vkCmdPushDescriptorSet

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:

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

• 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.

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.