C Specification

To copy an acceleration structure to device memory call:

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



Accesses to pInfo->src must be synchronized with 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_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 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-pInfo-03739
    pInfo->dst.deviceAddress must be a valid device address for a buffer bound to device memory.

  • VUID-vkCmdCopyAccelerationStructureToMemoryKHR-pInfo-03740
    pInfo->dst.deviceAddress must be aligned to 256 bytes

  • VUID-vkCmdCopyAccelerationStructureToMemoryKHR-pInfo-03741
    If the buffer pointed to by pInfo->dst.deviceAddress is non-sparse then it must be bound completely and contiguously to a single VkDeviceMemory object

  • 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 compute operations

  • VUID-vkCmdCopyAccelerationStructureToMemoryKHR-renderpass
    This command must only be called outside of a render pass instance

Host Synchronization
  • Host access to commandBuffer must be externally synchronized

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

Command Properties
Command Buffer Levels Render Pass Scope Supported Queue Types Pipeline Type




See Also

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 2014-2021 The Khronos Group Inc.

SPDX-License-Identifier: CC-BY-4.0