# VkClusterAccelerationStructureGeometryIndexAndGeometryFlagsNV(3) Manual Page

## Name

VkClusterAccelerationStructureGeometryIndexAndGeometryFlagsNV - Parameters describing geometry index and flags values for cluster acceleration structure

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## C Specification

The VkClusterAccelerationStructureGeometryIndexAndGeometryFlagsNV structure is defined as:

    // Provided by VK_NV_cluster_acceleration_structure
    typedef struct VkClusterAccelerationStructureGeometryIndexAndGeometryFlagsNV {
        uint32_t    geometryIndex:24;
        uint32_t    reserved:5;
        uint32_t    geometryFlags:3;
    } VkClusterAccelerationStructureGeometryIndexAndGeometryFlagsNV;

## Members

- `geometryIndex` specifies the geometry index for all triangles in the cluster acceleration structure.

- `reserved` is reserved for future use.

- `geometryFlags` is a bitmask of VkClusterAccelerationStructureGeometryFlagBitsNV values describing geometry flags for the cluster acceleration structure.

## Description

The C language specification does not define the ordering of bit-fields, but in practice, this structure produces the correct layout with existing compilers. The intended bit pattern is the following:

- `geometryIndex`, `reserved` and `mask` occupy the same memory as if a single `uint32_t` was specified in their place

  - `geometryIndex` occupies the 24 least significant bits of that memory

  - `geometryFlags` occupies the 3 most significant bits of that memory

If a compiler produces code that diverges from that pattern, applications must employ another method to set values according to the correct bit pattern.

Valid Usage

- VUID-VkClusterAccelerationStructureGeometryIndexAndGeometryFlagsNV-reserved-10487
  `reserved` must be `0`

## See Also

VK_NV_cluster_acceleration_structure, VkClusterAccelerationStructureBuildTriangleClusterInfoNV, VkClusterAccelerationStructureBuildTriangleClusterTemplateInfoNV

## 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