NodeCanvas自定义图树 - NodeCanvas - 游戏开发

NodeCanvas 是一款很棒的插件，包含了行为树、对话树、状态机等数据结构，提供可视化的图形服务，依此我们可以扩展一种 FlowTree 的流式图。

# 思考

# FlowTree

FlowTree 是我想要实现的一种数据结构，即流程树结构；在流程树中的所有节点会根据检查条件选择适合的分支依次执行。这其实和官方提供的 DialogTree 对话树的逻辑是差不多的；但是在对话树基本节点是对话节点。

为了能够执行一些列操作，而这一些操作可能包含对话也可能只是纯粹的 Action，故而需要一种新的流程树形式。

从上图中可以看出，我们可以不再依赖于对话节点，我们可以行为、条件、子图作为起始，也可以根据这些元素作为结尾任意的连接数据。

# 实现

目录结构

以上是一个基本树的目录组成结构，分别包括：

FlowTreeOwner 树持有者，继承自 MonoBehaviour
FlowTree 树数据，继承自 Graph
FTNode 基础节点数据，继承自 Node
FTConnection 基础连接数据，继承自 Connection

FlowTreeOwner

	public class FlowTreeOwner: GraphOwner<FlowTree>
	{
	}

FlowTree

	[CreateAssetMenu(menuName = "ParadoxNotion/NodeCanvas/Flow Tree Asset")]
	public class FlowTree : Graph
	{
	public override Type baseNodeType => typeof(FTNode);
	public override bool requiresAgent => false;
	public override bool requiresPrimeNode => true;
	public override bool isTree => true;
	public override PlanarDirection flowDirection => PlanarDirection.Horizontal;
	public override bool allowBlackboardOverrides => true;
	public override bool canAcceptVariableDrops => false;

	private float _intTime;
	private float _updateTime;

	private Status _rootStatus;

	private FTNode _currentNode;

	protected override void OnGraphStarted()
	{
	Debug.Log($"FlowTree {name} 启动");
	_currentNode = primeNode as FTNode;
	EnterNode(_currentNode != null ? _currentNode : (FTNode)primeNode);
	}

	protected override void OnGraphUpdate()
	{
	if ( _currentNode is IUpdatable ) {
	( _currentNode as IUpdatable )?.Update();
	}
	}

	protected override void OnGraphStoped()
	{
	_currentNode = null;

	}


	public void GoNext(int index = 0)
	{
	if (index < 0 \|\| index > _currentNode.outConnections.Count - 1)
	{
	Stop(true);

	return;
	}

	_currentNode.outConnections[index].status = Status.Success; //editor vis

	EnterNode(_currentNode.outConnections[index].targetNode as FTNode);
	}

	private void EnterNode(FTNode node)
	{
	_currentNode = node;
	_currentNode.Reset(false);
	if (_currentNode.Execute(agent, blackboard) == Status.Error)
	{
	Stop(false);
	}
	}
	}

FTNode

	public abstract class FTNode : Node
	{
	public override int maxInConnections => -1;
	public override int maxOutConnections => 1;
	public override Type outConnectionType => typeof(FTConnection);
	public override bool allowAsPrime => true;
	public override bool canSelfConnect => false;
	public override Alignment2x2 commentsAlignment => Alignment2x2.Right;
	public override Alignment2x2 iconAlignment => Alignment2x2.Right;

	/// <summary>
	/// 流程树
	/// </summary>
	protected FlowTree FlowTree => (FlowTree)graph;


	#if UNITY_EDITOR
	protected override void OnNodeInspectorGUI()
	{
	base.OnNodeInspectorGUI();
	}

	protected override UnityEditor.GenericMenu OnContextMenu(UnityEditor.GenericMenu menu)
	{
	menu.AddItem(new GUIContent("Breakpoint"), isBreakpoint, () => { isBreakpoint = !isBreakpoint; });
	return menu;
	}
	#endif
	}

FTConnection

	public class FTConnection:Connection
	{

	}

# 树步进和条件

有了数据结构还不行，我们还需要让数据按我们期望的方式流转起来，其实也就是我们需要告诉我们的树何时应该执行下一步。

树步进

	public void GoNext(int index = 0)
	{
	if (index < 0 \|\| index > _currentNode.outConnections.Count - 1)
	{
	Stop(true);

	return;
	}

	_currentNode.outConnections[index].status = Status.Success; //editor vis

	EnterNode(_currentNode.outConnections[index].targetNode as FTNode);
	}

	private void EnterNode(FTNode node)
	{
	_currentNode = node;
	_currentNode.Reset(false);
	if (_currentNode.Execute(agent, blackboard) == Status.Error)
	{
	Stop(false);
	}
	}

在 FlowTree 中有这样一个方法用于控制树步进，传入一个 index 代表选择的链接分支索引，用于进入下一个节点，如果节点返回失败则停止图，如果成功则进入下一个。

