C Specification

The VkDescriptorMappingSourceIndirectIndexArrayEXT structure is defined as:

// Provided by VK_EXT_descriptor_heap
typedef struct VkDescriptorMappingSourceIndirectIndexArrayEXT {
    uint32_t                      heapOffset;
    uint32_t                      pushOffset;
    uint32_t                      addressOffset;
    uint32_t                      heapIndexStride;
    const VkSamplerCreateInfo*    pEmbeddedSampler;
    VkBool32                      useCombinedImageSamplerIndex;
    uint32_t                      samplerHeapOffset;
    uint32_t                      samplerPushOffset;
    uint32_t                      samplerAddressOffset;
    uint32_t                      samplerHeapIndexStride;
} VkDescriptorMappingSourceIndirectIndexArrayEXT;

Members

  • heapOffset is a constant byte offset added to the heap address for the mapped resource or sampler.

  • pushOffset is an offset into push data where an the indirect address will be.

  • addressOffset is an index into the address in push data where an index into the heap for the mapped resource will be retrieved.

  • heapIndexStride is a constant byte stride that multiplies the index in indirect data.

  • pEmbeddedSampler is an optional VkSamplerCreateInfo structure specifying a sampler to embed into the shader, in place of looking the sampler up in a heap.

  • useCombinedImageSamplerIndex specifies whether the generated index value will be decoded as two packed indices if the mapped resource is an OpTypeSampledImage.

  • samplerHeapOffset is used only when mapping a combined image sampler, used in place of heapOffset to retrieve the sampler.

  • samplerPushOffset is used only when mapping a combined image sampler, used in place of pushOffset to retrieve the sampler.

  • samplerAddressOffset is used only when mapping a combined image sampler, used in place of addressOffset to retrieve the sampler.

  • samplerHeapIndexStride is used only when mapping a combined image sampler, used in place of heapIndexStride to retrieve the sampler.

Description

Resources using this mapping will be backed by a descriptor in the heap, at an offset calculated as

uint32_t *indirectAddress = ((VkDeviceAddress*)pPushData)[pushOffset/8]

shaderIndex = (Binding - firstBinding) + arrayIndex

indirectIndex = indirectAddress[(addressOffset / 4) + shaderIndex]

offset = heapOffset + (indirectIndex × heapIndexStride)

where Binding is the binding value in the shader, arrayIndex is the index into the array if the shader binding is declared as an array, and pPushData is the total set of push data specified by vkCmdPushDataEXT. The value of the address in push data must be a multiple of 4. Index reads through indirectAddress are performed as non-volatile uniform buffer reads, and can be synchronized using VK_ACCESS_2_UNIFORM_READ_BIT. The value in memory must remain static while any shader invocation using this mapping is in flight to avoid a data race.

If the mapped resource is a OpTypeSampledImage, offset is instead calculated for the sampler as

uint32_t *samplerIndirectAddress = ((VkDeviceAddress*)pPushData)[samplerPushOffset/8]

samplerIndirectIndex = samplerAddr[(samplerAddressOffset / 4) + shaderIndex]

offset = samplerHeapOffset + (samplerIndirectIndex × samplerHeapIndexStride)

If useCombinedImageSamplerIndex is VK_TRUE, and the mapped resource is a OpTypeSampledImage, indirectIndex and samplerIndirectIndex in the above equations are instead calculated as

indirectIndex = indirectAddress[addressOffset/4 + shaderIndex] & 0xFFFFF

samplerIndirectIndex = indirectAddress[addressOffset/4 + shaderIndex] >> 20) & 0xFFF

If the mapped resource is a OpTypeSampler or OpTypeSampledImage, and pEmbeddedSampler is not NULL, the specified embedded sampler will be used rather than accessing the sampler heap.

Valid Usage

  • VUID-VkDescriptorMappingSourceIndirectIndexArrayEXT-pushOffset-11359
    pushOffset must be a multiple of 8

  • VUID-VkDescriptorMappingSourceIndirectIndexArrayEXT-pushOffset-11360
    pushOffset must be less than or equal to maxPushDataSize - 8

  • VUID-VkDescriptorMappingSourceIndirectIndexArrayEXT-addressOffset-11361
    addressOffset must be a multiple of 4

  • VUID-VkDescriptorMappingSourceIndirectIndexArrayEXT-pEmbeddedSampler-11448
    If pEmbeddedSampler is a valid pointer to a VkSamplerCreateInfo, its borderColor must not be VK_BORDER_COLOR_FLOAT_CUSTOM_EXT or VK_BORDER_COLOR_INT_CUSTOM_EXT

  • VUID-VkDescriptorMappingSourceIndirectIndexArrayEXT-pEmbeddedSampler-11404
    If pEmbeddedSampler is a valid pointer to a VkSamplerCreateInfo, and there is a VkDebugUtilsObjectNameInfoEXT structure in its pNext chain, its objectType must be VK_OBJECT_TYPE_UNKNOWN

Valid Usage (Implicit)

  • VUID-VkDescriptorMappingSourceIndirectIndexArrayEXT-pEmbeddedSampler-parameter
    If pEmbeddedSampler is not NULL, pEmbeddedSampler must be a valid pointer to a valid VkSamplerCreateInfo structure

See Also

VK_EXT_descriptor_heap, VkBool32, VkDescriptorMappingSourceDataEXT, VkSamplerCreateInfo

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 2014-2026 The Khronos Group Inc.

SPDX-License-Identifier: CC-BY-4.0