vkCmdCopyAccelerationStructureToMemoryKHR(3)

C Specification

To copy an acceleration structure to device memory call:

// Provided by VK_KHR_acceleration_structure
void vkCmdCopyAccelerationStructureToMemoryKHR(
    VkCommandBuffer                             commandBuffer,
    const VkCopyAccelerationStructureToMemoryInfoKHR* pInfo);

Parameters

commandBuffer is the command buffer into which the command will be recorded.
pInfo is a pointer to a VkCopyAccelerationStructureToMemoryInfoKHR structure defining the copy operation.

Description

Accesses to pInfo->src must be synchronized with the VK_PIPELINE_STAGE_2_ACCELERATION_STRUCTURE_COPY_BIT_KHR pipeline stage or the VK_PIPELINE_STAGE_ACCELERATION_STRUCTURE_BUILD_BIT_KHR pipeline stage, and an access type of VK_ACCESS_ACCELERATION_STRUCTURE_READ_BIT_KHR. Accesses to the buffer indicated by pInfo->dst.deviceAddress must be synchronized with the VK_PIPELINE_STAGE_2_ACCELERATION_STRUCTURE_COPY_BIT_KHR pipeline stage or the VK_PIPELINE_STAGE_ACCELERATION_STRUCTURE_BUILD_BIT_KHR pipeline stage, and an access type of VK_ACCESS_TRANSFER_WRITE_BIT.

This command produces the same results as vkCopyAccelerationStructureToMemoryKHR, but writes its result to a device address, and is executed on the device rather than the host. The output may not necessarily be bit-for-bit identical, but it can be equally used by either vkCmdCopyMemoryToAccelerationStructureKHR or vkCopyMemoryToAccelerationStructureKHR.

The defined header structure for the serialized data consists of:

VK_UUID_SIZE bytes of data matching VkPhysicalDeviceIDProperties::driverUUID
VK_UUID_SIZE bytes of data identifying the compatibility for comparison using vkGetDeviceAccelerationStructureCompatibilityKHR
A 64-bit integer of the total size matching the value queried using VK_QUERY_TYPE_ACCELERATION_STRUCTURE_SERIALIZATION_SIZE_KHR
A 64-bit integer of the deserialized size to be passed in to VkAccelerationStructureCreateInfoKHR::size
A 64-bit integer of the count of the number of acceleration structure handles following. This value matches the value queried using VK_QUERY_TYPE_ACCELERATION_STRUCTURE_SERIALIZATION_BOTTOM_LEVEL_POINTERS_KHR. This will be zero for a bottom-level acceleration structure. For top-level acceleration structures this number is implementation-dependent; the number of and ordering of the handles may not match the instance descriptions which were used to build the acceleration structure.

The corresponding handles matching the values returned by vkGetAccelerationStructureDeviceAddressKHR or vkGetAccelerationStructureHandleNV are tightly packed in the buffer following the count. The application is expected to store a mapping between those handles and the original application-generated bottom-level acceleration structures to provide when deserializing. The serialized data is written to the buffer (or read from the buffer) according to the host endianness.

Valid Usage

VUID-vkCmdCopyAccelerationStructureToMemoryKHR-accelerationStructure-08926
The VkPhysicalDeviceAccelerationStructureFeaturesKHR::accelerationStructure feature must be enabled
VUID-vkCmdCopyAccelerationStructureToMemoryKHR-pInfo-03739
pInfo->dst.deviceAddress must be a valid VkDeviceAddress
VUID-vkCmdCopyAccelerationStructureToMemoryKHR-pInfo-03740
pInfo->dst.deviceAddress must be aligned to 256 bytes
VUID-vkCmdCopyAccelerationStructureToMemoryKHR-None-03559
The buffer used to create pInfo->src must be bound to device memory

Valid Usage (Implicit)

VUID-vkCmdCopyAccelerationStructureToMemoryKHR-commandBuffer-parameter
commandBuffer must be a valid VkCommandBuffer handle
VUID-vkCmdCopyAccelerationStructureToMemoryKHR-pInfo-parameter
pInfo must be a valid pointer to a valid VkCopyAccelerationStructureToMemoryInfoKHR structure
VUID-vkCmdCopyAccelerationStructureToMemoryKHR-commandBuffer-recording
commandBuffer must be in the recording state
VUID-vkCmdCopyAccelerationStructureToMemoryKHR-commandBuffer-cmdpool
The VkCommandPool that commandBuffer was allocated from must support VK_QUEUE_COMPUTE_BIT operations
VUID-vkCmdCopyAccelerationStructureToMemoryKHR-renderpass
This command must only be called outside of a render pass instance
VUID-vkCmdCopyAccelerationStructureToMemoryKHR-suspended
This command must not be called between suspended render pass instances
VUID-vkCmdCopyAccelerationStructureToMemoryKHR-videocoding
This command must only be called outside of a video coding scope

Host Synchronization

Host access to commandBuffer must be externally synchronized
Host access to the VkCommandPool that commandBuffer was allocated from must be externally synchronized