bSupportsUInt64ImageAtomics

bSupportsUInt64ImageAtomics

#Overview

name: bSupportsUInt64ImageAtomics

The value of this variable can be defined or overridden in .ini config files. 5 .ini config files referencing this setting variable.

It is referenced in 4 C++ source files.

#Summary

#Usage in the C++ source code

The purpose of bSupportsUInt64ImageAtomics is to indicate whether a specific shader platform supports 64-bit unsigned integer atomic operations on images (textures) in GPU shaders.

This setting variable is primarily used in the RHI (Rendering Hardware Interface) module of Unreal Engine 5. It is part of the data-driven shader platform information system, which allows the engine to adapt its rendering capabilities based on the capabilities of the target hardware.

The value of this variable is set within the FGenericDataDrivenShaderPlatformInfo class, specifically in the ParseDataDrivenShaderInfo function. It is likely populated from a configuration file or hardware detection system during engine initialization.

bSupportsUInt64ImageAtomics interacts with other shader platform capability flags, such as bSupportsPrimitiveShaders, bSupportsNanite, and bSupportsLumenGI. These flags collectively define the feature set available for a particular shader platform.

Developers must be aware that this variable affects the availability of certain advanced rendering techniques that rely on 64-bit atomic operations on images. When this flag is false, alternative rendering methods may need to be implemented for platforms that don’t support this feature.

Best practices when using this variable include:

1. Always check its value before using 64-bit image atomic operations in shaders.
2. Provide fallback rendering paths for platforms where this feature is not supported.
3. Use the GetSupportsUInt64ImageAtomics() static function to query this capability rather than accessing the variable directly.
4. Consider this flag when designing cross-platform rendering techniques to ensure compatibility across different hardware capabilities.

#Setting Variables

#References In INI files

Location: <Workspace>/Engine/Config/Mac/DataDrivenPlatformInfo.ini:62, section: [ShaderPlatform METAL_SM5]

• INI Section: ShaderPlatform METAL_SM5
• Raw value: false
• Is Array: False

Location: <Workspace>/Engine/Config/Mac/DataDrivenPlatformInfo.ini:102, section: [ShaderPlatform METAL_SM6]

• INI Section: ShaderPlatform METAL_SM6
• Raw value: true
• Is Array: False

Location: <Workspace>/Engine/Config/VulkanPC/DataDrivenPlatformInfo.ini:61, section: [ShaderPlatform VULKAN_SM5]

• INI Section: ShaderPlatform VULKAN_SM5
• Raw value: false
• Is Array: False

Location: <Workspace>/Engine/Config/VulkanPC/DataDrivenPlatformInfo.ini:182, section: [ShaderPlatform VULKAN_SM6]

• INI Section: ShaderPlatform VULKAN_SM6
• Raw value: true
• Is Array: False

Location: <Workspace>/Engine/Config/Windows/DataDrivenPlatformInfo.ini:114, section: [ShaderPlatform PCD3D_SM6]

• INI Section: ShaderPlatform PCD3D_SM6
• Raw value: true
• Is Array: False

#References in C++ code

#Callsites

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

#Loc: <Workspace>/Engine/Source/Runtime/RHI/Private/DataDrivenShaderPlatformInfo.cpp:231

Scope (from outer to inner):

file
function     void FGenericDataDrivenShaderPlatformInfo::ParseDataDrivenShaderInfo

Source code excerpt:

	GET_SECTION_BOOL_HELPER(bSupportsGPUScene);
	GET_SECTION_BOOL_HELPER(bSupportsPrimitiveShaders);
	GET_SECTION_BOOL_HELPER(bSupportsUInt64ImageAtomics);
	GET_SECTION_BOOL_HELPER(bRequiresVendorExtensionsForAtomics);
	GET_SECTION_BOOL_HELPER(bSupportsNanite);
	GET_SECTION_BOOL_HELPER(bSupportsLumenGI);
	GET_SECTION_BOOL_HELPER(bSupportsSSDIndirect);
	GET_SECTION_BOOL_HELPER(bSupportsTemporalHistoryUpscale);
	GET_SECTION_BOOL_HELPER(bSupportsRTIndexFromVS);

#Loc: <Workspace>/Engine/Source/Runtime/RHI/Private/DataDrivenShaderPlatformInfo.cpp:460

Scope (from outer to inner):

file
function     void FGenericDataDrivenShaderPlatformInfo::UpdatePreviewPlatforms

Source code excerpt:

				PREVIEW_DISABLE_IF_RUNTIME_UNSUPPORTED(bSupportsLumenGI);
				PREVIEW_DISABLE_IF_RUNTIME_UNSUPPORTED(bSupportsPrimitiveShaders);
				PREVIEW_DISABLE_IF_RUNTIME_UNSUPPORTED(bSupportsUInt64ImageAtomics);
				PREVIEW_DISABLE_IF_RUNTIME_UNSUPPORTED(bSupportsGen5TemporalAA);
				PREVIEW_DISABLE_IF_RUNTIME_UNSUPPORTED(bSupportsInlineRayTracing);
				PREVIEW_DISABLE_IF_RUNTIME_UNSUPPORTED(bSupportsRayTracingShaders);
				PREVIEW_DISABLE_IF_RUNTIME_UNSUPPORTED(bSupportsMeshShadersTier0);
				PREVIEW_DISABLE_IF_RUNTIME_UNSUPPORTED(bSupportsMeshShadersTier1);
				PREVIEW_DISABLE_IF_RUNTIME_UNSUPPORTED(bSupportsMobileMultiView);

#Loc: <Workspace>/Engine/Source/Runtime/RHI/Public/DataDrivenShaderPlatformInfo.h:55

Scope (from outer to inner):

file
class        class FGenericDataDrivenShaderPlatformInfo

Source code excerpt:

	uint32 bSupportsByteBufferComputeShaders : 1;
	uint32 bSupportsPrimitiveShaders : 1;
	uint32 bSupportsUInt64ImageAtomics : 1;
	uint32 bRequiresVendorExtensionsForAtomics : 1;
	uint32 bSupportsNanite : 1;
	uint32 bSupportsLumenGI : 1;
	uint32 bSupportsSSDIndirect : 1;
	uint32 bSupportsTemporalHistoryUpscale : 1;
	uint32 bSupportsRTIndexFromVS : 1;

#Loc: <Workspace>/Engine/Source/Runtime/RHI/Public/DataDrivenShaderPlatformInfo.h:473

Scope (from outer to inner):

file
class        class FGenericDataDrivenShaderPlatformInfo
function     static const bool GetSupportsUInt64ImageAtomics

Source code excerpt:

	{
		check(IsValid(Platform));
		return Infos[Platform].bSupportsUInt64ImageAtomics;
	}

	static FORCEINLINE_DEBUGGABLE const bool GetRequiresVendorExtensionsForAtomics(const FStaticShaderPlatform Platform)
	{
		check(IsValid(Platform));
		return Infos[Platform].bRequiresVendorExtensionsForAtomics;