C Specification

The VkAccelerationStructureBuildGeometryInfoKHR structure is defined as:

// Provided by VK_KHR_acceleration_structure
typedef struct VkAccelerationStructureBuildGeometryInfoKHR {
    VkStructureType                                     sType;
    const void*                                         pNext;
    VkAccelerationStructureTypeKHR                      type;
    VkBuildAccelerationStructureFlagsKHR                flags;
    VkBuildAccelerationStructureModeKHR                 mode;
    VkAccelerationStructureKHR                          srcAccelerationStructure;
    VkAccelerationStructureKHR                          dstAccelerationStructure;
    uint32_t                                            geometryCount;
    const VkAccelerationStructureGeometryKHR*           pGeometries;
    const VkAccelerationStructureGeometryKHR* const*    ppGeometries;
    VkDeviceOrHostAddressKHR                            scratchData;
} VkAccelerationStructureBuildGeometryInfoKHR;

Members

  • sType is the type of this structure.

  • pNext is NULL or a pointer to a structure extending this structure.

  • type is a VkAccelerationStructureTypeKHR value specifying the type of acceleration structure being built.

  • flags is a bitmask of VkBuildAccelerationStructureFlagBitsKHR specifying additional parameters of the acceleration structure.

  • mode is a VkBuildAccelerationStructureModeKHR value specifying the type of operation to perform.

  • srcAccelerationStructure is a pointer to an existing acceleration structure that is to be used to update the dst acceleration structure when mode is VK_BUILD_ACCELERATION_STRUCTURE_MODE_UPDATE_KHR.

  • dstAccelerationStructure is a pointer to the target acceleration structure for the build.

  • geometryCount specifies the number of geometries that will be built into dstAccelerationStructure.

  • pGeometries is a pointer to an array of VkAccelerationStructureGeometryKHR structures.

  • ppGeometries is a pointer to an array of pointers to VkAccelerationStructureGeometryKHR structures.

  • scratchData is the device or host address to memory that will be used as scratch memory for the build.

Description

Only one of pGeometries or ppGeometries can be a valid pointer, the other must be NULL. Each element of the non-NULL array describes the data used to build each acceleration structure geometry.

The index of each element of the pGeometries or ppGeometries members of VkAccelerationStructureBuildGeometryInfoKHR is used as the geometry index during ray traversal. The geometry index is available in ray shaders via the RayGeometryIndexKHR built-in, and is used to determine hit and intersection shaders executed during traversal. The geometry index is available to ray queries via the OpRayQueryGetIntersectionGeometryIndexKHR instruction.

Setting VK_BUILD_ACCELERATION_STRUCTURE_MOTION_BIT_NV in flags indicates that this build is a motion top level acceleration structure. A motion top level uses instances of format VkAccelerationStructureMotionInstanceNV if VkAccelerationStructureGeometryInstancesDataKHR::arrayOfPointers is VK_FALSE.

If VkAccelerationStructureGeometryInstancesDataKHR::arrayOfPointers is VK_TRUE, the pointer for any given element of the array of instance pointers consists of 4 bits of VkAccelerationStructureMotionInstanceTypeNV in the low 4 bits of the pointer identifying the type of structure at the pointer. The device address accessed is the value in the array with the low 4 bits set to zero. The structure at the pointer is one of VkAccelerationStructureInstanceKHR, VkAccelerationStructureMatrixMotionInstanceNV or VkAccelerationStructureSRTMotionInstanceNV, depending on the type value encoded in the low 4 bits.

A top level acceleration structure with either motion instances or vertex motion in its instances must set VK_BUILD_ACCELERATION_STRUCTURE_MOTION_BIT_NV in flags.

Valid Usage

  • VUID-VkAccelerationStructureBuildGeometryInfoKHR-type-03654
    type must not be VK_ACCELERATION_STRUCTURE_TYPE_GENERIC_KHR

  • VUID-VkAccelerationStructureBuildGeometryInfoKHR-pGeometries-03788
    Only one of pGeometries or ppGeometries can be a valid pointer, the other must be NULL

  • VUID-VkAccelerationStructureBuildGeometryInfoKHR-type-03789
    If type is VK_ACCELERATION_STRUCTURE_TYPE_TOP_LEVEL_KHR, the geometryType member of elements of either pGeometries or ppGeometries must be VK_GEOMETRY_TYPE_INSTANCES_KHR

  • VUID-VkAccelerationStructureBuildGeometryInfoKHR-type-03790
    If type is VK_ACCELERATION_STRUCTURE_TYPE_TOP_LEVEL_KHR, geometryCount must be 1

  • VUID-VkAccelerationStructureBuildGeometryInfoKHR-type-03791
    If type is VK_ACCELERATION_STRUCTURE_TYPE_BOTTOM_LEVEL_KHR the geometryType member of elements of either pGeometries or ppGeometries must not be VK_GEOMETRY_TYPE_INSTANCES_KHR

  • VUID-VkAccelerationStructureBuildGeometryInfoKHR-type-03792
    If type is VK_ACCELERATION_STRUCTURE_TYPE_BOTTOM_LEVEL_KHR then the geometryType member of each geometry in either pGeometries or ppGeometries must be the same

