[Unity插件]Lua行为树(十一)：组合节点Parallel

Parallel节点类似Sequence节点，不同在于Parallel会每帧执行所有的节点。当所有节点返回成功时返回成功，当其中一个节点返回失败时，返回失败并且结束所有的子节点运行。

例如说，给Sequence节点插入一个不断返回Running的行为节点，那么就会造成后面的子节点无法执行，而对于Parallel来说，是不会存在这种阻塞情况的。

Parallel.cs

namespace BehaviorDesigner.Runtime.Tasks
{
    [TaskDescription("Similar to the sequence task, the parallel task will run each child task until a child task returns failure. " +
                     "The difference is that the parallel task will run all of its children tasks simultaneously versus running each task one at a time. " +
                     "Like the sequence class, the parallel task will return success once all of its children tasks have return success. " +
                     "If one tasks returns failure the parallel task will end all of the child tasks and return failure.")]
    [HelpURL("http://www.opsive.com/assets/BehaviorDesigner/documentation.php?id=27")]
    [TaskIcon("{SkinColor}ParallelIcon.png")]
    public class Parallel : Composite
    {
        // The index of the child that is currently running or is about to run.
        private int currentChildIndex;
        // The task status of every child task.
        private TaskStatus[] executionStatus;

        public override void OnAwake()
        {
            // Create a new task status array that will hold the execution status of all of the children tasks.
            executionStatus = new TaskStatus[children.Count];
        }

        public override void OnChildStarted(int childIndex)
        {
            // One of the children has started to run. Increment the child index and set the current task status of that child to running.
            currentChildIndex++;
            executionStatus[childIndex] = TaskStatus.Running;
        }

        public override bool CanRunParallelChildren()
        {
            // This task can run parallel children.
            return true;
        }

        public override int CurrentChildIndex()
        {
            return currentChildIndex;
        }

        public override bool CanExecute()
        {
            // We can continue executing if we have more children that haven't been started yet.
            return currentChildIndex < children.Count;
        }

        public override void OnChildExecuted(int childIndex, TaskStatus childStatus)
        {
            // One of the children has finished running. Set the task status.
            executionStatus[childIndex] = childStatus;
        }

        public override TaskStatus OverrideStatus(TaskStatus status)
        {
            // Assume all of the children have finished executing. Loop through the execution status of every child and check to see if any tasks are currently running
            // or failed. If a task is still running then all of the children are not done executing and the parallel task should continue to return a task status of running.
            // If a task failed then return failure. The Behavior Manager will stop all of the children tasks. If no child task is running or has failed then the parallel
            // task succeeded and it will return success.
            bool childrenComplete = true;
            for (int i = 0; i < executionStatus.Length; ++i) {
                if (executionStatus[i] == TaskStatus.Running) {
                    childrenComplete = false;
                } else if (executionStatus[i] == TaskStatus.Failure) {
                    return TaskStatus.Failure;
                }
            }
            return (childrenComplete ? TaskStatus.Success : TaskStatus.Running);
        }

        public override void OnConditionalAbort(int childIndex)
        {
            // Start from the beginning on an abort
            currentChildIndex = 0;
            for (int i = 0; i < executionStatus.Length; ++i) {
                executionStatus[i] = TaskStatus.Inactive;
            }
        }

        public override void OnEnd()
        {
            // Reset the execution status and the child index back to their starting values.
            for (int i = 0; i < executionStatus.Length; ++i) {
                executionStatus[i] = TaskStatus.Inactive;
            }
            currentChildIndex = 0;
        }
    }
}

BTParallel.lua

BTParallel = BTComposite:New();

local this = BTParallel;
this.name = "BTParallel";

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

function this:OnUpdate()
    if (not self:HasChild()) then
        return BTTaskStatus.Failure;
    end

    for i=1,#self.childTasks do
        local childTask = self.childTasks[i];
        if (not self.executionStatus[i]) then --第一次执行
            self.executionStatus[i] = childTask:OnUpdate();
            if (self.executionStatus[i] == BTTaskStatus.Failure) then
                return BTTaskStatus.Failure;
            end
        elseif (self.executionStatus[i] == BTTaskStatus.Running) then --第二次以及以后执行
            self.executionStatus[i] = childTask:OnUpdate();
            if (self.executionStatus[i] == BTTaskStatus.Failure) then
                return BTTaskStatus.Failure;
            end
        end
    end

    local childrenComplete = true;
    for i=1,#self.executionStatus do
        if (self.executionStatus[i] == BTTaskStatus.Running) then
            childrenComplete = false;
            break;
        end
    end
    if (childrenComplete) then
        return BTTaskStatus.Success;
    else
        return BTTaskStatus.Running;
    end
end

测试如下：

1.BTSequence和BTParallel的对比

 BTSequence：

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 action = self:GetBTActionUniversal();
    local log = BTLog:New("This is log!!!");
    log.name = "log";

    self:SetStartTask(sequence);

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

function this:GetBTActionUniversal()
    local count = 1;
    local a = function ()
        if (count <= 3) then
            count = count + 1;
            print("22");
            return BTTaskStatus.Running;
        else
            return BTTaskStatus.Success;
        end
    end
    local universal = BTActionUniversal:New(nil, a);
    return universal;
end

BTParallel：

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 parallel = BTParallel:New();
    local action = self:GetBTActionUniversal();
    local log = BTLog:New("This is log!!!");
    log.name = "log";

    self:SetStartTask(parallel);

    parallel:AddChild(action);
    parallel:AddChild(log);
end

function this:GetBTActionUniversal()
    local count = 1;
    local a = function ()
        if (count <= 3) then
            count = count + 1;
            print("22");
            return BTTaskStatus.Running;
        else
            return BTTaskStatus.Success;
        end
    end
    local universal = BTActionUniversal:New(nil, a);
    return universal;
end

2.BTParallel中返回失败中断执行的情况

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 parallel = BTParallel:New();
    local action = self:GetBTActionUniversal();
    local action2 = self:GetBTActionUniversal2();

    self:SetStartTask(parallel);

    parallel:AddChild(action);
    parallel:AddChild(action2);
end

function this:GetBTActionUniversal()
    local count = 1;
    local a = function ()
        if (count <= 3) then
            count = count + 1;
            print("22");
            return BTTaskStatus.Running;
        else
            return BTTaskStatus.Success;
        end
    end
    local universal = BTActionUniversal:New(nil, a);
    return universal;
end

function this:GetBTActionUniversal2()
    local universal = BTActionUniversal:New(nil, function ()
        return BTTaskStatus.Failure;
    end);
    return universal;
end