VK_NV_ray_tracing_linear_swept_spheres

Other Extension Metadata

Last Modified Date

2025-01-03

Interactions and External Dependencies

• This extension requires SPV_NV_linear_swept_spheres
• This extension provides API support for GL_NV_linear_swept_spheres

Contributors

• Vikram Kushwaha, NVIDIA
• Eric Werness, NVIDIA
• Daniel Koch, NVIDIA
• Ashwin Lele, NVIDIA
• Nathan Morrical, NVIDIA

Description

This extension adds two new primitives for ray tracing: a sphere primitive and a linear swept sphere (LSS) primitive. The purpose of the LSS primitive is to enable rendering of high quality hair and fur using a compact primitive representation encoded in the acceleration structure. Sphere primitives are defined by a position and a radius and are a subset of LSS, but are useful in their own right, for example for particle systems.

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

• SPV_NV_linear_swept_spheres

New Structures

• Extending VkAccelerationStructureGeometryKHR:
  • VkAccelerationStructureGeometryLinearSweptSpheresDataNV
  • VkAccelerationStructureGeometrySpheresDataNV
• Extending VkPhysicalDeviceFeatures2, VkDeviceCreateInfo:
  • VkPhysicalDeviceRayTracingLinearSweptSpheresFeaturesNV

New Enums

• VkRayTracingLssIndexingModeNV
• VkRayTracingLssPrimitiveEndCapsModeNV

New Enum Constants

• VK_NV_RAY_TRACING_LINEAR_SWEPT_SPHERES_EXTENSION_NAME
• VK_NV_RAY_TRACING_LINEAR_SWEPT_SPHERES_SPEC_VERSION
• Extending VkFormatFeatureFlagBits2:
  • VK_FORMAT_FEATURE_2_ACCELERATION_STRUCTURE_RADIUS_BUFFER_BIT_NV
• Extending VkGeometryTypeKHR:
  • VK_GEOMETRY_TYPE_LINEAR_SWEPT_SPHERES_NV
  • VK_GEOMETRY_TYPE_SPHERES_NV
• Extending VkPipelineCreateFlagBits2:
  • VK_PIPELINE_CREATE_2_RAY_TRACING_ALLOW_SPHERES_AND_LINEAR_SWEPT_SPHERES_BIT_NV
• Extending VkStructureType:
  • VK_STRUCTURE_TYPE_ACCELERATION_STRUCTURE_GEOMETRY_LINEAR_SWEPT_SPHERES_DATA_NV
  • VK_STRUCTURE_TYPE_ACCELERATION_STRUCTURE_GEOMETRY_SPHERES_DATA_NV
  • VK_STRUCTURE_TYPE_PHYSICAL_DEVICE_RAY_TRACING_LINEAR_SWEPT_SPHERES_FEATURES_NV

New or Modified Built-In Variables

• HitIsSphereNV
• HitIsLSSNV
• HitSpherePositionNV
• HitSphereRadiusNV
• HitLSSPositionsNV
• HitLSSRadiiNV

New SPIR-V Capabilities

• RayTracingSpheresGeometryNV
• RayTracingLinearSweptSpheresGeometryNV

Version History

• Revision 1, 2025-01-03 (Vikram Kushwaha)
  • Initial draft