This structure is used by IDeviceContext::BuildTLAS(). More...

#include <DeviceContext.h>

Public Attributes
ITopLevelAS *	pTLAS = nullptr
	Target top-level AS.

RESOURCE_STATE_TRANSITION_MODE	TLASTransitionMode = RESOURCE_STATE_TRANSITION_MODE_NONE
	Top-level AS state transition mode (see Diligent::RESOURCE_STATE_TRANSITION_MODE).

RESOURCE_STATE_TRANSITION_MODE	BLASTransitionMode = RESOURCE_STATE_TRANSITION_MODE_NONE
	Bottom-level AS (in TLASBuildInstanceData::pBLAS) state transition mode (see Diligent::RESOURCE_STATE_TRANSITION_MODE).

TLASBuildInstanceData const *	pInstances = nullptr
	A pointer to an array of `InstanceCount` `TLASBuildInstanceData` structures that contain instance data.

Uint32	InstanceCount = 0
	The number of instances.

IBuffer *	pInstanceBuffer = nullptr
	The buffer that will be used to store instance data during AS building.

Uint64	InstanceBufferOffset = 0

RESOURCE_STATE_TRANSITION_MODE	InstanceBufferTransitionMode = RESOURCE_STATE_TRANSITION_MODE_NONE
	Instance buffer state transition mode (see Diligent::RESOURCE_STATE_TRANSITION_MODE).

Uint32	HitGroupStride = 1
	The number of hit shaders that can be bound for a single geometry or an instance (depends on BindingMode).

Uint32	BaseContributionToHitGroupIndex = 0
	Base offset for the hit group location.

HIT_GROUP_BINDING_MODE	BindingMode = HIT_GROUP_BINDING_MODE_PER_GEOMETRY
	Hit shader binding mode, see Diligent::SHADER_BINDING_MODE.

IBuffer *	pScratchBuffer = nullptr
	Buffer that is used for acceleration structure building.

Uint64	ScratchBufferOffset = 0
	Offset from the beginning of the buffer.

RESOURCE_STATE_TRANSITION_MODE	ScratchBufferTransitionMode = RESOURCE_STATE_TRANSITION_MODE_NONE
	Scratch buffer state transition mode (see Diligent::RESOURCE_STATE_TRANSITION_MODE).

Bool	Update = False
	Whether to build the acceleration structure from scratch or update it.

Detailed Description

This structure is used by IDeviceContext::BuildTLAS().

Member Data Documentation

◆ BaseContributionToHitGroupIndex

Uint32 Diligent::BuildTLASAttribs::BaseContributionToHitGroupIndex = 0

Base offset for the hit group location.

Can be used to bind hit shaders for multiple acceleration structures, see IShaderBindingTable::BindHitGroupForGeometry().

Used to calculate TLASBuildInstanceData::ContributionToHitGroupIndex.
Ignored if BindingMode is Diligent::SHADER_BINDING_USER_DEFINED.

◆ BindingMode

HIT_GROUP_BINDING_MODE Diligent::BuildTLASAttribs::BindingMode = HIT_GROUP_BINDING_MODE_PER_GEOMETRY

Hit shader binding mode, see Diligent::SHADER_BINDING_MODE.

Used to calculate TLASBuildInstanceData::ContributionToHitGroupIndex.

◆ HitGroupStride

Uint32 Diligent::BuildTLASAttribs::HitGroupStride = 1

The number of hit shaders that can be bound for a single geometry or an instance (depends on BindingMode).

Used to calculate TLASBuildInstanceData::ContributionToHitGroupIndex.
- Ignored if BindingMode is Diligent::SHADER_BINDING_USER_DEFINED.

You should use the same value in a shader:

MultiplierForGeometryContributionToHitGroupIndex argument in TraceRay() in HLSL
sbtRecordStride argument in traceRay() in GLSL.

◆ InstanceBufferOffset

Uint64 Diligent::BuildTLASAttribs::InstanceBufferOffset = 0

Offset from the beginning of the buffer to the location of instance data. Offset must be aligned by RayTracingProperties::InstanceBufferAlignment.

◆ InstanceCount

Uint32 Diligent::BuildTLASAttribs::InstanceCount = 0

The number of instances.

Must be less than or equal to TopLevelASDesc::MaxInstanceCount. If Update is true then count must be the same as used to build TLAS.

◆ pInstanceBuffer

IBuffer* Diligent::BuildTLASAttribs::pInstanceBuffer = nullptr

The buffer that will be used to store instance data during AS building.

The buffer size must be at least TLAS_INSTANCE_DATA_SIZE * InstanceCount. The buffer must be created with Diligent::BIND_RAY_TRACING flag.

◆ pInstances

TLASBuildInstanceData const* Diligent::BuildTLASAttribs::pInstances = nullptr

A pointer to an array of InstanceCount TLASBuildInstanceData structures that contain instance data.

If Update is true:

Any instance data can be changed.
To disable an instance set TLASBuildInstanceData::Mask to zero or set empty TLASBuildInstanceData::BLAS to pBLAS.

◆ pScratchBuffer

IBuffer* Diligent::BuildTLASAttribs::pScratchBuffer = nullptr

Buffer that is used for acceleration structure building.

Must be created with Diligent::BIND_RAY_TRACING.

Call ITopLevelAS::GetScratchBufferSizes().Build to get the minimal size for the scratch buffer.

Note: Access to the TLAS must be externally synchronized.

◆ pTLAS

ITopLevelAS* Diligent::BuildTLASAttribs::pTLAS = nullptr

Target top-level AS.

Access to the TLAS must be externally synchronized.

◆ ScratchBufferOffset

Uint64 Diligent::BuildTLASAttribs::ScratchBufferOffset = 0

Offset from the beginning of the buffer.

Offset must be aligned by RayTracingProperties::ScratchBufferAlignment.

◆ Update

Bool Diligent::BuildTLASAttribs::Update = False

Whether to build the acceleration structure from scratch or update it.

if false, then TLAS will be built from scratch.
If true, then previous content of TLAS will be updated.

pTLAS must be created with Diligent::RAYTRACING_BUILD_AS_ALLOW_UPDATE flag.

Note: An update will be faster than building an acceleration structure from scratch.

Public Attributes