// --------------------------
// Start is called before the first frame update
void Start()
{
navMeshAgent = this.gameObject.GetComponent <NavMeshAgent>();
navMeshAgent.autoBraking = false; // disable auto braking for continuous movement
this.monsterYellingText.gameObject.SetActive(false); // disable UI yelling text
// generate an HTN tree for this monster
rootNode = generateHTNtree();
// generate a World State
HTN_WorldState ws = new HTN_WorldState(false, false, false, false, false); // set all false initially, let the update function to update WorldState
this.worldState = ws;
// create a HTN planner
planner = new HTN_Planner(this, worldState);
}
/// <summary>
/// Function to generate a plan for a given root node of HTN tree
/// </summary>
/// <param name="rootNode"></param>
public void planning(HTN_node rootNode)
{
HTN_WorldState state = this.currentWorldState.clone(); // make a copy of the current state
ArrayList finalPlanList = new ArrayList();
Stack <HTN_node> tasksNodes = new Stack <HTN_node>();
// stack for store Method node for backtracking
Stack <ArrayList> backTrackingMethods = new Stack <ArrayList>(); // each list in this stack is a list of methods
// stack for store planList for backtracking
Stack <ArrayList> backTrackingPlan = new Stack <ArrayList>();
Stack <HTN_WorldState> states = new Stack <HTN_WorldState>(); // store the copy of states for backtracking
tasksNodes.Push(rootNode); // put the root node into the task stack
// while the stack is not empty
while (!(tasksNodes.Count == 0))
{
HTN_node taskNode = tasksNodes.Pop();
// if the node is a compound node
if (taskNode is HTN_CompoundNode)
{
ArrayList methods = ((HTN_CompoundNode)taskNode).findSatisfiedMethods(this.currentWorldState);
//HTN_MethodNode method = ((HTN_CompoundNode)taskNode).findSatisfiedMethod(this.currentWorldState);
HTN_MethodNode method = (HTN_MethodNode)methods[0];
methods.RemoveAt(0);
if (method != null)
{
// store the plan and the next method node for backtracking when needed
backTrackingPlan.Push(new ArrayList(finalPlanList)); // clone the current plan list
backTrackingMethods.Push(methods);
states.Push(state.clone());
// push the subtasks of this method into the list (push backward since we want the first subtask to be pop next)
for (int i = method.getChildren().Count - 1; i >= 0; i--)
{
tasksNodes.Push((HTN_node)method.getChildren()[i]);
}
}
else
{
// restore to the saved backtracking state
state = states.Pop();
finalPlanList = backTrackingPlan.Pop();
tasksNodes.Clear(); // empty the tasksNode stack
// pop a methods list
ArrayList btMethods = backTrackingMethods.Pop();
while (btMethods.Count == 0)
{
btMethods = backTrackingMethods.Pop();
}
// get the first method in that list
HTN_MethodNode btMethodNode = (HTN_MethodNode)btMethods[0];
btMethods.RemoveAt(0); // delete that method from the list
if (btMethods.Count > 0)
{
backTrackingMethods.Push(btMethods); // put the method list back
}
// push the subtasks of this method into the list (push backward since we want the first subtask to be pop next)
for (int i = btMethodNode.getChildren().Count - 1; i >= 0; i--)
{
tasksNodes.Push((HTN_node)btMethodNode.getChildren()[i]);
}
}
}
else // primative node
{
// if the precondition is met
if (((HTN_PrimitiveNode)taskNode).verifyPrecondition(state))
{
// apply the effect of this task on the world state
((HTN_PrimitiveNode)taskNode).applyTask(state);
finalPlanList.Add(taskNode); // add this taskNode to the plan list
// if this primitive task is the last in the stack, our planning is finish
if (tasksNodes.Count == 0)
{
break;
}
}
else
{
// restore to the saved backtracking state
state = states.Pop();
finalPlanList = backTrackingPlan.Pop();
tasksNodes.Clear(); // empty the tasksNode stack
// pop a methods list
ArrayList btMethods = backTrackingMethods.Pop();
while (btMethods.Count == 0)
{
btMethods = backTrackingMethods.Pop();
}
// get the first method in that list
HTN_MethodNode btMethodNode = (HTN_MethodNode)btMethods[0];
btMethods.RemoveAt(0); // delete that method from the list
if (btMethods.Count > 0)
{
backTrackingMethods.Push(btMethods); // put the method list back
}
// push the subtasks of this method into the list (push backward since we want the first subtask to be pop next)
for (int i = btMethodNode.getChildren().Count - 1; i >= 0; i--)
{
tasksNodes.Push((HTN_node)btMethodNode.getChildren()[i]);
}
}
}
}
this.plan = finalPlanList; // set the current plan to the final plan list
}
/// <summary>
/// Function to add child node to this node
/// </summary>
/// <param name="childNode"></param>
public void addChild(HTN_node childNode)
{
this.children.Add(childNode);
}