Package org.lwjgl.vulkan

Class VkDescriptorPoolCreateInfo

java.lang.Object
org.lwjgl.system.Pointer.Default
org.lwjgl.system.Struct<VkDescriptorPoolCreateInfo>
org.lwjgl.vulkan.VkDescriptorPoolCreateInfo
All Implemented Interfaces:
AutoCloseable, org.lwjgl.system.NativeResource, org.lwjgl.system.Pointer
public class VkDescriptorPoolCreateInfo extends org.lwjgl.system.Struct<VkDescriptorPoolCreateInfo> implements org.lwjgl.system.NativeResource
Structure specifying parameters of a newly created descriptor pool.
Description

If multiple VkDescriptorPoolSize structures containing the same descriptor type appear in the pPoolSizes array then the pool will be created with enough storage for the total number of descriptors of each type.

Fragmentation of a descriptor pool is possible and may lead to descriptor set allocation failures. A failure due to fragmentation is defined as failing a descriptor set allocation despite the sum of all outstanding descriptor set allocations from the pool plus the requested allocation requiring no more than the total number of descriptors requested at pool creation. Implementations provide certain guarantees of when fragmentation must not cause allocation failure, as described below.

If a descriptor pool has not had any descriptor sets freed since it was created or most recently reset then fragmentation must not cause an allocation failure (note that this is always the case for a pool created without the DESCRIPTOR_POOL_CREATE_FREE_DESCRIPTOR_SET_BIT bit set). Additionally, if all sets allocated from the pool since it was created or most recently reset use the same number of descriptors (of each type) and the requested allocation also uses that same number of descriptors (of each type), then fragmentation must not cause an allocation failure.

If an allocation failure occurs due to fragmentation, an application can create an additional descriptor pool to perform further descriptor set allocations.

If flags has the DESCRIPTOR_POOL_CREATE_UPDATE_AFTER_BIND_BIT bit set, descriptor pool creation may fail with the error ERROR_FRAGMENTATION if the total number of descriptors across all pools (including this one) created with this bit set exceeds maxUpdateAfterBindDescriptorsInAllPools, or if fragmentation of the underlying hardware resources occurs.

If a pPoolSizes[i]::type is DESCRIPTOR_TYPE_MUTABLE_EXT, a VkMutableDescriptorTypeCreateInfoEXT struct in the pNext chain can be used to specify which mutable descriptor types can be allocated from the pool. If included in the pNext chain, VkMutableDescriptorTypeCreateInfoEXT::pMutableDescriptorTypeLists[i] specifies which kind of DESCRIPTOR_TYPE_MUTABLE_EXT descriptors can be allocated from this pool entry. If VkMutableDescriptorTypeCreateInfoEXT does not exist in the pNext chain, or VkMutableDescriptorTypeCreateInfoEXT::pMutableDescriptorTypeLists[i] is out of range, the descriptor pool allocates enough memory to be able to allocate a DESCRIPTOR_TYPE_MUTABLE_EXT descriptor with any supported VkDescriptorType as a mutable descriptor. A mutable descriptor can be allocated from a pool entry if the type list in VkDescriptorSetLayoutCreateInfo is a subset of the type list declared in the descriptor pool, or if the pool entry is created without a descriptor type list. Multiple pPoolSizes entries with DESCRIPTOR_TYPE_MUTABLE_EXT can be declared. When multiple such pool entries are present in pPoolSizes, they specify sets of supported descriptor types which either fully overlap, partially overlap, or are disjoint. Two sets fully overlap if the sets of supported descriptor types are equal. If the sets are not disjoint they partially overlap. A pool entry without a VkMutableDescriptorTypeListEXT assigned to it is considered to partially overlap any other pool entry which has a VkMutableDescriptorTypeListEXT assigned to it. The application must ensure that partial overlap does not exist in pPoolSizes.

Note

The requirement of no partial overlap is intended to resolve ambiguity for validation as there is no confusion which pPoolSizes entries will be allocated from. An implementation is not expected to depend on this requirement.

Valid Usage
Valid Usage (Implicit)
See Also

VkDescriptorPoolSize, CreateDescriptorPool

Layout


 struct VkDescriptorPoolCreateInfo {
     VkStructureType sType();
     void const * pNext();
     VkDescriptorPoolCreateFlags flags();
     uint32_t maxSets();
     uint32_t poolSizeCount();
     VkDescriptorPoolSize const * pPoolSizes();
 }