[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：