## C Specification

The VkAccelerationStructureCreateInfoKHR structure is defined as:

// Provided by VK_KHR_acceleration_structure
typedef struct VkAccelerationStructureCreateInfoKHR {
VkStructureType                          sType;
const void*                              pNext;
VkAccelerationStructureCreateFlagsKHR    createFlags;
VkBuffer                                 buffer;
VkDeviceSize                             offset;
VkDeviceSize                             size;
VkAccelerationStructureTypeKHR           type;
} VkAccelerationStructureCreateInfoKHR;

## Members

• sType is the type of this structure.

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

• createFlags is a bitmask of VkAccelerationStructureCreateFlagBitsKHR specifying additional creation parameters of the acceleration structure.

• buffer is the buffer on which the acceleration structure will be stored.

• offset is an offset in bytes from the base address of the buffer at which the acceleration structure will be stored, and must be a multiple of 256.

• size is the size required for the acceleration structure.

• type is a VkAccelerationStructureTypeKHR value specifying the type of acceleration structure that will be created.

• deviceAddress is the device address requested for the acceleration structure if the accelerationStructureCaptureReplay feature is being used.

## Description

If deviceAddress is zero, no specific address is requested.

If deviceAddress is not zero, deviceAddress must be an address retrieved from an identically created acceleration structure on the same implementation. The acceleration structure must also be placed on an identically created buffer and at the same offset.

Applications should avoid creating acceleration structures with application-provided addresses and implementation-provided addresses in the same process, to reduce the likelihood of VK_ERROR_INVALID_OPAQUE_CAPTURE_ADDRESS_KHR errors.

 Note The expected usage for this is that a trace capture/replay tool will add the VK_BUFFER_CREATE_DEVICE_ADDRESS_CAPTURE_REPLAY_BIT flag to all buffers that use VK_BUFFER_USAGE_SHADER_DEVICE_ADDRESS_BIT, and will add VK_BUFFER_USAGE_SHADER_DEVICE_ADDRESS_BIT to all buffers used as storage for an acceleration structure where deviceAddress is not zero. This also means that the tool will need to add VK_MEMORY_ALLOCATE_DEVICE_ADDRESS_BIT to memory allocations to allow the flag to be set where the application may not have otherwise required it. During capture the tool will save the queried opaque device addresses in the trace. During replay, the buffers will be created specifying the original address so any address values stored in the trace data will remain valid. Implementations are expected to separate such buffers in the GPU address space so normal allocations will avoid using these addresses. Apps/tools should avoid mixing app-provided and implementation-provided addresses for buffers created with VK_BUFFER_CREATE_DEVICE_ADDRESS_CAPTURE_REPLAY_BIT, to avoid address space allocation conflicts.

Applications should create an acceleration structure with a specific VkAccelerationStructureTypeKHR other than VK_ACCELERATION_STRUCTURE_TYPE_GENERIC_KHR.

If the acceleration structure will be the target of a build operation, the required size for an acceleration structure can be queried with vkGetAccelerationStructureBuildSizesKHR. If the acceleration structure is going to be the target of a compacting copy, vkCmdWriteAccelerationStructuresPropertiesKHR or vkWriteAccelerationStructuresPropertiesKHR can be used to obtain the compacted size required.

If the acceleration structure will be the target of a build operation with VK_BUILD_ACCELERATION_STRUCTURE_MOTION_BIT_NV it must include VK_ACCELERATION_STRUCTURE_CREATE_MOTION_BIT_NV in flags and include VkAccelerationStructureMotionInfoNV as an extension structure in pNext with the number of instances as metadata for the object.

Valid Usage
If deviceAddress is not zero, createFlags must include VK_ACCELERATION_STRUCTURE_CREATE_DEVICE_ADDRESS_CAPTURE_REPLAY_BIT_KHR

• VUID-VkAccelerationStructureCreateInfoKHR-createFlags-03613
If createFlags includes VK_ACCELERATION_STRUCTURE_CREATE_DEVICE_ADDRESS_CAPTURE_REPLAY_BIT_KHR, VkPhysicalDeviceAccelerationStructureFeaturesKHR::accelerationStructureCaptureReplay must be VK_TRUE

• VUID-VkAccelerationStructureCreateInfoKHR-buffer-03614
buffer must have been created with a usage value containing VK_BUFFER_USAGE_ACCELERATION_STRUCTURE_STORAGE_BIT_KHR

• VUID-VkAccelerationStructureCreateInfoKHR-buffer-03615
buffer must not have been created with VK_BUFFER_CREATE_SPARSE_RESIDENCY_BIT

• VUID-VkAccelerationStructureCreateInfoKHR-offset-03616
The sum of offset and size must be less than the size of buffer

• VUID-VkAccelerationStructureCreateInfoKHR-offset-03734
offset must be a multiple of 256 bytes

• VUID-VkAccelerationStructureCreateInfoKHR-flags-04954
If VK_ACCELERATION_STRUCTURE_CREATE_MOTION_BIT_NV is set in flags and type is VK_ACCELERATION_STRUCTURE_TYPE_TOP_LEVEL_KHR, one member of the pNext chain must be a pointer to a valid instance of VkAccelerationStructureMotionInfoNV

• VUID-VkAccelerationStructureCreateInfoKHR-flags-04955
If any geometry includes VkAccelerationStructureGeometryMotionTrianglesDataNV then flags must contain VK_ACCELERATION_STRUCTURE_CREATE_MOTION_BIT_NV

Valid Usage (Implicit)
• VUID-VkAccelerationStructureCreateInfoKHR-sType-sType
sType must be VK_STRUCTURE_TYPE_ACCELERATION_STRUCTURE_CREATE_INFO_KHR

• VUID-VkAccelerationStructureCreateInfoKHR-pNext-pNext
pNext must be NULL or a pointer to a valid instance of VkAccelerationStructureMotionInfoNV

• VUID-VkAccelerationStructureCreateInfoKHR-sType-unique
The sType value of each struct in the pNext chain must be unique

• VUID-VkAccelerationStructureCreateInfoKHR-createFlags-parameter
createFlags must be a valid combination of VkAccelerationStructureCreateFlagBitsKHR values

• VUID-VkAccelerationStructureCreateInfoKHR-buffer-parameter
buffer must be a valid VkBuffer handle

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