File path:
Engine\Source\Runtime\Core\Private\Misc\CoreGlobals.cpp

Source:

IMPLEMENT_MODULE( FCoreModule, Core );


/*-----------------------------------------------------------------------------
    Global variables.
-----------------------------------------------------------------------------*/

CORE_API FFeedbackContext*	GWarn						= nullptr;		/* User interaction and non critical warnings */
FConfigCacheIni*				GConfig						= nullptr;		/* Configuration database cache */
ITransaction*				GUndo						= nullptr;		/* Transaction tracker, non-NULL when a transaction is in progress */
FOutputDeviceConsole*		GLogConsole					= nullptr;		/* Console log hook */
CORE_API FMalloc*			GMalloc						= nullptr;		/* Memory allocator */
CORE_API FMalloc**			GFixedMallocLocationPtr = nullptr;		/* Memory allocator pointer location when PLATFORM_USES_FIXED_GMalloc_CLASS is true */

class UPropertyWindowManager*	GPropertyWindowManager	= nullptr;		/* Manages and tracks property editing windows */

/** For building call stack text dump in guard/unguard mechanism. */
TCHAR GErrorHist[16384]	= TEXT("");

/** For building exception description text dump in guard/unguard mechanism. */
TCHAR GErrorExceptionDescription[4096] = TEXT( "" );

/** The error message, can be assertion message, ensure message or message from the fatal error. */
TCHAR GErrorMessage[4096] = TEXT( "" );


CORE_API const FText GYes	= LOCTEXT("Yes",	"Yes");
CORE_API const FText GNo	= LOCTEXT("No",		"No");
CORE_API const FText GTrue	= LOCTEXT("True",	"True");
CORE_API const FText GFalse	= LOCTEXT("False",	"False");
CORE_API const FText GNone	= LOCTEXT("None",	"None");

/** If true, this executable is able to run all games (which are loaded as DLL's) **/
#if UE_GAME || UE_SERVER
    // In monolithic builds, implemented by the IMPLEMENT_GAME_MODULE macro or by UE4Game module.
    #if !IS_MONOLITHIC
        bool GIsGameAgnosticExe = true;
    #endif
#else
    // In monolithic Editor builds, implemented by the IMPLEMENT_GAME_MODULE macro or by UE4Game module.
    #if !IS_MONOLITHIC || !UE_EDITOR
        // Otherwise only modular editors are game agnostic.
        #if IS_PROGRAM || IS_MONOLITHIC
            bool GIsGameAgnosticExe = false;
        #else
            bool GIsGameAgnosticExe = true;
        #endif
    #endif //!IS_MONOLITHIC || !UE_EDITOR
#endif

/** When saving out of the game, this override allows the game to load editor only properties **/
bool GForceLoadEditorOnly = false;

/** Name of the core package					**/
FName GLongCorePackageName(TEXT("/Script/Core"));
/** Name of the core package					**/
FName GLongCoreUObjectPackageName(TEXT("/Script/CoreUObject"));

/** Disable loading of objects not contained within script files; used during script compilation */
bool GVerifyObjectReferencesOnly = false;

/** when constructing objects, use the fast path on consoles... */
bool GFastPathUniqueNameGeneration = false;

/** allow AActor object to execute script in the editor from specific entry points, such as when running a construction script */
bool GAllowActorScriptExecutionInEditor = false;

/** Forces use of template names for newly instanced components in a CDO */
bool GCompilingBlueprint = false;

/** True if we're reconstructing blueprint instances. Should never be true on cooked builds */
bool GIsReconstructingBlueprintInstances = false;

/** True if actors and objects are being re-instanced. */
bool GIsReinstancing = false;

/**
 * If true, we are running an editor script that should not prompt any dialog modal. The default value of any model will be used.
 * This is used when running a Blutility or script like Python and we don't want an OK dialog to pop while the script is running.
 * Could be set for commandlet with -RUNNINGUNATTENDEDSCRIPT
 */
bool GIsRunningUnattendedScript = false;

