bool BuildGraph(AIPlannerNode parent, ref List <AIPlannerNode> leaves, HashSet <AIPlannerIAction> actions, AIPlannerIState goalstate)
{
bool result = false;
foreach (var action in actions)
{
if (parent.state.Test(action.preConditions))
{
var state = (AIPlannerIState)parent.state.Clone();
state.Apply(action.effects);
var node = new AIPlannerNode(parent, parent.runningCost + action.cost, state, action);
if (state.Test(goalstate))
{
leaves.Add(node);
result = true;
}
else
{
var subset = new HashSet <AIPlannerIAction>(actions.Where(a => !a.Equals(action))); // remove this action from the list and look again
result = BuildGraph(node, ref leaves, subset, goalstate) || result;
}
}
}
return(result);
}
internal AIPlannerNode(AIPlannerNode parent, float runningCost, AIPlannerIState state, AIPlannerIAction action)
{
this.parent = parent;
this.runningCost = runningCost;
this.state = state;
this.action = action;
}
public Queue <AIPlannerIAction> Plan(HashSet <AIPlannerIAction> actions, AIPlannerIState worldstate, AIPlannerIState goalstate)
{
foreach (var a in actions)
{
a.Reset();
}
var usableActions = new HashSet <AIPlannerIAction>(actions); // not checking for valid yet
var valids = new List <string>();
foreach (var action in usableActions)
{
if (worldstate.Test(action.preConditions))
{
valids.Add(action.GetType().Name);
}
}
Debugger.Instance.Log <AIPlanner>("Valid Next Actions: " + String.Join(", ", valids.ToArray()), agent.gameObject);
var leaves = new List <AIPlannerNode>();
var root = new AIPlannerNode(null, 0f, worldstate, null);
if (!BuildGraph(root, ref leaves, usableActions, goalstate))
{
return(null); // no valid plans found
}
var cheapest = leaves.OrderBy(l => l.runningCost).First();
var ancestors = new List <AIPlannerIAction>();
while (cheapest != null)
{
if (cheapest.action != null)
{
ancestors.Insert(0, cheapest.action);
}
cheapest = cheapest.parent;
}
Debugger.Instance.Log <AIPlanner>("New Plan: " + String.Join(", ", ancestors.Select(a => a.GetType().Name).ToArray()), agent.gameObject);
return(new Queue <AIPlannerIAction>(ancestors));
}
