vkCmdPushDescriptorSetKHR(3)

C Specification

In addition to allocating descriptor sets and binding them to a command buffer, an application can record descriptor updates into the command buffer.

To push descriptor updates into a command buffer, call:

// Provided by VK_KHR_push_descriptor
void vkCmdPushDescriptorSetKHR(
    VkCommandBuffer                             commandBuffer,
    VkPipelineBindPoint                         pipelineBindPoint,
    VkPipelineLayout                            layout,
    uint32_t                                    set,
    uint32_t                                    descriptorWriteCount,
    const VkWriteDescriptorSet*                 pDescriptorWrites);

Parameters

commandBuffer is the command buffer that the descriptors will be recorded in.
pipelineBindPoint is a VkPipelineBindPoint indicating the type of the pipeline that will use the descriptors. There is a separate set of push descriptor bindings for each pipeline type, so binding one does not disturb the others.
layout is a VkPipelineLayout object used to program the bindings.
set is the set number of the descriptor set in the pipeline layout that will be updated.
descriptorWriteCount is the number of elements in the pDescriptorWrites array.
pDescriptorWrites is a pointer to an array of VkWriteDescriptorSet structures describing the descriptors to be updated.

Description

Push descriptors are a small bank of descriptors whose storage is internally managed by the command buffer rather than being written into a descriptor set and later bound to a command buffer. Push descriptors allow for incremental updates of descriptors without managing the lifetime of descriptor sets.

When a command buffer begins recording, all push descriptors are undefined. Push descriptors can be updated incrementally and cause shaders to use the updated descriptors for subsequent bound pipeline commands with the pipeline type set by pipelineBindPoint until the descriptor is overwritten, or else until the set is disturbed as described in Pipeline Layout Compatibility. When the set is disturbed or push descriptors with a different descriptor set layout are set, all push descriptors are undefined.

Push descriptors that are statically used by a pipeline must not be undefined at the time that a drawing or dispatching command is recorded to execute using that pipeline. This includes immutable sampler descriptors, which must be pushed before they are accessed by a pipeline (the immutable samplers are pushed, rather than the samplers in pDescriptorWrites). Push descriptors that are not statically used can remain undefined.

Push descriptors do not use dynamic offsets. Instead, the corresponding non-dynamic descriptor types can be used and the offset member of VkDescriptorBufferInfo can be changed each time the descriptor is written.

Each element of pDescriptorWrites is interpreted as in VkWriteDescriptorSet, except the dstSet member is ignored.

To push an immutable sampler, use a VkWriteDescriptorSet with dstBinding and dstArrayElement selecting the immutable sampler’s binding. If the descriptor type is VK_DESCRIPTOR_TYPE_SAMPLER, the pImageInfo parameter is ignored and the immutable sampler is taken from the push descriptor set layout in the pipeline layout. If the descriptor type is VK_DESCRIPTOR_TYPE_COMBINED_IMAGE_SAMPLER, the sampler member of the pImageInfo parameter is ignored and the immutable sampler is taken from the push descriptor set layout in the pipeline layout.

Valid Usage

VUID-vkCmdPushDescriptorSetKHR-set-00364
set must be less than VkPipelineLayoutCreateInfo::setLayoutCount provided when layout was created
VUID-vkCmdPushDescriptorSetKHR-set-00365
set must be the unique set number in the pipeline layout that uses a descriptor set layout that was created with VK_DESCRIPTOR_SET_LAYOUT_CREATE_PUSH_DESCRIPTOR_BIT_KHR
VUID-vkCmdPushDescriptorSetKHR-pDescriptorWrites-06494
For each element i where pDescriptorWrites[i].descriptorType is VK_DESCRIPTOR_TYPE_SAMPLER, VK_DESCRIPTOR_TYPE_COMBINED_IMAGE_SAMPLER, VK_DESCRIPTOR_TYPE_SAMPLED_IMAGE, VK_DESCRIPTOR_TYPE_STORAGE_IMAGE, or VK_DESCRIPTOR_TYPE_INPUT_ATTACHMENT, pDescriptorWrites[i].pImageInfo must be a valid pointer to an array of pDescriptorWrites[i].descriptorCount valid VkDescriptorImageInfo structures
VUID-vkCmdPushDescriptorSetKHR-pipelineBindPoint-00363
pipelineBindPoint must be supported by the commandBuffer’s parent VkCommandPool’s queue family

Valid Usage (Implicit)

VUID-vkCmdPushDescriptorSetKHR-commandBuffer-parameter
commandBuffer must be a valid VkCommandBuffer handle
VUID-vkCmdPushDescriptorSetKHR-pipelineBindPoint-parameter
pipelineBindPoint must be a valid VkPipelineBindPoint value
VUID-vkCmdPushDescriptorSetKHR-layout-parameter
layout must be a valid VkPipelineLayout handle
VUID-vkCmdPushDescriptorSetKHR-pDescriptorWrites-parameter
pDescriptorWrites must be a valid pointer to an array of descriptorWriteCount valid VkWriteDescriptorSet structures
VUID-vkCmdPushDescriptorSetKHR-commandBuffer-recording
commandBuffer must be in the recording state
VUID-vkCmdPushDescriptorSetKHR-commandBuffer-cmdpool
The VkCommandPool that commandBuffer was allocated from must support graphics, or compute operations
VUID-vkCmdPushDescriptorSetKHR-videocoding
This command must only be called outside of a video coding scope
VUID-vkCmdPushDescriptorSetKHR-descriptorWriteCount-arraylength
descriptorWriteCount must be greater than 0
VUID-vkCmdPushDescriptorSetKHR-commonparent
Both of commandBuffer, and layout must have been created, allocated, or retrieved from the same VkDevice

Host Synchronization

Host access to commandBuffer must be externally synchronized
Host access to the VkCommandPool that commandBuffer was allocated from must be externally synchronized