# VkDescriptorSetVariableDescriptorCountLayoutSupport(3) Manual Page

## Name

VkDescriptorSetVariableDescriptorCountLayoutSupport - Structure returning information about whether a descriptor set layout can be supported

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## C Specification

If the `pNext` chain of a VkDescriptorSetLayoutSupport structure includes a `VkDescriptorSetVariableDescriptorCountLayoutSupport` structure, then that structure returns additional information about whether the descriptor set layout is supported.

    // Provided by VK_VERSION_1_2
    typedef struct VkDescriptorSetVariableDescriptorCountLayoutSupport {
        VkStructureType    sType;
        void*              pNext;
        uint32_t           maxVariableDescriptorCount;
    } VkDescriptorSetVariableDescriptorCountLayoutSupport;

or the equivalent

    // Provided by VK_EXT_descriptor_indexing
    typedef VkDescriptorSetVariableDescriptorCountLayoutSupport VkDescriptorSetVariableDescriptorCountLayoutSupportEXT;

## Members

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

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

- `maxVariableDescriptorCount` indicates the maximum number of descriptors supported in the highest numbered binding of the layout, if that binding is variable-sized. If the highest numbered binding of the layout has a descriptor type of `VK_DESCRIPTOR_TYPE_INLINE_UNIFORM_BLOCK` then `maxVariableDescriptorCount` indicates the maximum byte size supported for the binding, if that binding is variable-sized.

## Description

If the VkDescriptorSetLayoutCreateInfo structure specified in vkGetDescriptorSetLayoutSupport::`pCreateInfo` includes a variable-sized descriptor, then `supported` is determined assuming the requested size of the variable-sized descriptor, and `maxVariableDescriptorCount` is the maximum size of that descriptor that can be successfully created (which is greater than or equal to the requested size passed in). If the VkDescriptorSetLayoutCreateInfo structure does not include a variable-sized descriptor, or if the VkPhysicalDeviceDescriptorIndexingFeatures::`descriptorBindingVariableDescriptorCount` feature is not enabled, then `maxVariableDescriptorCount` is zero. For the purposes of this command, a variable-sized descriptor binding with a `descriptorCount` of zero is treated as having a `descriptorCount` of four if `descriptorType` is `VK_DESCRIPTOR_TYPE_INLINE_UNIFORM_BLOCK`, or one otherwise, and thus the binding is not ignored and the maximum descriptor count will be returned. If the layout is not supported, then the value written to `maxVariableDescriptorCount` is undefined.

Valid Usage (Implicit)

- VUID-VkDescriptorSetVariableDescriptorCountLayoutSupport-sType-sType
  `sType` must be `VK_STRUCTURE_TYPE_DESCRIPTOR_SET_VARIABLE_DESCRIPTOR_COUNT_LAYOUT_SUPPORT`

## See Also

VK_EXT_descriptor_indexing, VK_VERSION_1_2, 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 2014-2025 The Khronos Group Inc.

SPDX-License-Identifier: CC-BY-4.0