C Specification

To allocate descriptor sets from a descriptor pool, call:

VkResult vkAllocateDescriptorSets(
    VkDevice                                    device,
    const VkDescriptorSetAllocateInfo*          pAllocateInfo,
    VkDescriptorSet*                            pDescriptorSets);

Parameters

  • device is the logical device that owns the descriptor pool.

  • pAllocateInfo is a pointer to a VkDescriptorSetAllocateInfo structure describing parameters of the allocation.

  • pDescriptorSets is a pointer to an array of VkDescriptorSet handles in which the resulting descriptor set objects are returned.

Description

The allocated descriptor sets are returned in pDescriptorSets.

When a descriptor set is allocated, the initial state is largely uninitialized and all descriptors are undefined. Descriptors also become undefined if the underlying resource is destroyed. Descriptor sets containing undefined descriptors can still be bound and used, subject to the following conditions:

  • For descriptor set bindings created with the VK_DESCRIPTOR_BINDING_PARTIALLY_BOUND_BIT_EXT bit set, all descriptors in that binding that are dynamically used must have been populated before the descriptor set is consumed.

  • For descriptor set bindings created without the VK_DESCRIPTOR_BINDING_PARTIALLY_BOUND_BIT_EXT bit set, all descriptors in that binding that are statically used must have been populated before the descriptor set is consumed.

  • Descriptor bindings with descriptor type of VK_DESCRIPTOR_TYPE_INLINE_UNIFORM_BLOCK_EXT can be undefined when the descriptor set is consumed; though values in that block will be undefined.

  • Entries that are not used by a pipeline can have undefined descriptors.

If a call to vkAllocateDescriptorSets would cause the total number of descriptor sets allocated from the pool to exceed the value of VkDescriptorPoolCreateInfo::maxSets used to create pAllocateInfo->descriptorPool, then the allocation may fail due to lack of space in the descriptor pool. Similarly, the allocation may fail due to lack of space if the call to vkAllocateDescriptorSets would cause the number of any given descriptor type to exceed the sum of all the descriptorCount members of each element of VkDescriptorPoolCreateInfo::pPoolSizes with a member equal to that type.

Additionally, the allocation may also fail if a call to vkAllocateDescriptorSets would cause the total number of inline uniform block bindings allocated from the pool to exceed the value of VkDescriptorPoolInlineUniformBlockCreateInfoEXT::maxInlineUniformBlockBindings used to create the descriptor pool.

If the allocation fails due to no more space in the descriptor pool, and not because of system or device memory exhaustion, then VK_ERROR_OUT_OF_POOL_MEMORY must be returned.

vkAllocateDescriptorSets can be used to create multiple descriptor sets. If the creation of any of those descriptor sets fails, then the implementation must destroy all successfully created descriptor set objects from this command, set all entries of the pDescriptorSets array to VK_NULL_HANDLE and return the error.

Valid Usage (Implicit)
  • device must be a valid VkDevice handle

  • pAllocateInfo must be a valid pointer to a valid VkDescriptorSetAllocateInfo structure

  • pDescriptorSets must be a valid pointer to an array of pAllocateInfo::descriptorSetCount VkDescriptorSet handles

  • The value referenced by pAllocateInfo::descriptorSetCount must be greater than 0

Host Synchronization
  • Host access to pAllocateInfo::descriptorPool must be externally synchronized

Return Codes
On success, this command returns
  • VK_SUCCESS

On failure, this command returns
  • VK_ERROR_OUT_OF_HOST_MEMORY

  • VK_ERROR_OUT_OF_DEVICE_MEMORY

  • VK_ERROR_FRAGMENTED_POOL

  • VK_ERROR_OUT_OF_POOL_MEMORY

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 (c) 2014-2019 Khronos Group. This work is licensed under a Creative Commons Attribution 4.0 International License.