Point lerp(Point a, Point b, double t)

Linearly interpolate between two points.

If either point is null, this function interpolates from Point.origin.

Source 

static Point lerp(Point a, Point b, double t) {
  if (a == null && b == null)
    return null;
  if (a == null)
    return b * t;
  if (b == null)
    return a * (1.0 - t);
  return new Point(lerpDouble(a.x, b.x, t), lerpDouble(a.y, b.y, t));
}