#if WITH_ENGINE
bool					PRIVATE_GIsRunningCommandlet		= false;				/** Whether this executable is running a commandlet (custom command-line processing code) */
bool					PRIVATE_GAllowCommandletRendering	= false;				/** If true, initialise RHI and set up scene for rendering even when running a commandlet. */
bool					PRIVATE_GAllowCommandletAudio 		= false;				/** If true, allow audio even when running a commandlet. */
#endif	// WITH_ENGINE

#if WITH_EDITORONLY_DATA
bool					GIsEditor						= false;					/* Whether engine was launched for editing */
bool					GIsImportingT3D					= false;					/* Whether editor is importing T3D */
bool					GIsUCCMakeStandaloneHeaderGenerator = false;				/* Are we rebuilding script via the standalone header generator? */
bool					GIsTransacting					= false;					/* true if there is an undo/redo operation in progress. */
bool					GIntraFrameDebuggingGameThread	= false;					/* Indicates that the game thread is currently paused deep in a call stack; do not process any game thread tasks */
bool					GFirstFrameIntraFrameDebugging	= false;					/* Indicates that we're currently processing the first frame of intra-frame debugging */
#elif USING_CODE_ANALYSIS
// These are always false during 'non-editor code analysis', just like they would be when #defined.
bool					GIsEditor						= false;
bool					GIsUCCMakeStandaloneHeaderGenerator = false;
bool					GIntraFrameDebuggingGameThread	= false;
bool					GFirstFrameIntraFrameDebugging	= false;
#endif // !WITH_EDITORONLY_DATA

bool					GEdSelectionLock				= false;					/* Are selections locked? (you can't select/deselect additional actors) */
bool					GIsClient						= false;					/* Whether engine was launched as a client */
bool					GIsServer						= false;					/* Whether engine was launched as a server, true if GIsClient */
bool					GIsCriticalError				= false;					/* An appError() has occured */
bool					GIsGuarded						= false;					/* Whether execution is happening within main()/WinMain()'s try/catch handler */
TSAN_ATOMIC(bool)		GIsRunning(false);											/* Whether execution is happening within MainLoop() */
bool					GIsDuplicatingClassForReinstancing = false;					/* Whether we are currently using SDO on a UClass or CDO for live reinstancing */
/** This specifies whether the engine was launched as a build machine process								*/
bool					GIsBuildMachine					= false;
/** This determines if we should output any log text.  If Yes then no log text should be emitted.			*/
bool					GIsSilent						= false;
bool					GIsSlowTask						= false;					/* Whether there is a slow task in progress */
bool					GSlowTaskOccurred				= false;					/* Whether a slow task began last tick*/
bool					GIsRequestingExit				= false;					/* Indicates that MainLoop() should be exited at the end of the current iteration */
/** Archive for serializing arbitrary data to and from memory												*/
bool					GAreScreenMessagesEnabled		= true;						/* Whether onscreen warnings/messages are enabled */
bool					GScreenMessagesRestoreState		= false;					/* Used to restore state after a screenshot */
int32					GIsDumpingMovie					= 0;						/* Whether we are dumping screenshots (!= 0), exposed as console variable r.DumpingMovie */
bool					GIsHighResScreenshot			= false;					/* Whether we're capturing a high resolution shot */
uint32					GScreenshotResolutionX			= 0;						/* X Resolution for high res shots */
uint32					GScreenshotResolutionY			= 0;						/* Y Resolution for high res shots */
uint64					GMakeCacheIDIndex				= 0;						/* Cache ID */

FString				GEngineIni;													/* Engine ini filename */

/** Editor ini file locations - stored per engine version (shared across all projects). Migrated between versions on first run. */
FString				GEditorIni;													/* Editor ini filename */
FString				GEditorKeyBindingsIni;										/* Editor Key Bindings ini file */
FString				GEditorLayoutIni;											/* Editor UI Layout ini filename */
FString				GEditorSettingsIni;											/* Editor Settings ini filename */

/** Editor per-project ini files - stored per project. */
FString				GEditorPerProjectIni;										/* Editor User Settings ini filename */

