说明

AI Task

在C++中生成随机点, 让NPC移动到随机生成位置

创建任务类型

• 创建蓝图任务类型的方法
  
  BT_STUCharacter
  

  点击 New Task
  

  

  
  

• C++
  

  -
  基类	BTTaskNode
  路径	AI/Tasks/
  	Public
  	STUNextLocationTask

  ShootThemUp: ShootThemUp.Build.cs
  

  修改头文件搜索路径
  

  Copy 1PublicIncludePaths.AddRange(new string[]
   2{
   3    "ShootThemUp/Public/Player",
   4    "ShootThemUp/Public/Components",
   5    "ShootThemUp/Public/Dev",
   6    "ShootThemUp/Public/Weapon",
   7    "ShootThemUp/Public/UI",
   8    "ShootThemUp/Public/Animations",
   9    "ShootThemUp/Public/Pickups",
  10    "ShootThemUp/Public/Weapon/Components",
  11    "ShootThemUp/Public/AI",
  12    "ShootThemUp/Public/AI/Tasks"             
  13});

  添加依赖模块GameplayTasks和NavigationSystem
  

  Copy 1PublicDependencyModuleNames.AddRange(new string[]
   2{
   3    "Core",
   4    "CoreUObject",
   5    "Engine",
   6    "InputCore",
   7    "Niagara",
   8    "PhysicsCore",
   9    "GameplayCameras",
  10    "GameplayTasks",
  11    "NavigationSystem"
  12});

实现任务: 在给定半径圆形范围内生成随机点并设置变量

• 添加构造函数
  
  ShootThemUp: AI/Tasks/STUNextLocationTask.h

public
  

  Copy1USTUNextLocationTask();

• 执行任务时调用ExecuteTask
  
  覆写
  
  ShootThemUp: AI/Tasks/STUNextLocationTask.h

public
  

  Copy1virtual EBTNodeResult::Type ExecuteTask(UBehaviorTreeComponent &OwnerComp, uint8 *NodeMemory) override;

• 添加属性
  
  半径和黑板变量
  
  ShootThemUp: AI/Tasks/STUNextLocationTask.h

protected
  

  Copy1UPROPERTY(EditAnywhere, BlueprintReadWrite)
  2float Radius = 1000.0f;
  3
  4UPROPERTY(EditAnywhere, BlueprintReadWrite)
  5FBlackboardKeySelector AimLocationKey;

• 在构造函数中设置任务节点名
  
  ShootThemUp: AI/Tasks/STUNextLocationTask.cpp
  

  Copy1USTUNextLocationTask::USTUNextLocationTask()
  2{
  3    NodeName = "Next Location";
  4}

• 生成随机点并写入黑板变量
  
  GetRandomReachablePointInRadius在游戏角色可以去到的nav mesh范围内计算随机点, 该函数在覆盖范围实现路径搜索算法
  

  如果找到该点, 游戏角色一定能从所处位置去到该点
  

  给出搜索中心点, 搜索半径, 存放点的变量
  

  ShootThemUp: AI/Tasks/STUNextLocationTask.cpp
  

  Copy 1#include "BehaviorTree/BlackboardComponent.h"
   2#include "AIController.h"
   3#include "NavigationSystem.h"
   4
   5EBTNodeResult::Type USTUNextLocationTask::ExecuteTask(UBehaviorTreeComponent &OwnerComp, uint8 *NodeMemory)
   6{
   7    const auto Controller = OwnerComp.GetAIOwner();
   8    const auto Blackboard = OwnerComp.GetBlackboardComponent();
   9    if (!Controller || !Blackboard) return EBTNodeResult::Failed;
  10
  11    const auto Pawn = Controller->GetPawn();
  12    if (!Pawn) return EBTNodeResult::Failed;
  13
  14    const auto NavSys = UNavigationSystemV1::GetCurrent(Pawn);
  15    if (!NavSys) return EBTNodeResult::Failed;
  16
  17    FNavLocation NavLocation;
  18    const auto Found = NavSys->GetRandomReachablePointInRadius(Pawn->GetActorLocation(), Radius, NavLocation);
  19    if (!Found) return EBTNodeResult::Failed;
  20
  21    Blackboard->SetValueAsVector(AimLocationKey.SelectedKeyName, NavLocation.Location);
  22    return EBTNodeResult::Succeeded;
  23}

查看

• 添加变量AimLocation
  
  BB_STUCharacter
  

• 更新行为树
  
  BT_STUCharacter
  
  > 生成随机点 > 等待两秒 > 去到随机点; 循环
  

  黑板变量绑定
  

  

  
  

  移动到随机点
  

  

  
  

• 移除上节在指定点往返逻辑
  
  BP_STUAIController
  

  

  
  

人为干预: 设置ExecuteTask返回Failed

BT_STUCharacter

• 添加任务: FinishedWithResult, 设置结果为Failed; 游戏角色停留在Wait节点
  

  

  
  

• 移除FinishedWithResult节点