# VkClusterAccelerationStructureBuildTriangleClusterTemplateInfoNV(3) Manual Page

## Name

VkClusterAccelerationStructureBuildTriangleClusterTemplateInfoNV - Parameters describing build operation for a template cluster acceleration structure

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## C Specification

The VkClusterAccelerationStructureBuildTriangleClusterTemplateInfoNV structure is defined as:

    // Provided by VK_NV_cluster_acceleration_structure
    typedef struct VkClusterAccelerationStructureBuildTriangleClusterTemplateInfoNV {
        uint32_t                                                         clusterID;
        VkClusterAccelerationStructureClusterFlagsNV                     clusterFlags;
        uint32_t                                                         triangleCount:9;
        uint32_t                                                         vertexCount:9;
        uint32_t                                                         positionTruncateBitCount:6;
        uint32_t                                                         indexType:4;
        uint32_t                                                         opacityMicromapIndexType:4;
        VkClusterAccelerationStructureGeometryIndexAndGeometryFlagsNV    baseGeometryIndexAndGeometryFlags;
        uint16_t                                                         indexBufferStride;
        uint16_t                                                         vertexBufferStride;
        uint16_t                                                         geometryIndexAndFlagsBufferStride;
        uint16_t                                                         opacityMicromapIndexBufferStride;
        VkDeviceAddress                                                  indexBuffer;
        VkDeviceAddress                                                  vertexBuffer;
        VkDeviceAddress                                                  geometryIndexAndFlagsBuffer;
        VkDeviceAddress                                                  opacityMicromapArray;
        VkDeviceAddress                                                  opacityMicromapIndexBuffer;
        VkDeviceAddress                                                  instantiationBoundingBoxLimit;
    } VkClusterAccelerationStructureBuildTriangleClusterTemplateInfoNV;

## Members

- `clusterID` is a user specified identifier assigned to this cluster template.

- `clusterFlags` is a bitmask of VkClusterAccelerationStructureClusterFlagBitsNV values describing flags how the cluster template should be built.

- `triangleCount` is the number of triangles in this cluster.

- `vertexCount` is the number of unique vertices in this cluster.

- `positionTruncateBitCount` is the number of bits starting at the lowest bit (i.e. the LSBs of the mantissa), of each vertex position that will be truncated to zero to improve floating-point compression.

- `indexType` is a single VkClusterAccelerationStructureIndexFormatFlagBitsNV value specifying the index type in `indexBuffer`.

- `opacityMicromapIndexType` is a single VkClusterAccelerationStructureIndexFormatFlagBitsNV value specifying the index type in `opacityMicromapIndexBuffer`.

- `baseGeometryIndexAndGeometryFlags` is a VkClusterAccelerationStructureGeometryIndexAndGeometryFlagsNV value specifying the base geometry index and flags for all triangles in the cluster template.

- `indexBufferStride` is the stride in bytes in `indexBuffer`.

- `vertexBufferStride` is the stride in bytes in `vertexBuffer`.

- `geometryIndexAndFlagsBufferStride` is the stride in bytes in `geometryIndexAndFlagsBuffer`.

- `opacityMicromapIndexBufferStride` is the stride in bytes in `opacityMicromapIndexBuffer`.

- `indexBuffer` contains the indices of vertices in the cluster and is of type `indexType`.

- `vertexBuffer` is either `NULL` or specifies the vertex data of the triangles in the cluster template with format specified in VkClusterAccelerationStructureTriangleClusterInputNV::`vertexFormat`.

- `geometryIndexAndFlagsBuffer` is either `NULL` or an address containing strided VkClusterAccelerationStructureGeometryIndexAndGeometryFlagsNV values specifying the geometry index and flag for every triangle in the cluster.

- `opacityMicromapArray` is either `NULL` or specifies the address of a valid opacity micromap array to reference from the cluster acceleration structure. If it is `NULL`, then opacity micromaps will be disabled for this cluster acceleration structure.

