vkCreateDescriptorUpdateTemplate

Updating a large VkDescriptorSet array can be an expensive operation since an application must specify one VkWriteDescriptorSet structure for each descriptor or descriptor array to update, each of which re-specifies the same state when updating the same descriptor in multiple descriptor sets. For cases when an application wishes to update the same set of descriptors in multiple descriptor sets allocated using the same VkDescriptorSetLayout, vkUpdateDescriptorSetWithTemplate can be used as a replacement for vkUpdateDescriptorSets.

VkDescriptorUpdateTemplate allows implementations to convert a set of descriptor update operations on a single descriptor set to an internal format. In conjunction with vkCmdPushDescriptorSetWithTemplate or vkUpdateDescriptorSetWithTemplate, this can be more efficient compared to calling vkCmdPushDescriptorSet or vkUpdateDescriptorSets. The descriptors themselves are not specified in the VkDescriptorUpdateTemplate, rather, offsets into an application provided pointer to host memory are specified, which are combined with a pointer passed to vkCmdPushDescriptorSetWithTemplate or vkUpdateDescriptorSetWithTemplate. This allows large batches of updates to be executed without having to convert application data structures into a strictly-defined Vulkan data structure.

To create a descriptor update template, call:

VkResult vkCreateDescriptorUpdateTemplateKHR(
    VkDevice device,
    const VkDescriptorUpdateTemplateCreateInfo* pCreateInfo,
    const VkAllocationCallbacks* pAllocator,
    VkDescriptorUpdateTemplate* pDescriptorUpdateTemplate);

• device is the logical device that creates the descriptor update template.
• pCreateInfo is a pointer to a VkDescriptorUpdateTemplateCreateInfo structure specifying the set of descriptors to update with a single call to vkCmdPushDescriptorSetWithTemplate or vkUpdateDescriptorSetWithTemplate.
• pAllocator controls host memory allocation as described in the Memory Allocation chapter.
• pDescriptorUpdateTemplate is a pointer to a VkDescriptorUpdateTemplate handle in which the resulting descriptor update template object is returned.