[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 = ; 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 = ;
             for (int i = ; 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 = ; i < executionStatus.Length; ++i) {
                 executionStatus[i] = TaskStatus.Inactive;
             }
             currentChildIndex = ;
         }
     }
 }

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=,#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=,#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 = ;
     local a = function ()
         if (count <= ) then
             count = count + ;
             print("");
             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 = ;
     local a = function ()
         if (count <= ) then
             count = count + ;
             print("");
             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 = ;
     local a = function ()
         if (count <= ) then
             count = count + ;
             print("");
             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