VK_KHR_ray_tracing_position_fetch(3)

# VK_KHR_ray_tracing_position_fetch(3) Manual Page

## Name

VK_KHR_ray_tracing_position_fetch - device extension

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## Registered Extension Number

482

## Revision

1

## Ratification Status

Ratified

## Extension and Version Dependencies

VK_KHR_acceleration_structure

## Contact

- Eric Werness

## Extension Proposal

VK_KHR_ray_tracing_position_fetch

## Other Extension Metadata

Last Modified Date

  2023-02-17

Interactions and External Dependencies

  - This extension requires `SPV_KHR_ray_tracing_position_fetch`

  - This extension provides API support for `GLSL_EXT_ray_tracing_position_fetch`

  - Interacts with `VK_KHR_ray_tracing_pipeline`

  - Interacts with `VK_KHR_ray_query`

Contributors

  - Eric Werness, NVIDIA

  - Stu Smith, AMD

  - Yuriy O’Donnell, Epic Games

  - Ralph Potter, Samsung

  - Joshua Barczak, Intel

  - Lionel Landwerlin, Intel

  - Andrew Garrard, Imagination Technologies

  - Alex Bourd, Qualcomm

  - Yunpeng Zhu, Huawei Technologies

  - Marius Bjorge, Arm

  - Daniel Koch, NVIDIA

## Description

`VK_KHR_ray_tracing_position_fetch` adds the ability to fetch the vertex positions in the shader from a hit triangle as stored in the acceleration structure.

An application adds `VK_BUILD_ACCELERATION_STRUCTURE_ALLOW_DATA_ACCESS_KHR` to the acceleration structure at build time. Then, if the hit is a triangle geometry, the shader (any-hit or closest hit for ray pipelines or using ray query) can fetch the three, three-component vertex positions in object space, of the triangle which was hit.

## New Structures

- Extending VkPhysicalDeviceFeatures2, VkDeviceCreateInfo:

  - VkPhysicalDeviceRayTracingPositionFetchFeaturesKHR

## New Enum Constants

- `VK_KHR_RAY_TRACING_POSITION_FETCH_EXTENSION_NAME`

- `VK_KHR_RAY_TRACING_POSITION_FETCH_SPEC_VERSION`

- Extending VkBuildAccelerationStructureFlagBitsKHR:

  - `VK_BUILD_ACCELERATION_STRUCTURE_ALLOW_DATA_ACCESS_KHR`

- Extending VkStructureType:

  - `VK_STRUCTURE_TYPE_PHYSICAL_DEVICE_RAY_TRACING_POSITION_FETCH_FEATURES_KHR`

## New Built-In Variables

- `HitTriangleVertexPositionsKHR`

## New SPIR-V Capabilities

- RayTracingPositionFetchKHR

## Issues

None Yet!

## Version History

- Revision 1, 2023-02-17 (Eric Werness)

  - internal revisions

## See Also

VkPhysicalDeviceRayTracingPositionFetchFeaturesKHR

## Document Notes

For more information, see the Vulkan Specification

This page is a generated document. Fixes and changes should be made to the generator scripts, not directly.

## Copyright

Copyright 2014-2023 The Khronos Group Inc.

SPDX-License-Identifier: CC-BY-4.0