# 虚幻三消

* actor获取gamemode

```
Cast<AMatch3GameMode>(UGameplayStatics::GetGameMode(WorldContextObject))
这个WorldContextObject传AActor this就行了
```

* spawned actor获取spawn自己的actor

```
FActorSpawnParameters SpawnParams;
SpawnParams.Owner = this;
SpawnParams.Instigator = GetInstigator();
SpawnParams.SpawnCollisionHandlingOverride = ESpawnActorCollisionHandlingMethod::AlwaysSpawn;
// Tiles never rotate
FRotator SpawnRotation(0.0f, 0.0f, 0.0f);
// Spawn the tile.
ATile* const NewTile = World->SpawnActor<ATile>(TileToSpawn, SpawnLocation, SpawnRotation, SpawnParams);

然后spawned actor:
Grid = Cast<AGrid>(GetOwner());            
			
```

* GameInstance使用
	* 在Edit->Project Settings->Project->Maps & Modes里配置用自己的GameInstance类
	* GameInstance复写父类方法：
	
    ```
    
	// Called by the game at startup.
	void Init() override;

	// Called by the game as it shuts down.
	void Shutdown() override;
    ```
    在这两个函数实现中，先写自己的自定义实现，最后再调用父类实现Super::F()
    
    * GameInstance有个USaveGame作为成员变量，在其他地方不操作USaveGame，所有有关的操作都通过GameInstance直接或间接进行。
    	* 每个level的slotname都是关卡名 
    	*  有个【TMap FString, int32】记录一些东西，如分数，是否播放音乐(将int32转为bool)

	* GameInstance的init里面，注册了一些事件
	
    ```
    LoginChangedHandle = FCoreDelegates::OnUserLoginChangedEvent.AddUObject(this, &UMatch3GameInstance::OnLoginChanged);
	EnteringForegroundHandle = FCoreDelegates::ApplicationHasEnteredForegroundDelegate.AddUObject(this, &UMatch3GameInstance::OnEnteringForeground);
	EnteringBackgroundHandle = FCoreDelegates::ApplicationWillEnterBackgroundDelegate.AddUObject(this, &UMatch3GameInstance::OnEnteringBackground);
	ViewportHandle = FViewport::ViewportResizedEvent.AddUObject(this, &UMatch3GameInstance::OnViewportResize_Internal);

    ```
    
  * 获取GameInstance
  
  ```
   UGameInstance* GameplayStatics::GetGameInstance(const UObject* WorldContextObject);
  ```
 
 * 游戏的设置（是否播放声音、是否播放音乐等设置）也作为成员变量记录在GameInstance里，接着在对应情况时检查GameInstance的设置。
 
* 获取当前Level的名字

```
/**
	* Get the name of the currently-open level.
	*
	* @param bRemovePrefixString	remove any streaming- or editor- added prefixes from the level name.
	*/
	UFUNCTION(BlueprintCallable, meta = (WorldContext = "WorldContextObject", AdvancedDisplay = "1"), Category = "Game")
	static FString GameplayStatics::GetCurrentLevelName(const UObject* WorldContextObject, bool bRemovePrefixString = true);
```

* 棋盘生成算法

以当前Actor为中心，左下角为0
```
FVector AGrid::GetLocationFromGridAddress(int32 GridAddress) const
{
	FVector Center = GetActorLocation();
	FVector OutLocation = FVector(-(GridWidth * 0.5f) * TileSize.X + (TileSize.X * 0.5f), 0.0f, -(GridHeight * 0.5f) * TileSize.Y + (TileSize.Y * 0.5f));
	check(GridWidth > 0);
	OutLocation.X += TileSize.X * (float)(GridAddress % GridWidth);
	OutLocation.Z += TileSize.Y * (float)(GridAddress / GridWidth);
	OutLocation += Center;

	return OutLocation;
}
```

* GameMode
	* 重启当前关卡

	```
    
	FName LevelName(*UGameplayStatics::GetCurrentLevelName(this, true));
	UGameplayStatics::OpenLevel(this, LevelName);
    ```

	* 实现UserWidget的切换

	```
    void AMatch3GameMode::ChangeMenuWidget(TSubclassOf<UUserWidget> NewWidgetClass)
{
	if (CurrentWidget)
	{
		CurrentWidget->RemoveFromViewport();
		CurrentWidget = nullptr;
	}
	if (NewWidgetClass)
	{
		if (AMatch3PlayerController* PC = Cast<AMatch3PlayerController>(UMatch3BlueprintFunctionLibrary::GetLocalPlayerController(this)))
		{
			CurrentWidget = CreateWidget<UUserWidget>(PC, NewWidgetClass);
			if (CurrentWidget)
			{
				CurrentWidget->AddToViewport();
			}
		}
	}
    ```
	* IsGameActive()

	```
bool AMatch3GameMode::IsGameActive() const
{
	// Game is active whenever time hasn't run out or the timer is paused.
	FTimerManager& WorldTimerManager = GetWorldTimerManager();
	return (WorldTimerManager.IsTimerActive(GameOverTimer) || WorldTimerManager.IsTimerPaused(GameOverTimer));
}
	```

	* GetRemainingTime

	```
GetWorldTimerManager().GetTimerRemaining(GameOverTimer)
	```

	* 给计时器加时间

	```
    重新设置下timer就好
    GetWorldTimerManager().SetTimer(GameOverTimer, this, &AMatch3GameMode::GameOver, StartingTimeValue + (ScoreAwardCount * Reward.TimeAwarded), false);
					
    ```
    
    * GameMode一般和PlayerController打交道

* PlayerController->IsLocalController()
* the network to uniquely identify a player:

```
PlayerController->PlayerState->GetUniqueId()->GetHexEncodedString()
```

* 交换宝石时那种位置移动的动画，通过节点Timeline在两个位置中lerp实现