/// <summary> 构建树并返回所有计划 </summary>
/// <param name="_parent">父节点，不可为空</param>
/// <param name="_usableActions">所有可行行为</param>
/// <param name="_goal">目标计划</param>
/// <param name="_leaves">已找到的所有计划</param>
/// <returns>是否找到计划</returns>
private bool BuildGraph(GOAPNode _parent, List <GOAPAction> _usableActions, GOAPGoal _goal, int _depth, int _maxDepth, List <GOAPNode> _leaves)
{
if (_maxDepth >= 1 && _depth >= _maxDepth)
{
return(false);
}
foreach (GOAPAction action in _usableActions)
{
// 不允许出现两个连续的相同行为
if (_parent == null || action == _parent.action || !action.IsProceduralPrecondition(_parent.state))
{
continue;
}
if (InState(_parent.state, action.Preconditions))
{
// 造成效果影响当前状态
Dictionary <string, bool> currentState = PopulateState(_parent.state, action.Effects);
// 生成动作完成的节点链，成本累加
GOAPNode node = NodePool.Spawn(_parent, _parent.runningCost + action.cost, currentState, action);
// 如果当前状态能够达成目标
if (currentState.TryGetValue(_goal.Key, out bool value) && value.Equals(_goal.Value))
{
_leaves.Add(node);
}
else
{
BuildGraph(node, _usableActions, _goal, ++_depth, _maxDepth, _leaves);
}
}
}
return(_leaves.Count > 0);
}
/// <summary> 定制最优计划 </summary>
/// <param name="_agent">代理</param>
/// <param name="_availableActions">所有可用行为</param>
/// <param name="_currentStates">当前状态</param>
/// <param name="_goal">目标状态，想要达到的状态</param>
public void Plan(GOAPAction[] _availableActions,
Dictionary <string, bool> _currentStates, GOAPGoal _goal, int _maxDepth, ref Queue <GOAPAction> _plan)
{
if (_currentStates.TryGetValue(_goal.Key, out bool value) && value.Equals(_goal.Value))
{
return;
}
NodePool.Dispose();
// 所有可用的行为
usableActions.Clear();
foreach (var action in _availableActions)
{
if (action.IsUsable())
{
action.DynamicallyEvaluateCost();
usableActions.Add(action);
}
}
// 根节点
root = NodePool.Spawn(null, 0, _currentStates, null);
// 所有能达到目标的节点
leaves.Clear();
// 成本最低的计划节点
cheapestNode = null;
// 成本最低计划
_plan.Clear();
// 如果通过构建节点树找到了能够达成目标的计划
if (BuildGraph(root, usableActions, _goal, 0, _maxDepth, leaves))
{
Stack <GOAPAction> goapActionStack = Stack_Pool.Spawn();
foreach (GOAPNode leaf in leaves)
{
if (cheapestNode == null)
{
cheapestNode = leaf;
}
else if (cheapestNode.runningCost > leaf.runningCost)
{
cheapestNode = leaf;
}
}
// 向上遍历并添加行为到栈中，直至根节点，因为从后向前遍历
while (cheapestNode != null)
{
goapActionStack.Push(cheapestNode.action);
if (cheapestNode.parent.action != null)
{
cheapestNode = cheapestNode.parent;
}
else
{
break;
}
}
//goapActions = new Queue<Action>();
// 再将栈压入到队列中
while (goapActionStack.Count > 0)
{
_plan.Enqueue(goapActionStack.Pop());
}
Stack_Pool.Release(goapActionStack);
}
// 用完回收所有对象
DictionaryObjPool.Dispose();
}