VK_NV_displacement_micromap

Other Extension Metadata

Last Modified Date

2023-03-17

Interactions and External Dependencies

TBD

Contributors

• Christoph Kubisch, NVIDIA
• Eric Werness, NVIDIA

Description

Ray tracing can very efficiently render from geometry which has very fine detail, but when using only a basic triangle representation, memory consumption can be an issue. This extension adds the ability to add a displacement map to add more detail to triangles in an acceleration structure with an efficient in-memory format. The format is externally visible to allow the application to compress its internal geometry representations into the compressed format ahead of time. This format adds displacements along a defined vector to subtriangle vertices which are subdivided from the main triangles.

This extension provides:

• a new VkMicromapTypeEXT format for the displacement micromap,
• a structure to extend VkAccelerationStructureGeometryTrianglesDataKHR to attach a displacement micromap to the geometry of the acceleration structure,
• enums extending VkBuildAccelerationStructureFlagBitsKHR to allow for updates.

New Structures

• Extending VkAccelerationStructureGeometryTrianglesDataKHR:
  • VkAccelerationStructureTrianglesDisplacementMicromapNV
• Extending VkPhysicalDeviceFeatures2, VkDeviceCreateInfo:
  • VkPhysicalDeviceDisplacementMicromapFeaturesNV
• Extending VkPhysicalDeviceProperties2:
  • VkPhysicalDeviceDisplacementMicromapPropertiesNV

New Enums

• VkDisplacementMicromapFormatNV

New Enum Constants

• VK_NV_DISPLACEMENT_MICROMAP_EXTENSION_NAME
• VK_NV_DISPLACEMENT_MICROMAP_SPEC_VERSION
• Extending VkBuildAccelerationStructureFlagBitsKHR:
  • VK_BUILD_ACCELERATION_STRUCTURE_ALLOW_DISPLACEMENT_MICROMAP_UPDATE_NV
• Extending VkMicromapTypeEXT:
  • VK_MICROMAP_TYPE_DISPLACEMENT_MICROMAP_NV
• Extending VkPipelineCreateFlagBits:
  • VK_PIPELINE_CREATE_RAY_TRACING_DISPLACEMENT_MICROMAP_BIT_NV
• Extending VkStructureType:
  • VK_STRUCTURE_TYPE_ACCELERATION_STRUCTURE_TRIANGLES_DISPLACEMENT_MICROMAP_NV
  • VK_STRUCTURE_TYPE_PHYSICAL_DEVICE_DISPLACEMENT_MICROMAP_FEATURES_NV
  • VK_STRUCTURE_TYPE_PHYSICAL_DEVICE_DISPLACEMENT_MICROMAP_PROPERTIES_NV

Issues

(1) What is the status of this extension?

• Provisional and expected to change. The broad structure and encoding format are stable, but there will likely be changes to the structures, enumerant values, and shader interface.

Version History

• Revision 1, 2023-03-17 (Eric Werness)
  • Initial public revision
• Revision 2, 2023-07-07 (Eric Werness)
  • Add shader support for decode intrinsics