Setup system

• C++ implementation
• Blueprint implementation

C++

• Tutorial/Systems/TutorialMovementSystem.h:

  #pragma once
  
  #include "CoreMinimal.h"
  
  class USystemsWorld;
  
  UFUNCTION()
  void TUTORIAL_API TutorialMovementSystem(USystemsWorld& Systems);
  

• Tutorial/Systems/TutorialMovementSystem.cpp:

  #include "Tutorial/Systems/Persistent/TutorialMovementSystem.h"
  
  #include "Systems/Public/SystemsWorld.h"
  
  #include "Tutorial/Components/TutorialMovementComponent.h"
  
  void TutorialMovementSystem(USystemsWorld& Systems)
  {
      const auto DeltaTime = Systems.GetWorld()->GetDeltaSeconds();
  
      Systems.Query<UTutorialMovementComponent>().ForEach(
          [&](auto& QueryItem)
          {
              auto* Actor = QueryItem.Get<0>();
              auto* Movement = QueryItem.Get<1>();
              const auto Position = Actor->GetActorLocation();
              const auto Velocity = Movement->Value * DeltaTime;
  
              Actor->SetActorLocation(Position + Velocity);
          });
  }
  

Since this is a lambda system, we need to register it to FSystemsReflection. To do that you have to register it in your game module:

• Tutorial/Tutorial.h:

  #pragma once
  
  #include "CoreMinimal.h"
  
  #include "Modules/ModuleManager.h"
  
  class FTutorialModule : public IModuleInterface
  {
  public:
      virtual void StartupModule() override;
  
      virtual void ShutdownModule() override;
  };
  

• Tutorial/Tutorial.cpp:

  #include "Tutorial.h"
  
  #include "Systems/Public/SystemsReflection.h"
  
  #include "Tutorial/Systems/Persistent/TutorialMovementSystem.h"
  
  #define LOCTEXT_NAMESPACE "FTutorialModule"
  #define SYSTEMS_NAMESPACE "Tutorial"
  
  void FTutorialModule::StartupModule()
  {
      REGISTER_SYSTEM_FUNCTION(TutorialMovementSystem);
  }
  
  void FTutorialModule::ShutdownModule()
  {
      UNREGISTER_SYSTEM_FUNCTION(TutorialMovementSystem);
  }
  
  #undef LOCTEXT_NAMESPACE
  #undef SYSTEMS_NAMESPACE
  
  IMPLEMENT_GAME_MODULE(FTutorialModule, Tutorial);
  

Blueprint

1. Create new game object that inherits from Object:

   

   And name it BP_TutorialMovementQuery.

2. Add BP_TutorialMovement component and actor proeprties to tell over what systems world elements this query wants to iterate over.

   

   Here Actor is Actor and Movement is BP_TutorialMovement component.

3. Create new game object that inherits from UScriptableSystem:

   

   And name it BP_TutorialMovementSystem.

4. Override On Run event:

   

5. Create Query node and assign BP_TutorialMovementQuery class to it:

   

6. Create Lazy Iterate node:

   

7. Perform update on yielded object:

   

   Note that Movement::Value is multiplied by Delta Time provided by On Run event.

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