public void Update()
{
// when the monster moves to the target position,
// we need to start to move to the next position again and again.
if (transform.position == new Vector3(targetPosition.x, targetPosition.y, 0))
{
// Remove the cost of tile on the start position
toggleCostOfTile(toPosition(currentPosition), false);
// Add the cost of tile on the target position
toggleCostOfTile(toPosition(targetPosition), true);
// Notify the player through notification system that the monster now in a new position.
NotificationSystem.publish(new MonsterMoveEvent(this, toPosition(currentPosition), toPosition(targetPosition)));
// Now the arrived target position becomes the start position for the next move.
currentPosition = targetPosition;
// Retrive the target position for the next move.
targetPosition = movingArea.getNextRandomPosition(transform.position);
}
float distance = Vector2.Distance(transform.position, targetPosition);
float duration = Time.time - startTime;
float distCovered = duration * speed;
transform.position = Vector2.Lerp(transform.position, targetPosition, distCovered / distance);
startTime = startTime + duration;
}