VkPresentIdKHR

The VkPresentIdKHR structure is defined as:

typedef struct VkPresentIdKHR {
    VkStructureType sType;
    const void* pNext;
    uint32_t swapchainCount;
    const uint64_t* pPresentIds;
} VkPresentIdKHR;

• sType is a VkStructureType value identifying this structure.
• pNext is NULL or a pointer to a structure extending this structure.
• swapchainCount is the number of swapchains being presented to the vkQueuePresentKHR command.
• pPresentIds is NULL or a pointer to an array of uint64_t with swapchainCount entries. If not NULL, each non-zero value in pPresentIds specifies the present id to be associated with the presentation of the swapchain with the same index in the vkQueuePresentKHR call.

For applications to be able to reference specific presentation events queued by a call to vkQueuePresentKHR, an identifier needs to be associated with them. When the presentId feature is enabled, applications can include the VkPresentIdKHR structure in the pNext chain of the VkPresentInfoKHR structure to supply identifiers.

Each VkSwapchainKHR has a presentId associated with it. This value is initially zero when the VkSwapchainKHR is created.

When a VkPresentIdKHR structure with a non-NULL pPresentIds is included in the pNext chain of a VkPresentInfoKHR structure, each pSwapchains entry has a presentId associated in the pPresentIds array at the same index as the swapchain in the pSwapchains array. If this presentId is non-zero, then the application can later use this value to refer to that image presentation. A value of zero indicates that this presentation has no associated presentId. A non-zero presentId must be greater than any non-zero presentId passed previously by the application for the same swapchain.

There is no requirement for any precise timing relationship between the presentation of the image to the user and the update of the presentId value, but implementations should make this as close as possible to the presentation of the first pixel in the new image to the user.