    point.setFrom(optionalTarget);
  }
  if ( t == 1 ) {
    point.setFrom(v2);
  } else {
    point.setFrom(v2).sub(v1);
    point.scale(t).add(v1);
  }
  return point;
}