我们需要在所有需要进入下一个节点的地方调用 GoNext

例如当 Action 节点执行完时:

	void OnActionEnd(bool success) {

	if ( success ) {
	status = Status.Success;
	FlowTree.GoNext();
	return;
	}

	status = Status.Failure;
	FlowTree.Stop(false);
	}

例如当条件节点执行完时：

	protected override Status OnExecute(Component agent, IBlackboard bb)
	{
	if (outConnections.Count == 0)
	{
	return Error("There are no connections on the Dialogue Condition Node");
	}

	if (Condition == null)
	{
	return Error("There is no Conidition on the Dialoge Condition Node");
	}

	var isSuccess = Condition.CheckOnce(agent.transform, graphBlackboard);
	status = isSuccess ? Status.Success : Status.Failure;
	FlowTree.GoNext(status== Status.Success ? 0 : 1);
	return status;
	}

例如当子图执行完成时：

	void OnDLGFinished(bool success)
	{
	if (status == Status.Running)
	{
	status = success ? Status.Success : Status.Failure;

	FlowTree.GoNext(); // 让流程树继续
	}
	}

对于条件节点的处理，我们只需要提供一个 ConditionTask 用于处理即可：

ConditionNode

	[global::ParadoxNotion.Design.Icon("Condition")]
	[Color("b3ff7f")]
	public class ConditionNode : FTNode, ITaskAssignable<ConditionTask>
	{
	[SerializeField] private ConditionTask _condition;

	public ConditionTask Condition
	{
	get => _condition;
	set => _condition = value;
	}

	public Task task
	{
	get => Condition;
	set => Condition = (ConditionTask)value;
	}

	public override int maxOutConnections => 2;

	protected override Status OnExecute(Component agent, IBlackboard bb)
	{
	if (outConnections.Count == 0)
	{
	return Error("There are no connections on the Dialogue Condition Node");
	}

	if (Condition == null)
	{
	return Error("There is no Conidition on the Dialoge Condition Node");
	}

	var isSuccess = Condition.CheckOnce(agent.transform, graphBlackboard);
	status = isSuccess ? Status.Success : Status.Failure;
	FlowTree.GoNext(status== Status.Success ? 0 : 1);
	return status;
	}


	#if UNITY_EDITOR

	public override string GetConnectionInfo(int i)
	{
	return i == 0 ? "Then" : "Else";
	}

	#endif
	}

# 子图 / 外接图

对于子图来说，其实也是属于一个节点，所以本质是继承自 FTNode 。

FTNodeNested

	[Category("SubGraphs")]
	[Color("ffe4e1")]
	public abstract class FTNodeNested<T> : FTNode, IGraphAssignable<T> where T : Graph
	{
	[SerializeField] private List<BBMappingParameter> _variablesMap;

	public abstract BBParameter subGraphParameter { get; }

	public T currentInstance { get; set; }
	public abstract T subGraph { get; set; }

	Graph IGraphAssignable.currentInstance { get => currentInstance;
	set => currentInstance = (T)value;
	}

	Graph IGraphAssignable.subGraph { get => subGraph;
	set => subGraph = (T)value;
	}

	public Dictionary<Graph, Graph> instances { get; set; }

	public List<BBMappingParameter> variablesMap { get => _variablesMap;
	set => _variablesMap = value;
	}

	}

这里我们考虑使 FlowTree 中可以接入子图 DialogTree :

NestedDT

	[Name("Sub Dialogue")]
	[Description("Executes a sub Dialogue Tree. Returns Running while the sub Dialogue Tree is active. You can Finish the Dialogue Tree with the 'Finish' node and return Success or Failure.")]
	[global::ParadoxNotion.Design.Icon("Dialogue")]
	[DropReferenceType(typeof(DialogueTree))]
	public class NestedDT : FTNodeNested<DialogueTree>
	{
	[SerializeField, ExposeField, Name("Sub Tree")]
	private readonly BBParameter<DialogueTree> _nestedDialogueTree = null;

	public override DialogueTree subGraph
	{
	get => _nestedDialogueTree.value;
	set => _nestedDialogueTree.value = value;
	}

	public override BBParameter subGraphParameter => _nestedDialogueTree;

	//

	protected override Status OnExecute(Component agent, IBlackboard blackboard)
	{

	if (subGraph == null \|\| subGraph.primeNode == null)
	{
	return Status.Optional;
	}

	if (status == Status.Resting)
	{
	status = Status.Running;
	this.TryStartSubGraph(agent, OnDLGFinished);
	}

	if (status == Status.Running)
	{
	currentInstance.UpdateGraph(this.graph.deltaTime);
	}


	return status;
	}

	void OnDLGFinished(bool success)
	{
	if (status == Status.Running)
	{
	status = success ? Status.Success : Status.Failure;

	FlowTree.GoNext(); // 让流程树继续
	}
	}

	protected override void OnReset()
	{
	if (currentInstance != null)
	{
	currentInstance.Stop();
	}
	}
	}

行为树

# 思考

# FlowTree

# 实现

# 树步进和条件

# 子图 / 外接图

对象拷贝