[Unity插件]Lua行为树(八)：行为节点扩展

先看一下之前的行为节点是怎么设计的：

BTAction.lua

 BTAction = BTTask:New();

 local this = BTAction;
 this.taskType = BTTaskType.Action;

 function this:New()
     local o = {};
     setmetatable(o, self);
     self.__index = self;
     return o;
 end

BTLog.lua

 --[[
 参考BehaviorDesigner-Action-Log
 --]]
 BTLog = BTAction:New();

 local this = BTLog;
 this.name = "BTLog";

 function this:New(text)
     local o = {};
     setmetatable(o, self);
     self.__index = self;
     o.text = text;
     return o;
 end

 function this:OnUpdate()
     print(self.text);
     return BTTaskStatus.Success;
 end

由上可见，行为节点的具体逻辑都是放在OnUpdate中的，那么问题来了，如果想在OnUpdate前执行一段逻辑，OnUpdate后也执行一段逻辑，类似于状态机那样，那么就需要对行为节点进行扩展。

BTAction.lua

 BTAction = BTTask:New();

 local this = BTAction;
 this.taskType = BTTaskType.Action;
 this.isEnter = false;

 function this:New()
     local o = {};
     setmetatable(o, self);
     self.__index = self;
     return o;
 end

 function this:OnUpdate()
     local status;
     if (not self.isEnter) then
         self.isEnter = true;
         self:Enter();
     end
     if (self.isEnter) then
         status = self:Execute();
         if (status ~= BTTaskStatus.Running) then
             self:Exit();
             self.isEnter = false;
         end
     end
     return status;
 end

 function this:Enter()
     print("BTAction:Enter");
 end

 function this:Execute()
     print("BTAction:Execute");
     return BTTaskStatus.Success;
 end

 function this:Exit()
     print("BTAction:Exit");
 end

BTLog.lua

 --[[
 参考BehaviorDesigner-Action-Log
 --]]
 BTLog = BTAction:New();

 local this = BTLog;
 this.name = "BTLog";

 function this:New(text)
     local o = {};
     setmetatable(o, self);
     self.__index = self;
     o.text = text;
     return o;
 end

 function this:Enter()
     print(self.name .. ":Enter");
 end

 function this:Execute()
     print(self.text);
     return BTTaskStatus.Success;
 end

 function this:Exit()
     print(self.name .. ":Exit");
 end

TestBehaviorTree.lua

 TestBehaviorTree = BTBehaviorTree:New();

 local this = TestBehaviorTree;
 this.name = "TestBehaviorTree";

 function this:New()
     local o = {};
     setmetatable(o, self);
     self.__index = self;
     o:Init();
     return o;
 end

 function this:Init()
     local sequence = BTSequence:New();
     local log = BTLog:New("This is log!!!");
     local log2 = BTLog:New("This is log2!!!");
     log.name = "log";
     log2.name = "log2";

     self:SetStartTask(sequence);

     sequence:AddChild(log);
     sequence:AddChild(log2);
 end

打印如下：