C Specification

The VkDescriptorMappingSourceShaderRecordIndexEXT structure is defined as:

// Provided by VK_EXT_descriptor_heap
typedef struct VkDescriptorMappingSourceShaderRecordIndexEXT {
    uint32_t                      heapOffset;
    uint32_t                      shaderRecordOffset;
    uint32_t                      heapIndexStride;
    uint32_t                      heapArrayStride;
    const VkSamplerCreateInfo*    pEmbeddedSampler;
    VkBool32                      useCombinedImageSamplerIndex;
    uint32_t                      samplerHeapOffset;
    uint32_t                      samplerShaderRecordOffset;
    uint32_t                      samplerHeapIndexStride;
    uint32_t                      samplerHeapArrayStride;
} VkDescriptorMappingSourceShaderRecordIndexEXT;

Members

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

  • shaderRecordOffset is an index into shader record 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 shader record data.

  • heapArrayStride is a constant byte stride that multiplies the shader binding and array index.

  • 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.

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

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

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

Description

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

shaderRecordIndex = ((uint32_t*)pShaderRecordData)[shaderRecordOffset/4]

shaderIndex = (Binding - firstBinding) + arrayIndex

offset = heapOffset + (shaderRecordIndex × heapIndexStride) + (shaderIndex × heapArrayStride)

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 pShaderRecordData is the set of shader record data accessible to the shader.

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

samplerShaderRecordIndex = ((uint32_t*)pShaderRecordData)[samplerShaderRecordOffset/4]

offset = samplerHeapOffset + (samplerShaderRecordIndex × samplerHeapIndexStride) + (shaderIndex × samplerHeapArrayStride)

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

shaderRecordIndex = ((uint32_t*)pShaderRecordData)[shaderRecordOffset/4] & 0xFFFFF

samplerShaderRecordIndex = (((uint32_t*)pShaderRecordData)[shaderRecordOffset/4] >> 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
Valid Usage (Implicit)

  • VUID-VkDescriptorMappingSourceShaderRecordIndexEXT-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