C Specification

The VkAccelerationStructureTrianglesOpacityMicromapEXT structure is defined as:

// Provided by VK_EXT_opacity_micromap
typedef struct VkAccelerationStructureTrianglesOpacityMicromapEXT {
    VkStructureType                     sType;
    void*                               pNext;
    VkIndexType                         indexType;
    VkDeviceOrHostAddressConstKHR       indexBuffer;
    VkDeviceSize                        indexStride;
    uint32_t                            baseTriangle;
    uint32_t                            usageCountsCount;
    const VkMicromapUsageEXT*           pUsageCounts;
    const VkMicromapUsageEXT* const*    ppUsageCounts;
    VkMicromapEXT                       micromap;
} VkAccelerationStructureTrianglesOpacityMicromapEXT;


  • sType is the type of this structure.

  • pNext is NULL or a pointer to a structure extending this structure.

  • 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


If VkAccelerationStructureTrianglesOpacityMicromapEXT 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. If that value is the unsigned cast of one of the values from VkOpacityMicromapSpecialIndexEXT then that triangle behaves as described for that special value in Ray Opacity Micromap. Otherwise that triangle uses the opacity 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 and special index handling must be equal to the sum of matching count provided.

If micromap is VK_NULL_HANDLE, then every value read from indexBuffer must be one of the values in VkOpacityMicromapSpecialIndexEXT.

Valid Usage
  • VUID-VkAccelerationStructureTrianglesOpacityMicromapEXT-pUsageCounts-07335
    Only one of pUsageCounts or ppUsageCounts can be a valid pointer, the other must be NULL

Valid Usage (Implicit)
  • VUID-VkAccelerationStructureTrianglesOpacityMicromapEXT-sType-sType

  • VUID-VkAccelerationStructureTrianglesOpacityMicromapEXT-indexType-parameter
    indexType must be a valid VkIndexType value

  • VUID-VkAccelerationStructureTrianglesOpacityMicromapEXT-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-VkAccelerationStructureTrianglesOpacityMicromapEXT-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-VkAccelerationStructureTrianglesOpacityMicromapEXT-micromap-parameter
    If micromap is not VK_NULL_HANDLE, micromap must be a valid VkMicromapEXT handle

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 2014-2023 The Khronos Group Inc.

SPDX-License-Identifier: CC-BY-4.0