1. override
Matrix4 lerp(double t)

Returns the value this variable has at the given animation clock value.

Source 

@override
Matrix4 lerp(double t) {
  // TODO(abarth): We should use [Matrix4.decompose] and animate the
  // decomposed parameters instead of just animating the translation.
  Vector3 beginT = begin.getTranslation();
  Vector3 endT = end.getTranslation();
  Vector3 lerpT = beginT*(1.0-t) + endT*t;
  return new Matrix4.identity()..translate(lerpT);
}