  • VUID-VkAccelerationStructureBuildGeometryInfoKHR-type-03793
    If type is VK_ACCELERATION_STRUCTURE_TYPE_BOTTOM_LEVEL_KHR then geometryCount must be less than or equal to VkPhysicalDeviceAccelerationStructurePropertiesKHR::maxGeometryCount

  • VUID-VkAccelerationStructureBuildGeometryInfoKHR-type-03794
    If type is VK_ACCELERATION_STRUCTURE_TYPE_BOTTOM_LEVEL_KHR and the geometryType member of either pGeometries or ppGeometries is VK_GEOMETRY_TYPE_AABBS_KHR, the total number of AABBs in all geometries must be less than or equal to VkPhysicalDeviceAccelerationStructurePropertiesKHR::maxPrimitiveCount

  • VUID-VkAccelerationStructureBuildGeometryInfoKHR-type-03795
    If type is VK_ACCELERATION_STRUCTURE_TYPE_BOTTOM_LEVEL_KHR and the geometryType member of either pGeometries or ppGeometries is VK_GEOMETRY_TYPE_TRIANGLES_KHR, the total number of triangles in all geometries must be less than or equal to VkPhysicalDeviceAccelerationStructurePropertiesKHR::maxPrimitiveCount

  • VUID-VkAccelerationStructureBuildGeometryInfoKHR-flags-03796
    If flags has the VK_BUILD_ACCELERATION_STRUCTURE_PREFER_FAST_TRACE_BIT_KHR bit set, then it must not have the VK_BUILD_ACCELERATION_STRUCTURE_PREFER_FAST_BUILD_BIT_KHR bit set

  • VUID-VkAccelerationStructureBuildGeometryInfoKHR-dstAccelerationStructure-04927
    If dstAccelerationStructure was created with VK_ACCELERATION_STRUCTURE_CREATE_MOTION_BIT_NV set in VkAccelerationStructureCreateInfoKHR::flags, VK_BUILD_ACCELERATION_STRUCTURE_MOTION_BIT_NV must be set in flags

  • VUID-VkAccelerationStructureBuildGeometryInfoKHR-flags-04928
    If VK_BUILD_ACCELERATION_STRUCTURE_MOTION_BIT_NV is set in flags, dstAccelerationStructure must have been created with VK_ACCELERATION_STRUCTURE_CREATE_MOTION_BIT_NV set in VkAccelerationStructureCreateInfoKHR::flags

  • VUID-VkAccelerationStructureBuildGeometryInfoKHR-flags-04929
    If VK_BUILD_ACCELERATION_STRUCTURE_MOTION_BIT_NV is set in flags, type must not be VK_ACCELERATION_STRUCTURE_TYPE_GENERIC_KHR

Valid Usage (Implicit)

  • VUID-VkAccelerationStructureBuildGeometryInfoKHR-sType-sType
    sType must be VK_STRUCTURE_TYPE_ACCELERATION_STRUCTURE_BUILD_GEOMETRY_INFO_KHR

  • VUID-VkAccelerationStructureBuildGeometryInfoKHR-pNext-pNext
    pNext must be NULL

  • VUID-VkAccelerationStructureBuildGeometryInfoKHR-type-parameter
    type must be a valid VkAccelerationStructureTypeKHR value

  • VUID-VkAccelerationStructureBuildGeometryInfoKHR-flags-parameter
    flags must be a valid combination of VkBuildAccelerationStructureFlagBitsKHR values

  • VUID-VkAccelerationStructureBuildGeometryInfoKHR-pGeometries-parameter
    If geometryCount is not 0, and pGeometries is not NULL, pGeometries must be a valid pointer to an array of geometryCount valid VkAccelerationStructureGeometryKHR structures

  • VUID-VkAccelerationStructureBuildGeometryInfoKHR-ppGeometries-parameter
    If geometryCount is not 0, and ppGeometries is not NULL, ppGeometries must be a valid pointer to an array of geometryCount valid pointers to valid VkAccelerationStructureGeometryKHR structures

  • VUID-VkAccelerationStructureBuildGeometryInfoKHR-commonparent
    Both of dstAccelerationStructure, and srcAccelerationStructure that are valid handles of non-ignored parameters must have been created, allocated, or retrieved from the same VkDevice

See Also

VkAccelerationStructureGeometryKHR, VkAccelerationStructureKHR, VkAccelerationStructureTypeKHR, VkBuildAccelerationStructureFlagsKHR, VkBuildAccelerationStructureModeKHR, VkDeviceOrHostAddressKHR, VkStructureType, vkBuildAccelerationStructuresKHR, vkCmdBuildAccelerationStructuresIndirectKHR, vkCmdBuildAccelerationStructuresKHR, vkGetAccelerationStructureBuildSizesKHR

Document Notes

For more information, see the Vulkan Specification

This page is extracted from the Vulkan Specification. Fixes and changes should be made to the Specification, not directly.

Copyright

Copyright 2014-2021 The Khronos Group Inc.

SPDX-License-Identifier: CC-BY-4.0