# VkPartitionedAccelerationStructureUpdateInstanceDataNV(3) Manual Page

## Name

VkPartitionedAccelerationStructureUpdateInstanceDataNV - Structure describing instance data to update in PTLAS

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## C Specification

The VkPartitionedAccelerationStructureUpdateInstanceDataNV structure is defined as:

    // Provided by VK_NV_partitioned_acceleration_structure
    typedef struct VkPartitionedAccelerationStructureUpdateInstanceDataNV {
        uint32_t           instanceIndex;
        uint32_t           instanceContributionToHitGroupIndex;
        VkDeviceAddress    accelerationStructure;
    } VkPartitionedAccelerationStructureUpdateInstanceDataNV;

## Members

- `instanceIndex` is the index of the instance being updated.

- `instanceContributionToHitGroupIndex` is a 24-bit per instance value added in the indexing into the shader binding table to fetch the hit group to use.

- `accelerationStructure` is the device address of the bottom level acceleration structure or a clustered bottom level acceleration structure whose instance is being updated. The instance is disabled if the device address is `0`.

## Description

If the instance was originally disabled by specifying a `0` in VkPartitionedAccelerationStructureWriteInstanceDataNV::`accelerationStructure`, it can not be updated to a new acceleration structure as the instance may have been permanently disabled by the implementation.

To avoid a refit, the new acceleration structure must be within the bounding box specified by VkPartitionedAccelerationStructureWriteInstanceDataNV::`explicitAABB` when the instance was first created.

Valid Usage

- VUID-VkPartitionedAccelerationStructureUpdateInstanceDataNV-instanceContributionToHitGroupIndex-10571
  The most significant 8 bits of `instanceContributionToHitGroupIndex` must be `0`

- VUID-VkPartitionedAccelerationStructureUpdateInstanceDataNV-None-10572
  The instance must have either been created with flag `VK_PARTITIONED_ACCELERATION_STRUCTURE_INSTANCE_FLAG_ENABLE_EXPLICIT_BOUNDING_BOX_NV` or did not have an acceleration structure assigned with VkPartitionedAccelerationStructureWriteInstanceDataNV

- VUID-VkPartitionedAccelerationStructureUpdateInstanceDataNV-instanceIndex-10573
  `instanceIndex` must be less than VkBuildPartitionedAccelerationStructureInfoNV::`input`::`instanceCount`

## See Also

VK_NV_partitioned_acceleration_structure, VkDeviceAddress

## 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 2014-2025 The Khronos Group Inc.

SPDX-License-Identifier: CC-BY-4.0