foray::as::GeometryMetaBuffer Class Reference

Device local buffer maintaining GeometryMeta structs for all primitives/geometries for multiple BLAS. More...

#include <foray_geometrymetabuffer.hpp>

Public Member Functions
const std::unordered_map< const Blas *, uint32_t > &	CreateOrUpdate (core::Context *context, const std::unordered_set< const Blas * > &entries)
	(re)creates the meta buffer
VkDescriptorBufferInfo	GetVkDescriptorInfo () const

Protected Attributes
core::Context *	mContext = nullptr
std::unordered_map< const Blas *, uint32_t >	mBufferOffsets
	Maps BLAS to their offsets into the BlasMetaBuffers GeometryMeta array.
core::ManagedBuffer	mBuffer
	The device local buffer holding the array.

Detailed Description

Device local buffer maintaining GeometryMeta structs for all primitives/geometries for multiple BLAS.

DATA LAYOUT / USAGE

initialize with a set of BLAS. BLAS are assigned sections in the buffer consecutively:

| BLAS #0           | BLAS #1      | BLAS #2                     | // Unique BLAS

The amount of space assigned per BLAS is GeometryCount * sizeof(GeometryMeta)

| BLAS #0           | BLAS #1      | BLAS #2                     | // Unique BLAS
| G0 | G1 | G2 | G3 | G0 | G1 | G2 | G0 | G1 | G2 | G3 | G4 | G5 | // Geometry Meta structs (1x per Geometry per BLAS)

The buffer maintains the offsets into this buffer for each BLAS

| BLAS #0           | BLAS #1      | BLAS #2                     | // Unique BLAS
| G0 | G1 | G2 | G3 | G0 | G1 | G2 | G0 | G1 | G2 | G3 | G4 | G5 | // Geometry Meta structs (1x per Geometry per BLAS)
  ^                   ^              ^
  |                   |              |
  0                   4              7                             // Offset per BLAS into the Geometry Meta Array

These offsets are the return value of GeometryMetaBuffer::CreateOrUpdate and can be later retrieved via GeometryMetaBuffer::GetBufferOffsets()

Intended use for these offsets is to set them as VkAccelerationStructureInstanceKHR::instanceCustomIndex in BLAS instances installed into a TLAS. In rt shaders the correct meta struct can be accessed by geoMetaindex = gl_InstanceCustomIndexEXT + gl_GeometryIndexEXT;

gl_InstanceCustomIndexEXT: The custom index returned by the GeometryMetaBuffer and set as part of the BLAS instance struct in the TLAS gl_GeometryIndexEXT: The index of the geometry within the current BLAS

Member Function Documentation

CreateOrUpdate()

const std::unordered_map< const Blas *, uint32_t > & foray::as::GeometryMetaBuffer::CreateOrUpdate	(	core::Context *	context,
		const std::unordered_set< const Blas * > &	entries
	)

(re)creates the meta buffer

GetVkDescriptorInfo()

VkDescriptorBufferInfo foray::as::GeometryMetaBuffer::GetVkDescriptorInfo ( ) const

inline

Member Data Documentation

mBuffer

core::ManagedBuffer foray::as::GeometryMetaBuffer::mBuffer

protected

The device local buffer holding the array.

mBufferOffsets

std::unordered_map<const Blas*, uint32_t> foray::as::GeometryMetaBuffer::mBufferOffsets

protected

Maps BLAS to their offsets into the BlasMetaBuffers GeometryMeta array.

mContext

core::Context* foray::as::GeometryMetaBuffer::mContext = nullptr

protected

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The documentation for this class was generated from the following file:

• src/as/foray_geometrymetabuffer.hpp