VulkanHub

VK_KHR_ray_query

Other Extension Metadata

Last Modified Date

2020-11-12

Interactions and External Dependencies
Contributors
  • Matthäus Chajdas, AMD
  • Greg Grebe, AMD
  • Nicolai Hähnle, AMD
  • Tobias Hector, AMD
  • Dave Oldcorn, AMD
  • Skyler Saleh, AMD
  • Mathieu Robart, Arm
  • Marius Bjorge, Arm
  • Tom Olson, Arm
  • Sebastian Tafuri, EA
  • Henrik Rydgard, Embark
  • Juan Cañada, Epic Games
  • Patrick Kelly, Epic Games
  • Yuriy O’Donnell, Epic Games
  • Michael Doggett, Facebook/Oculus
  • Andrew Garrard, Imagination
  • Don Scorgie, Imagination
  • Dae Kim, Imagination
  • Joshua Barczak, Intel
  • Slawek Grajewski, Intel
  • Jeff Bolz, NVIDIA
  • Pascal Gautron, NVIDIA
  • Daniel Koch, NVIDIA
  • Christoph Kubisch, NVIDIA
  • Ashwin Lele, NVIDIA
  • Robert Stepinski, NVIDIA
  • Martin Stich, NVIDIA
  • Nuno Subtil, NVIDIA
  • Eric Werness, NVIDIA
  • Jon Leech, Khronos
  • Jeroen van Schijndel, OTOY
  • Juul Joosten, OTOY
  • Alex Bourd, Qualcomm
  • Roman Larionov, Qualcomm
  • David McAllister, Qualcomm
  • Spencer Fricke, Samsung
  • Lewis Gordon, Samsung
  • Ralph Potter, Samsung
  • Jasper Bekkers, Traverse Research
  • Jesse Barker, Unity
  • Baldur Karlsson, Valve

Description

Rasterization has been the dominant method to produce interactive graphics, but increasing performance of graphics hardware has made ray tracing a viable option for interactive rendering. Being able to integrate ray tracing with traditional rasterization makes it easier for applications to incrementally add ray traced effects to existing applications or to do hybrid approaches with rasterization for primary visibility and ray tracing for secondary queries.

Ray queries are available to all shader types, including graphics, compute and ray tracing pipelines. Ray queries are not able to launch additional shaders, instead returning traversal results to the calling shader.

This extension adds support for the following SPIR-V extension in Vulkan:

  • SPV_KHR_ray_query

New Structures

New Enum Constants

  • VK_KHR_RAY_QUERY_EXTENSION_NAME
  • VK_KHR_RAY_QUERY_SPEC_VERSION
  • Extending VkStructureType:
    • VK_STRUCTURE_TYPE_PHYSICAL_DEVICE_RAY_QUERY_FEATURES_KHR

New SPIR-V Capabilities

Sample Code

Example of ray query in a GLSL shader, illustrating how to use ray queries to determine whether a given position (at ray origin) is in shadow or not, by tracing a ray towards the light, and checking for any intersections with geometry occluding the light.

rayQueryEXT rq;

rayQueryInitializeEXT(rq, accStruct, gl_RayFlagsTerminateOnFirstHitEXT, cullMask, origin, tMin, direction, tMax);

// Traverse the acceleration structure and store information about the first intersection (if any)
rayQueryProceedEXT(rq);

if (rayQueryGetIntersectionTypeEXT(rq, true) == gl_RayQueryCommittedIntersectionNoneEXT) {
    // Not in shadow
}

Issues

(1) What are the changes between the public provisional (VK_KHR_ray_tracing v8) release and the final (VK_KHR_acceleration_structure v11 / VK_KHR_ray_query v1) release?

  • refactor VK_KHR_ray_tracing into 3 extensions, enabling implementation flexibility and decoupling ray query support from ray pipelines:
  • Update SPIRV capabilities to use RayQueryKHR
  • extension is no longer provisional

Version History

  • Revision 1, 2020-11-12 (Mathieu Robart, Daniel Koch, Andrew Garrard)
    • Decomposition of the specification, from VK_KHR_ray_tracing to VK_KHR_ray_query (#1918,!3912)
    • update to use RayQueryKHR SPIR-V capability
    • add numerical limits for ray parameters (#2235,!3960)
    • relax formula for ray intersection candidate determination (#2322,!4080)
    • restrict traces to TLAS (#2239,!4141)
    • require HitT to be in ray interval for OpRayQueryGenerateIntersectionKHR (#2359,!4146)
    • add ray query shader stages for AS read bit (#2407,!4203)