- `opacityMicromapIndexBuffer` is either `NULL` or specifies the address of a strided array with size equal to the number of triangles or indices into the opacity micromap array.

- `instantiationBoundingBoxLimit` is either `NULL` or specifies the address of a bounding box within which all instantiated clusters must lie. The bounding box is specified by six 32-bit floating-point values in the order MinX, MinY, MinZ, MaxX, MaxY, MaxZ.

## 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:

- `triangleCount`, `vertexCount`, `positionTruncateBitCount`, `indexType` and `opacityMicromapIndexType` occupy the same memory as if a single `uint32_t` was specified in their place

  - `triangleCount` occupies the 9 least significant bits of that memory

  - `vertexCount` occupies the next 9 least significant bits of that memory

  - `positionTruncateBitCount` occupies the next 6 least significant bits of that memory

  - `indexType` occupies the next 4 least significant bits of that memory

  - `opacityMicromapIndexType` occupies the 4 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.

Cluster templates cannot be directly used to build bottom level acceleration structures, instead, they must be instantiated into CLAS objects.

Valid Usage

- VUID-VkClusterAccelerationStructureBuildTriangleClusterTemplateInfoNV-clusterID-10497
  `clusterID` must not be 0xFFFFFFFF

- VUID-VkClusterAccelerationStructureBuildTriangleClusterTemplateInfoNV-triangleCount-10498
  `triangleCount` must be less than or equal to VkPhysicalDeviceClusterAccelerationStructurePropertiesNV::`maxTrianglesPerCluster`

- VUID-VkClusterAccelerationStructureBuildTriangleClusterTemplateInfoNV-vertexCount-10499
  `vertexCount` must be less than or equal to VkPhysicalDeviceClusterAccelerationStructurePropertiesNV::`maxVerticesPerCluster`

- VUID-VkClusterAccelerationStructureBuildTriangleClusterTemplateInfoNV-indexType-10500
  `indexType` must only have a single bit set

- VUID-VkClusterAccelerationStructureBuildTriangleClusterTemplateInfoNV-opacityMicromapIndexType-10501
  `opacityMicromapIndexType` must only have a single bit set

- VUID-VkClusterAccelerationStructureBuildTriangleClusterTemplateInfoNV-positionTruncateBitCount-10502
  `positionTruncateBitCount` must be greater than or equal to VkClusterAccelerationStructureTriangleClusterInputNV::`minPositionTruncateBitCount` and less than or equal to `32`

- VUID-VkClusterAccelerationStructureBuildTriangleClusterTemplateInfoNV-indexBufferStride-10503
  `indexBufferStride` must be `0` or a multiple of `indexType`

- VUID-VkClusterAccelerationStructureBuildTriangleClusterTemplateInfoNV-vertexBufferStride-10504
  `vertexBufferStride` must be `0` or a multiple of value specified in VkClusterAccelerationStructureTriangleClusterInputNV::`vertexFormat`

- VUID-VkClusterAccelerationStructureBuildTriangleClusterTemplateInfoNV-instantiationBoundingBoxLimit-10505
  `instantiationBoundingBoxLimit` must be aligned to VkPhysicalDeviceClusterAccelerationStructurePropertiesNV::`clusterTemplateBoundsByteAlignment`

- VUID-VkClusterAccelerationStructureBuildTriangleClusterTemplateInfoNV-baseGeometryIndex-10506
  The maximum geometry index after using the values in `baseGeometryIndex` and `geometryIndexBuffer` must be less than VkPhysicalDeviceClusterAccelerationStructurePropertiesNV::`maxClusterGeometryIndex`

Valid Usage (Implicit)

- VUID-VkClusterAccelerationStructureBuildTriangleClusterTemplateInfoNV-clusterFlags-parameter
  `clusterFlags` must be a valid combination of VkClusterAccelerationStructureClusterFlagBitsNV values

## See Also

VK_NV_cluster_acceleration_structure, VkClusterAccelerationStructureClusterFlagsNV, VkClusterAccelerationStructureGeometryIndexAndGeometryFlagsNV, 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