Programming Manual

How your game application works with HyEngine. All new projects are generated with this basic structure.

classDiagram
  HyEngine <|-- YourGame
  class HyEngine{
    -HyInit initStruct
    ...
    +HyEngine(HyInit)
    ~HyEngine()
    +RunGame() int32
    #virtual OnUpdate() bool
  }
  class YourGame{
    -HyCamera2d * pCamera
    -MainMenu mainMenu
    -ILevel * pCurrentLevel
    -LevelOne LevelOne
    ...
    +YourGame(HyInit)
    ~YourGame()
    #override OnUpdate() bool
  }

main.cpp

1. Initializes a HyInit structure

2. Instantiate YourGame class, which derives from HyEngine

3. Invoke YourGame::RunGame() to start the main game loop

---

Use YourGame class constructor to initialize your game.

Override OnUpdate() to implement your game's main logic, such as updating the current level or handling menu navigation. OnUpdate() is invoked within Harmony's main game loop whenever a frame of game logic needs to happen.

Simple programs might only need to declare a few scene nodes and can implement all logic directly in OnUpdate(). More complex games will likely want to create separate classes to encapsulate different game states or levels.

Most code objects derive from HyEntity2d

The member variables declared in your main game class can encapsulate the flow or main aspects of the program. These are usually custom classes derived from HyEntity2d. (1)

1. HyEntity2d is a special scene node that can contain other scene nodes like sprites, text, and audio. It also serves as a way to logically group and update objects within the game world.
   

   classDiagram
       HyEntity2d <|-- MainMenu
       HyEntity2d <|-- ILevel
       ILevel <|-- LevelOne
       class HyEntity2d{
       +HyEntity2d()
       ~HyEntity2d()
       #virtual OnUpdate() void
       }
       class MainMenu{
       -HySprite2d background
       -HyText2d menuText
       ...
       +MainMenu()
       ~MainMenu()
       #override OnUpdate() void
       }
       class ILevel{
       -MainCharacter * pMainCharacter
       -LevelStuff levelStuff
       ...
       +ILevel()
       ~ILevel()
       #override OnUpdate() void
       }

Engine Utilities

The HyEngine class (1) provides public static methods to easily access engine functionality and information.

1. HyEngine public static methods:

   class HyEngine
   {
       static HyEngine * sm_pInstance;
       ...
   
   public:
       HyEngine(const HyInit &initStruct);
       ~HyEngine();
       ...
       static bool IsInitialized();
       static const HyInit &InitValues();
       static std::string DateTime();
       static uint32 NumWindows();
       static HyWindow &Window(uint32 uiWindowIndex = 0);
       static float DeltaTime();
       static double DeltaTimeD();
       static void LoadingStatus(uint32 &uiNumQueuedOut, uint32 &uiTotalOut);
       static void PauseGame(bool bPause);
       static HyInput &Input();
       static HyAudioCore &Audio();
       static HyDiagnostics &Diagnostics();
       static HyShaderHandle DefaultShaderHandle(HyType eType);
       static std::string DataDir();
       static HyTextureQuadHandle CreateTexture(std::string sFilePath, HyTextureInfo textureInfo);
       static HyAudioHandle CreateAudio(std::string sFilePath, bool bIsStreaming = false, int32 iInstanceLimit = 0, int32 iCategoryId = 0);
   };
   

• ㅤCameras & Windows
  How to manage your camera viewports and render windows.

  std::vector<HyCamera2d *> cameraList;
  for(uint32 i = 0; i < HyEngine::NumWindows(); ++i)
  {
      cameraList.push_back(HyEngine::Window(i).CreateCamera2d());
      glm::vec2 ptCenter(HyEngine::Window(i).GetWidthF(0.5f),
                         HyEngine::Window(i).GetHeightF(0.5f));
      ...
  }
  

• ㅤScene Management -> Item Nodes | Entities & Physics | User Interface
  The building blocks to make the game.

  case STATE_Spinning:
      m_SpinNode.rot.Offset((m_fSpinSpeed * HyEngine::DeltaTime()));
      m_fElapsedTime += HyEngine::DeltaTime();
      if(m_fElapsedTime >= 3.0f)
          m_eState = STATE_PrepStop;
      break;
  case STATE_PrepStop:
  ...
  

• ㅤInput Handling
  Utilize Input Maps and get player input from various devices.

  uint32 uiDPadFlags = 0;
  if(HyEngine::Input().IsActionDown(ARCADESTICK_Up))
      uiDPadFlags |= DPad_Up;
  if(HyEngine::Input().IsActionDown(ARCADESTICK_Down))
      uiDPadFlags |= DPad_Down;
  ...
  if(HyEngine::Input().IsActionReleased(DEBUGKEY_DumpAtlases))
      HyEngine::Diagnostics().DumpAtlasUsage();
  

• ㅤAudio System
  Manage how HyAudio2d audio cues are played back, categories, and settings.

  btnVolumeDown.SetText("VOLUME DOWN");
  btnVolumeDown.SetButtonClickedCallback(
    [](HyButton *pBtn)
    {
      float fVolume = HyEngine::Audio().GetGlobalVolume() - 0.05f;
      fVolume = HyMath::Clamp(fVolume, 0.0f, 1.0f);
      HyEngine::Audio().SetGlobalVolume(fVolume);
    });
  

• ㅤDiagnostics & Debugging
  Logging, performance profiling, and on-screen diagnostic overlays.

  HyEngine::Diagnostics().Init("Prefix", "MyText", 1);
  ...
  if(HyEngine::Input().IsActionReleased(DEBUGKEY_DiagFPS))
  {
      uint32 uiDiagFlags = HyEngine::Diagnostics().GetShowFlags();
      uiDiagFlags ^= HYDIAG_Fps;
      HyEngine::Diagnostics().Show(uiDiagFlags);
  }
  

• ㅤShaders
  Override built-in shaders on scene nodes to create impressive effects.

  pShader = HY_NEW HyShader(HYSHADERPROG_Primitive);
  pShader->SetSourceCode(szVERTEXSHADER_SRC, HYSHADER_Vertex);
  pShader->AddVertexAttribute("attrPos", HyShaderVariable::vec2);
  pShader->AddVertexAttribute("attrUV", HyShaderVariable::vec2);
  pShader->SetSourceCode(szFRAGMENTSHADER_SRC, HYSHADER_Fragment);
  pShader->Finalize();
  ...
  m_PrimitiveBox.SetShader(pShader);
  

• ㅤDirect Asset Loading
  Load raw images and audio files off disk using scene nodes.

  HyTexturedQuad2d *pBoxArt = nullptr;
  pBoxArt = HY_NEW HyTexturedQuad2d("C:/art.png", HyTextureInfo());
  pBoxArt->Load();
  
  m_AudioTrack.Init("C:/songs/track1.wav", true, 0, 0);
  m_AudioTrack.volume.Set(1.0f);
  m_AudioTrack.Play();
  m_AudioTrack.Load();