private List <StateNode> GetAdjacentStates(StateNode parent, HashSet <GoapAction> availableActions, Dictionary <string, bool> goal)
{
List <StateNode> adjacent = new List <StateNode>();
// Go through each action available at this node
// and see if we can use it here
foreach (GoapAction action in availableActions)
{
// if the parent state has the conditions for this
// action's preconditions, we can use it here
if (InState(action.Preconditions, parent.State))
{
// Check if the Procedural Preconditions
// are also matched ( These are OR conditions )
if (action.CheckProceduralPreconditions())
{
// apply the action's effects to the parent state
Dictionary <string, bool> state = UpdatedState(parent.State, action.Effects);
// Create new Node State
StateNode node = new StateNode(parent, parent.RunningCost + action.GetCost(), state, action, goal);
// Add the new state to adjacent states
AddToListAndSort(adjacent, node);
}
}
}
return(adjacent);
}
private Plan FindPlan(HashSet <GoapAction> availableActions, Dictionary <string, bool> worldState, Dictionary <string, bool> goal, string agentName, string planName)
{
bool isPlanFound = false;
openListStates = new List <StateNode>();
closedListStates = new List <StateNode>();
adjacentStates = new List <StateNode>();
// start by adding the original state to the open list
AddToListAndSort(openListStates, new StateNode(null, 0, worldState, null, goal));
while (openListStates.Count > 0)
{
//TODO: Open List should be Sorted ( Ascending order by F )
// Get the square with the lowest F score
StateNode currentState = openListStates[0];
// add the current state to the closed list
closedListStates.Add(currentState);
// if we added the destination to the closed list, we've found a path
if (InState(goal, currentState.State))
{
isPlanFound = true;
break;
}
// Remove used action
availableActions.Remove(currentState.action);
// remove it from the open list
//openListStates.Remove(currentState);
openListStates.Clear();
// Retrieve all states next possible
adjacentStates = GetAdjacentStates(currentState, availableActions, goal);
foreach (StateNode state in adjacentStates)
{
// if this adjacent state is already in the closed list ignore it
if (closedListStates.Contains(state))
{
continue;
}
// if its not in the open list
if (!openListStates.Contains(state))
{
// compute its score, set the parent
AddToListAndSort(openListStates, state);
}
// if its already in the open list
else
{
// test if using the current G score make the states F score lower,
// if yes update the parent because it means its a better path
int index = openListStates.IndexOf(state);
StateNode oldState = openListStates[index];
if (state.StateCost < oldState.StateCost)
{
openListStates.RemoveAt(index);
AddToListAndSort(openListStates, state);
}
}
}
}
return(new Plan(closedListStates, isPlanFound, agentName, planName));
}
private void AddToListAndSort(List <StateNode> list, StateNode element)
{
list.Insert(0, element);
list.Sort();
}