r.Lumen.IrradianceFieldGather.RadianceCache.Stats

r.Lumen.IrradianceFieldGather.RadianceCache.Stats

#Overview

name: r.Lumen.IrradianceFieldGather.RadianceCache.Stats

This variable is created as a Console Variable (cvar).

• type: Var
• help: GPU print out Radiance Cache update stats.

It is referenced in 3 C++ source files.

#Summary

#Usage in the C++ source code

The purpose of r.Lumen.IrradianceFieldGather.RadianceCache.Stats is to control whether GPU statistics for the Radiance Cache update in Lumen’s Irradiance Field gathering process are printed out.

• This setting variable is part of the Lumen rendering system in Unreal Engine 5, specifically for the Irradiance Field gathering process.

• The Lumen subsystem within the Renderer module relies on this setting variable, as evidenced by its location in the LumenIrradianceFieldGather.cpp file.

• The value of this variable is set through the Unreal Engine console variable system, as indicated by the FAutoConsoleVariableRef declaration.

• This variable interacts directly with the GLumenIrradianceFieldStats variable, which is an integer used to store the actual value of the setting.

• Developers must be aware that enabling this variable will cause additional GPU statistics to be printed, which may impact performance if left enabled in a shipping build.

• Best practices when using this variable include:

  1. Using it primarily for debugging and performance analysis during development.
  2. Ensuring it’s disabled in shipping builds to avoid unnecessary overhead.
  3. Correlating the stats output with other Lumen settings to optimize rendering performance.

Regarding the associated variable GLumenIrradianceFieldStats:

• The purpose of GLumenIrradianceFieldStats is to store the actual integer value that determines whether Radiance Cache update stats should be printed.

• It is used within the LumenIrradianceFieldGather namespace, specifically in the SetupRadianceCacheInputs function.

• The value is set by the console variable system and is read when setting up the Radiance Cache inputs.

• This variable directly interacts with the r.Lumen.IrradianceFieldGather.RadianceCache.Stats console variable.

• Developers should be aware that this variable is used to pass the stats printing flag to the GPU shader code.

• Best practices for this variable include:

  1. Not modifying it directly in code, but rather using the console variable to change its value.
  2. Checking its value when debugging Lumen Irradiance Field gathering performance issues.
  3. Understanding that a non-zero value will enable stats printing, which may affect performance.

#References in C++ code

#Callsites

This variable is referenced in the following C++ source code:

#Loc: <Workspace>/Engine/Source/Runtime/Renderer/Private/Lumen/LumenIrradianceFieldGather.cpp:119

Scope: file

Source code excerpt:

int32 GLumenIrradianceFieldStats = 0;
FAutoConsoleVariableRef CVarLumenIrradianceFieldStats(
	TEXT("r.Lumen.IrradianceFieldGather.RadianceCache.Stats"),
	GLumenIrradianceFieldStats,
	TEXT("GPU print out Radiance Cache update stats."),
	ECVF_RenderThreadSafe
);

namespace LumenIrradianceFieldGather

#Associated Variable and Callsites

This variable is associated with another variable named GLumenIrradianceFieldStats. They share the same value. See the following C++ source code.

#Loc: <Workspace>/Engine/Source/Runtime/Renderer/Private/Lumen/LumenIrradianceFieldGather.cpp:117

Scope: file

Source code excerpt:

);

int32 GLumenIrradianceFieldStats = 0;
FAutoConsoleVariableRef CVarLumenIrradianceFieldStats(
	TEXT("r.Lumen.IrradianceFieldGather.RadianceCache.Stats"),
	GLumenIrradianceFieldStats,
	TEXT("GPU print out Radiance Cache update stats."),
	ECVF_RenderThreadSafe
);

namespace LumenIrradianceFieldGather
{

#Loc: <Workspace>/Engine/Source/Runtime/Renderer/Private/Lumen/LumenIrradianceFieldGather.cpp:143

Scope (from outer to inner):

file
namespace    LumenIrradianceFieldGather
function     LumenRadianceCache::FRadianceCacheInputs SetupRadianceCacheInputs

Source code excerpt:

		Parameters.OcclusionProbeResolution = GLumenIrradianceFieldProbeOcclusionResolution;
		Parameters.NumProbesToTraceBudget = GLumenIrradianceFieldNumProbesToTraceBudget;
		Parameters.RadianceCacheStats = GLumenIrradianceFieldStats;
		return Parameters;
	}
}

class FMarkRadianceProbesUsedByGBufferCS : public FGlobalShader
{