# VkAccelerationStructureTrianglesDisplacementMicromapNV(3) Manual Page

## Name

VkAccelerationStructureTrianglesDisplacementMicromapNV - Structure specifying a displacement micromap in a bottom-level acceleration structure

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## C Specification

The `VkAccelerationStructureTrianglesDisplacementMicromapNV` structure is defined as:

    // Provided by VK_NV_displacement_micromap
    typedef struct VkAccelerationStructureTrianglesDisplacementMicromapNV {
        VkStructureType                     sType;
        void*                               pNext;
        VkFormat                            displacementBiasAndScaleFormat;
        VkFormat                            displacementVectorFormat;
        VkDeviceOrHostAddressConstKHR       displacementBiasAndScaleBuffer;
        VkDeviceSize                        displacementBiasAndScaleStride;
        VkDeviceOrHostAddressConstKHR       displacementVectorBuffer;
        VkDeviceSize                        displacementVectorStride;
        VkDeviceOrHostAddressConstKHR       displacedMicromapPrimitiveFlags;
        VkDeviceSize                        displacedMicromapPrimitiveFlagsStride;
        VkIndexType                         indexType;
        VkDeviceOrHostAddressConstKHR       indexBuffer;
        VkDeviceSize                        indexStride;
        uint32_t                            baseTriangle;
        uint32_t                            usageCountsCount;
        const VkMicromapUsageEXT*           pUsageCounts;
        const VkMicromapUsageEXT* const*    ppUsageCounts;
        VkMicromapEXT                       micromap;
    } VkAccelerationStructureTrianglesDisplacementMicromapNV;

## Members

- `sType` is a VkStructureType value identifying this structure.

- `pNext` is `NULL` or a pointer to a structure extending this structure.

- `displacementBiasAndScaleFormat` is the format of displacement bias and scale used in this displacement micromap reference.

- `displacementVectorFormat` is the format of displacement vector used in this displacement micromap reference.

- `displacementBiasAndScaleBuffer` is the address containing the bias and scale.

- `displacementBiasAndScaleStride` is the byte stride between bias and scale values.

- `displacementVectorBuffer` is the address containing the displacement vector values.

- `displacementVectorStride` is the byte stride between displacement vector values.

- `displacedMicromapPrimitiveFlags` is the address containing the primitive flags.

- `displacedMicromapPrimitiveFlagsStride` is the byte stride between primitive flag values.

- `indexType` is the type of triangle indices used when indexing this micromap.

- `indexBuffer` is the address containing the triangle indices.

- `indexStride` is the byte stride between triangle indices.

- `baseTriangle` is the base value added to the non-negative triangle indices.

- `usageCountsCount` specifies the number of usage counts structures that will be used to determine the size of this micromap.

- `pUsageCounts` is a pointer to an array of VkMicromapUsageEXT structures.

- `ppUsageCounts` is a pointer to an array of pointers to VkMicromapUsageEXT structures.

- `micromap` is the handle to the micromap object to include in this geometry.

## Description

If `VkAccelerationStructureTrianglesDisplacementMicromapNV` is included in the `pNext` chain of a VkAccelerationStructureGeometryTrianglesDataKHR structure, that geometry will reference that micromap.

For each triangle in the geometry, the acceleration structure build fetches an index from `indexBuffer` using `indexType` and `indexStride`. That triangle uses the displacement micromap information from `micromap` at that index plus `baseTriangle`.

Only one of `pUsageCounts` or `ppUsageCounts` can be a valid pointer, the other must be `NULL`. The elements of the non-`NULL` array describe the total count used to build this geometry. For a given `format` and `subdivisionLevel` the number of triangles in this geometry matching those values after indirection must be equal to the sum of matching `count` provided.

Valid Usage

- VUID-VkAccelerationStructureTrianglesDisplacementMicromapNV-displacementBiasAndScaleFormat-09501
  `displacementBiasAndScaleFormat` must not be `VK_FORMAT_UNDEFINED`

- VUID-VkAccelerationStructureTrianglesDisplacementMicromapNV-displacementVectorFormat-09502
  `displacementVectorFormat` must not be `VK_FORMAT_UNDEFINED`

- VUID-VkAccelerationStructureTrianglesDisplacementMicromapNV-pUsageCounts-07992
  Only one of `pUsageCounts` or `ppUsageCounts` can be a valid pointer, the other must be `NULL`

Valid Usage (Implicit)

- VUID-VkAccelerationStructureTrianglesDisplacementMicromapNV-sType-sType
  `sType` must be `VK_STRUCTURE_TYPE_ACCELERATION_STRUCTURE_TRIANGLES_DISPLACEMENT_MICROMAP_NV`

- VUID-VkAccelerationStructureTrianglesDisplacementMicromapNV-displacementBiasAndScaleFormat-parameter
  `displacementBiasAndScaleFormat` must be a valid VkFormat value

- VUID-VkAccelerationStructureTrianglesDisplacementMicromapNV-displacementVectorFormat-parameter
  `displacementVectorFormat` must be a valid VkFormat value

- VUID-VkAccelerationStructureTrianglesDisplacementMicromapNV-indexType-parameter
  `indexType` must be a valid VkIndexType value

- VUID-VkAccelerationStructureTrianglesDisplacementMicromapNV-pUsageCounts-parameter
  If `usageCountsCount` is not `0`, and `pUsageCounts` is not `NULL`, `pUsageCounts` must be a valid pointer to an array of `usageCountsCount` VkMicromapUsageEXT structures

- VUID-VkAccelerationStructureTrianglesDisplacementMicromapNV-ppUsageCounts-parameter
  If `usageCountsCount` is not `0`, and `ppUsageCounts` is not `NULL`, `ppUsageCounts` must be a valid pointer to an array of `usageCountsCount` valid pointers to VkMicromapUsageEXT structures

- VUID-VkAccelerationStructureTrianglesDisplacementMicromapNV-micromap-parameter
  If `micromap` is not VK_NULL_HANDLE, `micromap` must be a valid VkMicromapEXT handle

## See Also

VK_NV_displacement_micromap, VkDeviceOrHostAddressConstKHR, VkDeviceSize, VkFormat, VkIndexType, VkMicromapEXT, VkMicromapUsageEXT, VkStructureType

## 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 2014-2024 The Khronos Group Inc.

SPDX-License-Identifier: CC-BY-4.0