bSupportsRayTracingIndirectInstanceData

bSupportsRayTracingIndirectInstanceData

#Overview

name: bSupportsRayTracingIndirectInstanceData

The value of this variable can be defined or overridden in .ini config files. 7 .ini config files referencing this setting variable.

It is referenced in 3 C++ source files.

#Summary

#Usage in the C++ source code

The purpose of bSupportsRayTracingIndirectInstanceData is to indicate whether the GPU platform supports copying instance transforms from the GPU to the Traversal Acceleration Structure (TLAS) instances buffer in ray tracing operations.

This setting variable is primarily used by the Unreal Engine’s rendering system, specifically in the Ray Tracing subsystem. It’s part of the RHI (Rendering Hardware Interface) module, which provides an abstraction layer for different graphics APIs.

The value of this variable is set in the FGenericDataDrivenShaderPlatformInfo class, which is responsible for parsing and storing shader platform information. It’s likely initialized from a configuration file or determined based on the capabilities of the current graphics hardware.

This variable interacts closely with other ray tracing related variables, such as bSupportsRayTracing and bSupportsRayTracingProceduralPrimitive. It’s part of a larger set of flags that define the ray tracing capabilities of the current platform.

Developers must be aware that this variable is platform-specific. Its value may differ depending on the target hardware and graphics API. It’s crucial to check this flag before attempting to use indirect instance data in ray tracing operations to ensure compatibility across different platforms.

Best practices when using this variable include:

1. Always check its value using the GetSupportsRayTracingIndirectInstanceData() function before implementing related functionality.
2. Consider providing fallback methods for platforms that don’t support this feature.
3. Use it in conjunction with other ray tracing capability flags to ensure full compatibility.
4. Be aware of potential performance implications when this feature is supported and used, as it involves GPU-to-GPU memory transfers.

#Setting Variables

#References In INI files

Location: <Workspace>/Engine/Config/Android/DataDrivenPlatformInfo.ini:113, section: [ShaderPlatform VULKAN_SM5_ANDROID]

• INI Section: ShaderPlatform VULKAN_SM5_ANDROID
• Raw value: true
• Is Array: False

Location: <Workspace>/Engine/Config/Mac/DataDrivenPlatformInfo.ini:58, section: [ShaderPlatform METAL_SM5]

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

Location: <Workspace>/Engine/Config/Mac/DataDrivenPlatformInfo.ini:98, section: [ShaderPlatform METAL_SM6]

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

Location: <Workspace>/Engine/Config/VulkanPC/DataDrivenPlatformInfo.ini:53, section: [ShaderPlatform VULKAN_SM5]

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

Location: <Workspace>/Engine/Config/VulkanPC/DataDrivenPlatformInfo.ini:177, section: [ShaderPlatform VULKAN_SM6]

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

Location: <Workspace>/Engine/Config/Windows/DataDrivenPlatformInfo.ini:46, section: [ShaderPlatform PCD3D_SM5]

• INI Section: ShaderPlatform PCD3D_SM5
• Raw value: true
• Is Array: False

Location: <Workspace>/Engine/Config/Windows/DataDrivenPlatformInfo.ini:97, 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:225

Scope (from outer to inner):

file
function     void FGenericDataDrivenShaderPlatformInfo::ParseDataDrivenShaderInfo

Source code excerpt:

	GET_SECTION_BOOL_HELPER(bSupportsRayTracingProceduralPrimitive);
	GET_SECTION_BOOL_HELPER(bSupportsRayTracingTraversalStatistics);
	GET_SECTION_BOOL_HELPER(bSupportsRayTracingIndirectInstanceData);
	GET_SECTION_BOOL_HELPER(bSupportsPathTracing);
	GET_SECTION_BOOL_HELPER(bSupportsHighEndRayTracingEffects);
	GET_SECTION_BOOL_HELPER(bSupportsByteBufferComputeShaders);
	GET_SECTION_BOOL_HELPER(bSupportsGPUScene);
	GET_SECTION_BOOL_HELPER(bSupportsPrimitiveShaders);
	GET_SECTION_BOOL_HELPER(bSupportsUInt64ImageAtomics);

#Loc: <Workspace>/Engine/Source/Runtime/RHI/Public/DataDrivenShaderPlatformInfo.h:49

Scope (from outer to inner):

file
class        class FGenericDataDrivenShaderPlatformInfo

Source code excerpt:

	uint32 bSupportsRayTracingProceduralPrimitive : 1;
	uint32 bSupportsRayTracingTraversalStatistics : 1;
	uint32 bSupportsRayTracingIndirectInstanceData : 1; // Whether instance transforms can be copied from the GPU to the TLAS instances buffer
	uint32 bSupportsHighEndRayTracingEffects : 1; // Whether fully-featured RT effects can be used on the platform (with translucent shadow, etc.)
	uint32 bSupportsPathTracing : 1; // Whether real-time path tracer is supported on this platform (avoids compiling unnecessary shaders)
	uint32 bSupportsGPUScene : 1;
	uint32 bSupportsByteBufferComputeShaders : 1;
	uint32 bSupportsPrimitiveShaders : 1;
	uint32 bSupportsUInt64ImageAtomics : 1;

#Loc: <Workspace>/Engine/Source/Runtime/RHI/Public/DataDrivenShaderPlatformInfo.h:377

Scope (from outer to inner):

file
class        class FGenericDataDrivenShaderPlatformInfo
function     static const bool GetSupportsRayTracingIndirectInstanceData

Source code excerpt:

	{
		check(IsValid(Platform));
		return Infos[Platform].bSupportsRayTracing && Infos[Platform].bSupportsRayTracingIndirectInstanceData;
	}

	static FORCEINLINE_DEBUGGABLE const bool GetSupportsPathTracing(const FStaticShaderPlatform Platform)
	{
		check(IsValid(Platform));
		return Infos[Platform].bSupportsRayTracing && Infos[Platform].bSupportsPathTracing;