/// <summary>
/// Apply the action's effects to the parent state.
/// </summary>
/// <param name="actionEffects">Current state</param>
/// <param name="parentState">State change</param>
private Dictionary <string, bool> PopulateState(Dictionary <string, bool> actionEffects, Dictionary <string, bool> parentState)
{
Dictionary <string, bool> state = GOAPPlannerHelper.GetFreeState();
state.Clear();
foreach (KeyValuePair <string, bool> s in actionEffects)
{
state.Add(s.Key, s.Value);
}
foreach (KeyValuePair <string, bool> change in parentState)
{
// If key exists in the current state, update the value.
if (state.ContainsKey(change.Key))
{
state[change.Key] = change.Value;
}
else
{
state.Add(change.Key, change.Value);
}
}
return(state);
}
/// <summary>
/// Creates a subset of the actions excluding the actionToRemove. Creates a new set.
/// </summary>
/// <param name="actions">Usuable actions</param>
/// <param name="actionToRemove">Action to exclude from this branch</param>
private HashSet <GOAPAction> ActionSubset(HashSet <GOAPAction> actions, GOAPAction actionToRemove)
{
HashSet <GOAPAction> subset = GOAPPlannerHelper.GetFreeActionSet();
foreach (GOAPAction action in actions)
{
if (!action.Equals(actionToRemove))
{
subset.Add(action);
}
}
return(subset);
}
/// <summary>
/// Builds the plan of actions. Returns true if at least one solution was found.
/// The possible paths are stored in the leaves list. Each leaf has a 'runningCost' value where the lowest cost will be the best action sequence.
/// </summary>
/// <param name="parent">Parent node</param>
/// <param name="leaves">List of nodes with possible paths</param>
/// <param name="usableActions">Actions available to the GOAPAgent</param>
/// <param name="goal">Goal that GOAPAgent is trying to achieve</param>
private bool BuildGraph(GOAPNode parent, List <GOAPNode> leaves, HashSet <GOAPAction> usableActions, KeyValuePair <string, bool> goal)
{
bool foundOne = false;
// Go through each action available at this node and see if we can use it here.
foreach (GOAPAction action in usableActions)
{
// If the parent state has the conditions for this action's preconditions, we can use it here.
if (InState(action.Preconditions, parent._state))
{
// Apply the action's effects to the parent state.
Dictionary <string, bool> currentState = PopulateState(parent._state, action.Effects);
GOAPNode node = GOAPPlannerHelper.GetFreeNode(parent, parent._runningCost + action.GetCost(), parent._weight + action.GetWeight(), currentState, action);
// If there's no match between child's precondition and parent's effects or child's precondition is empty.
if (parent._action != null && (action.Preconditions.Count == 0 || !CondRelation(action.Preconditions, parent._action.Effects)))
{
continue;
}
if (GoalInState(goal, currentState))
{
// There is a solution.
leaves.Add(node);
foundOne = true;
}
else
{
// Not at a solution yet, so we're testing all of the remaining actions and branching out the tree.
HashSet <GOAPAction> subset = ActionSubset(usableActions, action);
bool found = BuildGraph(node, leaves, subset, goal);
if (found)
{
foundOne = true;
}
}
}
}
return(foundOne);
}
/// <summary>
/// Plans what sequence of actions can fulfill the goal.
/// Returns null if a plan could not be found, or a list of the actions that must be performed, in order, to fulfill the goal.
/// </summary>
/// <param name="agent">GOAPAgent</param>
/// <param name="availableActions">Actions that can be performed</param>
/// <param name="worldState">Starting world state</param>
/// <param name="goal">Goal that GOAPAgent is trying to achieve</param>
/// <param name="AIAgent">Implementing class that provides our world data and listens to feedback on planning</param>
public Queue <GOAPAction> Plan(GameObject agent,
HashSet <GOAPAction> availableActions,
Dictionary <string, bool> worldState,
KeyValuePair <string, bool> goal,
IAIAgent AIAgent)
{
// Reset all of the actions that can be performed.
foreach (GOAPAction action in availableActions)
{
action.DoReset();
}
// Loops through the available actions and adds the ones that can be performed to a list.
HashSet <GOAPAction> usableActions = GOAPPlannerHelper.GetFreeActionSet();
foreach (GOAPAction action in availableActions)
{
// If the the action can be performed.
if (action.CheckProceduralPrecondition(agent, AIAgent.DataHolder))
{
usableActions.Add(action);
}
}
// Create a "tree" of actions that will lead to the wanted goal.
List <GOAPNode> leaves = new List <GOAPNode>();
GOAPNode start = GOAPPlannerHelper.GetFreeNode(null, 0, 0, worldState, null);
bool success = BuildGraph(start, leaves, usableActions, goal);
if (!success)
{
return(null);
}
// Find the cheapest plan of action out of each generated plan.
GOAPNode cheapest = null;
foreach (GOAPNode leaf in leaves)
{
if (cheapest == null)
{
cheapest = leaf;
}
else
{
if (leaf.BetterThen(cheapest))
{
cheapest = leaf;
}
}
}
// Get its node and work back through the parents.
List <GOAPAction> result = new List <GOAPAction>();
GOAPNode n = cheapest;
while (n != null)
{
if (n._action != null)
{
// Insert the action in the front.
result.Insert(0, n._action);
}
n = n._parent;
}
// Clean up after we're done.
GOAPPlannerHelper.Release();
// Create a final plan to follow.
Queue <GOAPAction> finalQueue = new Queue <GOAPAction>();
foreach (GOAPAction action in result)
{
finalQueue.Enqueue(action);
}
return(finalQueue);
}