FString				GCompatIni;
FString				GLightmassIni;												/* Lightmass settings ini filename */
FString				GScalabilityIni;											/* Scalability settings ini filename */
FString				GHardwareIni;												/* Hardware ini filename */
FString				GInputIni;													/* Input ini filename */
FString				GGameIni;													/* Game ini filename */
FString				GGameUserSettingsIni;										/* User Game Settings ini filename */

float					GNearClippingPlane				= 10.0f;				/* Near clipping plane */

bool					GExitPurge						= false;

FChunkedFixedUObjectArray* GCoreObjectArrayForDebugVisualizers = nullptr;
#if PLATFORM_UNIX
FNameEntry*** CORE_API GFNameTableForDebuggerVisualizers_MT = FName::GetNameTableForDebuggerVisualizers_MT();
FChunkedFixedUObjectArray*& CORE_API GObjectArrayForDebugVisualizers = GCoreObjectArrayForDebugVisualizers;
#endif

/** Game name, used for base game directory and ini among other things										*/
#if (!IS_MONOLITHIC && !IS_PROGRAM)
// In modular game builds, the game name will be set when the application launches
TCHAR					GInternalProjectName[64]					= TEXT("None");
#elif !IS_MONOLITHIC && IS_PROGRAM
// In non-monolithic programs builds, the game name will be set by the module, but not just yet, so we need to NOT initialize it!
TCHAR					GInternalProjectName[64];
#else
// For monolithic builds, the game name variable definition will be set by the IMPLEMENT_GAME_MODULE
// macro for the game's main game module.
#endif

// Foreign engine directory. This is required to projects built outside the engine root to reference their engine directory.
#if !IS_MONOLITHIC
IMPLEMENT_FOREIGN_ENGINE_DIR()
#endif

/** A function that does nothing. Allows for a default behavior for callback function pointers. */
static void appNoop()
{
}

/** Exec handler for game debugging tool, allowing commands like "editactor", ...							*/
FExec*					GDebugToolExec					= NULL;
/** Whether we're currently in the async loading codepath or not											*/
static bool IsAsyncLoadingCoreInternal()
{
    // No Async loading in Core
    return false;
}
bool (*IsAsyncLoading)() = &IsAsyncLoadingCoreInternal;
void (*SuspendAsyncLoading)() = &appNoop;
void (*ResumeAsyncLoading)() = &appNoop;
bool (*IsAsyncLoadingSuspended)() = &IsAsyncLoadingCoreInternal;
bool (*IsAsyncLoadingMultithreaded)() = &IsAsyncLoadingCoreInternal;
void (*SuspendTextureStreamingRenderTasks)() = &appNoop;
void (*ResumeTextureStreamingRenderTasks)() = &appNoop;

/** Whether the editor is currently loading a package or not												*/
bool					GIsEditorLoadingPackage				= false;
/** Whether the cooker is currently loading a package or not												*/
bool					GIsCookerLoadingPackage = false;
/** Whether GWorld points to the play in editor world														*/
bool					GIsPlayInEditorWorld			= false;
/** Unique ID for multiple PIE instances running in one process */
int32					GPlayInEditorID					= -1;
/** Whether or not PIE was attempting to play from PlayerStart							*/
bool					GIsPIEUsingPlayerStart			= false;
/** true if the runtime needs textures to be powers of two													*/
bool					GPlatformNeedsPowerOfTwoTextures = false;
/** Time at which FPlatformTime::Seconds() was first initialized (before main)											*/
double					GStartTime						= FPlatformTime::InitTiming();
/** System time at engine init.																				*/
FString					GSystemStartTime;
/** Whether we are still in the initial loading proces.														*/
bool					GIsInitialLoad					= true;
/* Whether we are using the event driven loader */
bool					GEventDrivenLoaderEnabled = false;

