// Copyright (c) 2014-2017 The Khronos Group Inc. // Copyright notice at https://www.khronos.org/registry/speccopyright.html == WSI Swapchain // refBegin VkSwapchainKHR - Opaque handle to a swapchain object A swapchain object (a.k.a. swapchain) provides the ability to present rendering results to a surface. Swapchain objects are represented by sname:VkSwapchainKHR handles: include::../../api/handles/VkSwapchainKHR.txt[] A swapchain is an abstraction for an array of presentable images that are associated with a surface. The presentable images are represented by sname:VkImage objects created by the platform. One image (which can: be an array image for multiview/stereoscopic-3D surfaces) is displayed at a time, but multiple images can: be queued for presentation. An application renders to the image, and then queues the image for presentation to the surface. A native window cannot: be associated with more than one swapchain at a time. Further, swapchains cannot: be created for native windows that have a non-Vulkan graphics API surface associated with them. The presentation engine is an abstraction for the platform's compositor or hardware/software display engine. [NOTE] .Note ==== The presentation engine may: be synchronous or asynchronous with respect to the application and/or logical device. Some implementations may: use the device's graphics queue or dedicated presentation hardware to perform presentation. ==== The presentable images of a swapchain are owned by the presentation engine. An application can: acquire use of a presentable image from the presentation engine. Use of a presentable image must: occur only after the image is returned by fname:vkAcquireNextImageKHR, and before it is presented by fname:vkQueuePresentKHR. This includes transitioning the image layout and rendering commands. An application can: acquire use of a presentable image with fname:vkAcquireNextImageKHR. After acquiring a presentable image and before modifying it, the application must: use a synchronization primitive to ensure that the presentation engine has finished reading from the image. The application can: then transition the image's layout, queue rendering commands to it, etc. Finally, the application presents the image with fname:vkQueuePresentKHR, which releases the acquisition of the image. The presentation engine controls the order in which presentable images are acquired for use by the application. [NOTE] .Note ==== This allows the platform to handle situations which require out-of-order return of images after presentation. At the same time, it allows the application to generate command buffers referencing all of the images in the swapchain at initialization time, rather than in its main loop. ==== // refEnd VkSwapchainKHR How this all works is described below. ifdef::VK_KHR_shared_presentable_image[] include::../VK_KHR_shared_presentable_image/wsi.txt[] endif::VK_KHR_shared_presentable_image[] // refBegin vkCreateSwapchainKHR - Create a swapchain To create a swapchain, call: include::../../api/protos/vkCreateSwapchainKHR.txt[] * pname:device is the device to create the swapchain for. * pname:pCreateInfo is a pointer to an instance of the slink:VkSwapchainCreateInfoKHR structure specifying the parameters of the created swapchain. * pname:pAllocator is the allocator used for host memory allocated for the swapchain object when there is no more specific allocator available (see <>). * pname:pSwapchain is a pointer to a sname:VkSwapchainKHR handle in which the created swapchain object will be returned. include::../../validity/protos/vkCreateSwapchainKHR.txt[] // refBegin VkSwapchainCreateInfoKHR - Structure specifying parameters of a newly created swapchain object The sname:VkSwapchainCreateInfoKHR structure is defined as: include::../../api/structs/VkSwapchainCreateInfoKHR.txt[] * pname:sType is the type of this structure. * pname:pNext is `NULL` or a pointer to an extension-specific structure. * pname:flags is a bitmask of elink:VkSwapchainCreateFlagBitsKHR indicating parameters of swapchain creation. * pname:surface is the surface that the swapchain will present images to. * pname:minImageCount is the minimum number of presentable images that the application needs. The platform will either create the swapchain with at least that many images, or will fail to create the swapchain. * pname:imageFormat is a slink:VkFormat that is valid for swapchains on the specified surface. * pname:imageColorSpace is a slink:VkColorSpaceKHR that is valid for swapchains on the specified surface. * pname:imageExtent is the size (in pixels) of the swapchain. Behavior is platform-dependent when the image extent does not match the surface's pname:currentExtent as returned by fname:vkGetPhysicalDeviceSurfaceCapabilitiesKHR. * pname:imageArrayLayers is the number of views in a multiview/stereo surface. For non-stereoscopic-3D applications, this value is 1. * pname:imageUsage is a bitmask of elink:VkImageUsageFlagBits, indicating how the application will use the swapchain's presentable images. * pname:imageSharingMode is the sharing mode used for the images of the swapchain. * pname:queueFamilyIndexCount is the number of queue families having access to the images of the swapchain in case pname:imageSharingMode is ename:VK_SHARING_MODE_CONCURRENT. * pname:pQueueFamilyIndices is an array of queue family indices having access to the images of the swapchain in case pname:imageSharingMode is ename:VK_SHARING_MODE_CONCURRENT. * pname:preTransform is a bitmask of elink:VkSurfaceTransformFlagBitsKHR, describing the transform, relative to the presentation engine's natural orientation, applied to the image content prior to presentation. If it does not match the pname:currentTransform value returned by fname:vkGetPhysicalDeviceSurfaceCapabilitiesKHR, the presentation engine will transform the image content as part of the presentation