public void ThinkAboutNextAction()
{
if (actionToDo != NONE)
{
return;
}
player = AIplayer.DummyPlayer;
visited[player.Location.X, player.Location.Y] = true;
BuildTree(BUILDTREEPERACTION);
// Decide next action
MeesGame.PlayerAction action = NONE;
foreach (NodeActionPair NAP in entryPoint.next)
{
if (NAP.Value.maxScore > entryPoint.maxScore && AIplayer.DummyPlayer.PossibleActions.Contains(action))
{
action = NAP.Key;
break;
}
}
actionToDo = action;
}
/// <summary>
/// Selects the node the player is on after performing the action that brings him to the given location.
/// </summary>
/// <param name="curNode">The current node.</param>
/// <param name="usedAction">The action performed.</param>
/// <param name="nextLocation">The location after performing the action.</param>
/// <returns></returns>
private Node goToNextNode(Node curNode, MeesGame.PlayerAction usedAction, Point nextLocation)
{
// Check if the node already has the next node in the list
foreach (NodeActionPair NAP in curNode.next)
{
if (NAP.Key == usedAction)
{
return(NAP.Value);
}
}
Node node;
// No node available, create a new one
if (nodeGrid[nextLocation.X, nextLocation.Y] == null)
{
node = new Node(nextLocation);
nodeGrid[nextLocation.X, nextLocation.Y] = node;
curNode.next.Add(usedAction, node);
return(node);
}
// The node is in the grid, use it and add it as neighbour
node = nodeGrid[nextLocation.X, nextLocation.Y];
curNode.next.Add(usedAction, node);
return(node);
}
/// <summary>
/// Helper method to get the reverse direction.
/// </summary>
/// <param name="action"></param>
/// <returns></returns>
private MeesGame.PlayerAction GetReverseAction(MeesGame.PlayerAction action)
{
switch (action)
{
case NORTH:
return(SOUTH);
case EAST:
return(WEST);
case SOUTH:
return(NORTH);
case WEST:
return(EAST);
default:
return(NONE);
}
}
/// <summary>
/// This function should be called at least once before checking the best possible move.
/// </summary>
public void BuildTree()
{
MeesGame.IPlayer dummy = player.Clone();
Point curLoc = dummy.Location;
int iterations = 0;
Node curNode = entryPoint;
nodeStack = new Stack <Node>();
nodeStack.Push(curNode);
MeesGame.PlayerAction lastAction = NONE;
while (iterations < MAXITERATIONS)
{
iterations += 1;
// pick a random action to perform
MeesGame.PlayerAction chosenAction = dummy.PossibleActions[GameEnvironment.Random.Next(dummy.PossibleActions.Count)];
if (chosenAction == NONE /* || (GetReverseAction(chosenAction) == lastAction)*/)
{
continue;
}
//perform action
dummy.PerformAction(chosenAction);
nodeStack.Push(curNode);
curNode = goToNextNode(curNode, chosenAction, dummy.Location);
curLoc = dummy.Location;
if (!visited[curLoc.X, curLoc.Y])
{
curNode.maxScore = getScore(curLoc);
break;
}
lastAction = chosenAction;
}
//max number of iterations reached, or broken out of the loop
updateScore();
}
/// <summary>
/// Make the AI pick the next action.
/// </summary>
public void UpdateNextAction()
{
AIplayer.NextAIAction = actionToDo;
actionToDo = NONE;
}
/// <summary>
/// The Q function receives a ILevelState s and a to be performed PlayerAction a.
/// It determines what the result is of this action and then updates the entry for (s, a) in the qValues library.
/// </summary>
/// <param name="s"></param>
/// <param name="a"></param>
private void Q(ILevelState s, MeesGame.PlayerAction a)
{
Tuple <ILevelState, MeesGame.PlayerAction> StateAndAction = new Tuple <ILevelState, MeesGame.PlayerAction>(s, a);
qValues[StateAndAction] = qValues[StateAndAction] + learningRate * ((double)GetResultOfAction(s, a) + discountFactor * EstimatedOptimalFutureValue(s, a) - qValues[StateAndAction]);
}
/// <summary>
/// This function estimates the best qValue that can be obtained by performing an action in the new ILevelState s' that is reached by performing PlayerAction a in ILevelState s.
/// </summary>
/// <param name="s"></param>
/// <param name="a"></param>
/// <returns></returns>
private double EstimatedOptimalFutureValue(ILevelState s, MeesGame.PlayerAction a)
{
return(0);
}
/// <summary>
/// Returns the score of the performed action a on the ILevelSTate s.
/// </summary>
/// <param name="s"></param>
/// <param name="a"></param>
private int GetResultOfAction(ILevelState s, MeesGame.PlayerAction a)
{
return(0);
}
