UE4的UE_LOG

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注意：
把log相关两个宏写到类中，并编译后，在输出日志的位置的Categories关键字过滤的位置看不到自己的标签是因为需要先运行一次，输出一些这个标签的log后，这个自定义的标签才会显示在这。


原文 https://wiki.unrealengine.com/Logs,_Printing_Messages_To_Yourself_During_Runtime#Log_an_FString
说明：本文为Wiki上的RAMA大神文章的大致翻译


游戏模式：
在游戏模式下，你需要在游戏的快捷方式后面加 -Log，才会在游戏中显示。

编辑器模式（Play In Editor）：
你可以在Output窗口中看到log信息。
如果想在游戏中看到，需要到Engin.ini中修改参数添加"GameCommandLine=-log，如果没有，则需要按~，输入-Log命令开启。


快速使用：
UE_LOG(LogTemp, Warning, TEXT("Your message"));
不用设置标签，简单快速。


设置拥有自己标签的Log：
在你的游戏头文件中加入：
//General LogDECLARE_LOG_CATEGORY_EXTERN(YourLog, Log, All);//Logging during game startupDECLARE_LOG_CATEGORY_EXTERN(YourInit, Log, All);//Logging for your AI systemDECLARE_LOG_CATEGORY_EXTERN(YourAI, Log, All);//Logging for Critical Errors that must always be addressedDECLARE_LOG_CATEGORY_EXTERN(YourCriticalErrors, Log, All);


这样输出的Log你就可以知道是哪个部分的，这也是UE_Log很有用的原因。


在你的游戏Cpp文件中：
//General LogDEFINE_LOG_CATEGORY(YourLog);//Logging during game startupDEFINE_LOG_CATEGORY(YourInit);//Logging for your AI systemDEFINE_LOG_CATEGORY(YourAI);//Logging for Critical Errors that must always be addressedDEFINE_LOG_CATEGORY(YourCriticalErrors);


Log格式：


Log Message
//"This is a message to yourself during runtime!"UE_LOG(YourLog,Warning,TEXT("This is a message to yourself during runtime!"));


Log an FString
%s strings are wanted as TCHAR* by Log, so use *FString()//"MyCharacter's Name is %s"UE_LOG(YourLog,Warning,TEXT("MyCharacter's Name is %s"), *MyCharacter->GetName() );


Log an Int
//"MyCharacter's Health is %d"UE_LOG(YourLog,Warning,TEXT("MyCharacter's Health is %d"), MyCharacter->Health );


Log a Float
//"MyCharacter's Health is %f"UE_LOG(YourLog,Warning,TEXT("MyCharacter's Health is %f"), MyCharacter->Health );


Log an FVector
//"MyCharacter's Location is %s"UE_LOG(YourLog,Warning,TEXT("MyCharacter's Location is %s"),     *MyCharacter->GetActorLocation().ToString());


Log an FName
//"MyCharacter's FName is %s"UE_LOG(YourLog,Warning,TEXT("MyCharacter's FName is %s"),     *MyCharacter->GetFName().ToString());


Log an FString,Int,Float
//"%s has health %d, which is %f percent of total health"UE_LOG(YourLog,Warning,TEXT("%s has health %d, which is %f percent of total health"),    *MyCharacter->GetName(), MyCharacter->Health, MyCharacter->HealthPercent);


Log的颜色设置：
//"this is Grey Text"UE_LOG(YourLog,Log,TEXT("This is grey text!"));//"this is Yellow Text"UE_LOG(YourLog,Warning,TEXT("This is yellow text!"));//"This is Red Text"UE_LOG(YourLog,Error,TEXT("This is red text!"));
可以看得出第二个参数是是用来控制颜色的。


传递客户端信息（网络模式）：
PlayerController->ClientMessage("Your Message");


命令行命令以及Engine.ini配置：


Log conventions (in the console, ini files, or environment variables)
[cat] = a category for the command to operate on, or 'global' for all categories.标签，没有设置就显示所有的Log[level] = verbosity level, one of: none, error, warning, display, log, verbose, all, default关卡，显示某某关卡的Log
At boot time, compiled in default is overridden by ini files setting, which is overridden by command line


Log console command usage
Log list - list all log categoriesLog list [string] - list all log categories containing a substringLog reset - reset all log categories to their boot-time defaultLog [cat] - toggle the display of the category [cat]Log [cat] off - disable display of the category [cat]Log [cat] on - resume display of the category [cat]Log [cat] [level] - set the verbosity level of the category [cat]Log [cat] break - toggle the debug break on display of the category [cat]


Log command line
-LogCmds=\"[arguments],[arguments]...\"           - applies a list of console commands at boot time-LogCmds=\"foo verbose, bar off\"         - turns on the foo category and turns off the bar category


Environment variables
Any command line option can be set via the environment variable UE-CmdLineArgs
set UE-CmdLineArgs=\"-LogCmds=foo verbose breakon, bar off\"


Config file
In DefaultEngine.ini or Engine.ini:
[Core.Log]global=[default verbosity for things not listed later][cat]=[level]foo=verbose break


Rama后面的一篇文章提供了显示代码行号、函数名称、类名等功能：
https://wiki.unrealengine.com/Logs,_Printing_the_Class_Name,_Function_Name,_Line_Number_of_your_Calling_Code!

原文链接