/** Steadily increasing frame counter.																		*/
TSAN_ATOMIC(uint64)		GFrameCounter(0);
uint64					GLastGCFrame					= 0;
/** Incremented once per frame before the scene is being rendered. In split screen mode this is incremented once for all views (not for each view). */
uint32					GFrameNumber					= 1;
/** NEED TO RENAME, for RT version of GFrameTime use View.ViewFamily->FrameNumber or pass down from RT from GFrameTime). */
uint32					GFrameNumberRenderThread		= 1;
#if !(UE_BUILD_SHIPPING && WITH_EDITOR)
// We cannot count on this variable to be accurate in a shipped game, so make sure no code tries to use it
/** Whether we are the first instance of the game running.													*/
#if !PLATFORM_UNIX
bool					GIsFirstInstance				= true;
#endif
#endif
/** Threshold for a frame to be considered a hitch (in milliseconds). */
float GHitchThresholdMS = 60.0f;
/** Size to break up data into when saving compressed data													*/
int32					GSavingCompressionChunkSize		= SAVING_COMPRESSION_CHUNK_SIZE;
/** Thread ID of the main/game thread																		*/
uint32					GGameThreadId					= 0;
uint32					GRenderThreadId					= 0;
uint32					GSlateLoadingThreadId			= 0;
uint32					GAudioThreadId					= 0;
/** Has GGameThreadId been set yet?																			*/
bool					GIsGameThreadIdInitialized		= false;

/** Helper function to flush resource streaming.															*/
void					(*GFlushStreamingFunc)(void)	  = &appNoop;
/** Whether to emit begin/ end draw events.																	*/
bool					GEmitDrawEvents					= false;
/** Whether forward DrawEvents to the RHI or keep them only on the Commandlist. */
bool					GCommandListOnlyDrawEvents		= false;
/** Whether we want the rendering thread to be suspended, used e.g. for tracing.							*/
bool					GShouldSuspendRenderingThread	= false;
/** Determines what kind of trace should occur, NAME_None for none.											*/
FName					GCurrentTraceName				= NAME_None;
/** How to print the time in log output																		*/
ELogTimes::Type			GPrintLogTimes					= ELogTimes::None;
/** How to print the category in log output. */
bool					GPrintLogCategory = true;
/** How to print the verbosity in log output. */
bool					GPrintLogVerbosity = true;

#if USE_HITCH_DETECTION
bool				GHitchDetected = false;
#endif

/** Whether stats should emit named events for e.g. PIX.													*/
int32					GCycleStatsShouldEmitNamedEvents = 0;
/** Disables some warnings and minor features that would interrupt a demo presentation						*/
bool					GIsDemoMode						= false;
/** Whether or not a unit test is currently being run														*/
bool					GIsAutomationTesting					= false;
/** Whether or not messages are being pumped outside of the main loop										*/
bool					GPumpingMessagesOutsideOfMainLoop = false;

/** Enables various editor and HMD hacks that allow the experimental VR editor feature to work, perhaps at the expense of other systems */
bool					GEnableVREditorHacks = false;

bool CORE_API			GIsGPUCrashed = false;

bool GetEmitDrawEvents()
{
    return GEmitDrawEvents;
}

void CORE_API SetEmitDrawEvents(bool EmitDrawEvents)
{
    GEmitDrawEvents = EmitDrawEvents;
    GCommandListOnlyDrawEvents = !GEmitDrawEvents;
}

void CORE_API EnableEmitDrawEventsOnlyOnCommandlist()
{
    GCommandListOnlyDrawEvents = !GEmitDrawEvents;
    GEmitDrawEvents = true;
}

void ToggleGDebugPUCrashedFlag(const TArray<FString>& Args)
{
    GIsGPUCrashed = !GIsGPUCrashed;
    UE_LOG(LogCore, Log, TEXT("Gpu crashed flag forcibly set to: %i"), GIsGPUCrashed ? 1 : 0);
}

FAutoConsoleCommand ToggleDebugGPUCrashedCmd(
    TEXT("c.ToggleGPUCrashedFlagDbg"),
    TEXT("Forcibly toggles the 'GPU Crashed' flag for testing crash analytics."),
    FConsoleCommandWithArgsDelegate::CreateStatic(&ToggleGDebugPUCrashedFlag),
    ECVF_Cheat);

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