public Plan MakePlan(
World current, IGoal goal,
RefreshActionsCallback actionRefresh, RefreshWorldCallback worldRefresh)
{
worldRefresh(current);
PlanTree tree = new PlanTree(start: current);
while (!tree.IsEmpty())
{
// Select the endpoint of the easiest plan we have
// This is bredth-first, try "closest" for A*like
PlanTree.Node n = tree.PopCheapestLeaf();
if (goal.MeetsGoal(n.Expected))
{
Debug.Log("Plan found!");
return(tree.GetPlan(n));
}
IList <Step> actions = actionRefresh(n.Expected);
Debug.Log("Found " + actions.Count + " actions.");
foreach (Step a in actions)
{
tree.AddStep(n, a);
}
}
Debug.Log("No plan exists!");
return(new Plan(new List <Step>()));
}
private IEnumerator DoPlanningHelper()
{
currentlyPlanning = true;
// The amount of nodes we'll look at before we give up
const int MAX_NODES = 2048;
// The ammount of nodes we look at each frame
int nodesLookedAt = 0;
// Look at nodes until we find a path or give up
while (nodesLookedAt < MAX_NODES && !tree.IsEmpty())
{
// Get the next unexplored node
PlanTree.Node leaf = tree.PopCheapestLeaf();
nodesLookedAt++;
// Give the action a chance to update anything it needs
// Did we reach our goal?
if (leaf.state.Matches(goal))
{
plan = tree.GetPlan(leaf);
Debug.Log("Found plan of " + plan.Count +
" actions after looking at " + nodesLookedAt + " nodes!");
currentlyPlanning = false;
yield break;
}
// See if we can do any possible actions on this tree
foreach (Action act in possibleActions)
{
bool validAction = act.CheckPreconditions(leaf.state, goal);
if (validAction)
{
tree.AddAction(leaf, act);
}
}
// Wait for end of frame if that's what you're into
if (ticksPerFrame > 0 && (nodesLookedAt % ticksPerFrame == 0))
{
yield return(null);
}
}
plan = new Queue <Action>();
Debug.Log("Couldn't find a plan after looking at " + nodesLookedAt + " nodes.");
currentlyPlanning = false;
yield break;
}