operation. * pname:compositeAlpha is a bitmask of elink:VkCompositeAlphaFlagBitsKHR indicating the alpha compositing mode to use when this surface is composited together with other surfaces on certain window systems. * pname:presentMode is the presentation mode the swapchain will use. A swapchain's present mode determines how incoming present requests will be processed and queued internally. * pname:clipped indicates whether the Vulkan implementation is allowed to discard rendering operations that affect regions of the surface which are not visible. ** If set to ename:VK_TRUE, the presentable images associated with the swapchain may: not own all of their pixels. Pixels in the presentable images that correspond to regions of the target surface obscured by another window on the desktop or subject to some other clipping mechanism will have undefined content when read back. Pixel shaders may: not execute for these pixels, and thus any side affects they would have had will not occur. ** If set to ename:VK_FALSE, presentable images associated with the swapchain will own all the pixels they contain. Setting this value to ename:VK_TRUE does not guarantee any clipping will occur, but allows more optimal presentation methods to be used on some platforms. [NOTE] .Note ==== Applications should: set this value to ename:VK_TRUE if they do not expect to read back the content of presentable images before presenting them or after reacquiring them and if their pixel shaders do not have any side effects that require them to run for all pixels in the presentable image. ==== * pname:oldSwapchain, if not dlink:VK_NULL_HANDLE, specifies the swapchain that will be replaced by the new swapchain being created. The new swapchain will be a descendant of pname:oldSwapchain. Further, any descendants of the new swapchain will also be descendants of pname:oldSwapchain. Upon calling fname:vkCreateSwapchainKHR with a pname:oldSwapchain that is not dlink:VK_NULL_HANDLE, any images not acquired by the application may: be freed by the implementation, which may: occur even if creation of the new swapchain fails. The application must: destroy the old swapchain to free all memory associated with the old swapchain. The application must: wait for the completion of any outstanding rendering to images it currently has acquired at the time the swapchain is destroyed. The application can: continue to present any images it acquired and has not yet presented using the old swapchain, as long as it has not entered a state that causes it to return ename:VK_ERROR_OUT_OF_DATE_KHR. However, the application cannot: acquire any more images from the old swapchain regardless of whether or not creation of the new swapchain succeeds. ifdef::VK_KHR_shared_presentable_image[] The application can: continue to use a shared presentable image obtained from pname:oldSwapchain until a presentable image is acquired from the new swapchain, as long as it has not entered a state that causes it to return ename:VK_ERROR_OUT_OF_DATE_KHR. endif::VK_KHR_shared_presentable_image[] .Valid Usage **** * [[VUID-VkSwapchainCreateInfoKHR-surface-01270]] pname:surface must: be a surface that is supported by the device as determined using fname:vkGetPhysicalDeviceSurfaceSupportKHR * [[VUID-VkSwapchainCreateInfoKHR-minImageCount-01271]] pname:minImageCount must: be greater than or equal to the value returned in the pname:minImageCount member of the sname:VkSurfaceCapabilitiesKHR structure returned by fname:vkGetPhysicalDeviceSurfaceCapabilitiesKHR for the surface * [[VUID-VkSwapchainCreateInfoKHR-minImageCount-01272]] pname:minImageCount must: be less than or equal to the value returned in the pname:maxImageCount member of the sname:VkSurfaceCapabilitiesKHR structure returned by fname:vkGetPhysicalDeviceSurfaceCapabilitiesKHR for the surface if the returned pname:maxImageCount is not zero ifdef::VK_KHR_shared_presentable_image[] * [[VUID-VkSwapchainCreateInfoKHR-minImageCount-01383]] pname:minImageCount must: be `1` if pname:presentMode is either ename:VK_PRESENT_MODE_SHARED_DEMAND_REFRESH_KHR or ename:VK_PRESENT_MODE_SHARED_CONTINUOUS_REFRESH_KHR endif::VK_KHR_shared_presentable_image[] * [[VUID-VkSwapchainCreateInfoKHR-imageFormat-01273]] pname:imageFormat and pname:imageColorSpace must: match the pname:format and pname:colorSpace members, respectively, of one of the sname:VkSurfaceFormatKHR structures returned by fname:vkGetPhysicalDeviceSurfaceFormatsKHR for the surface * [[VUID-VkSwapchainCreateInfoKHR-imageExtent-01274]] pname:imageExtent must: be between pname:minImageExtent and pname:maxImageExtent, inclusive, where pname:minImageExtent and pname:maxImageExtent are members of the sname:VkSurfaceCapabilitiesKHR structure returned by fname:vkGetPhysicalDeviceSurfaceCapabilitiesKHR for the surface * [[VUID-VkSwapchainCreateInfoKHR-imageArrayLayers-01275]] pname:imageArrayLayers must: be greater than `0` and less than or equal to the pname:maxImageArrayLayers member of the sname:VkSurfaceCapabilitiesKHR structure returned by fname:vkGetPhysicalDeviceSurfaceCapabilitiesKHR for the surface * [[VUID-VkSwapchainCreateInfoKHR-imageUsage-01276]] pname:imageUsage must: be a subset of the supported usage flags present in the pname:supportedUsageFlags member of the sname:VkSurfaceCapabilitiesKHR structure returned by fname:vkGetPhysicalDeviceSurfaceCapabilitiesKHR for the surface ifdef::VK_KHR_shared_presentable_image[] if pname:presentMode is set to ename:VK_PRESENT_MODE_IMMEDIATE_KHR, ename:VK_PRESENT_MODE_MAILBOX_KHR, ename:VK_PRESENT_MODE_FIFO_KHR or ename:VK_PRESENT_MODE_FIFO_RELAXED_KHR * [[VUID-VkSwapchainCreateInfoKHR-imageUsage-01384]] pname:imageUsage must: be a subset of the supported usage flags present in the pname:sharedPresentSupportedUsageFlags member of the sname:VkSharedPresentSurfaceCapabilitiesKHR structure returned by fname:vkGetPhysicalDeviceSurfaceCapabilities2KHR for the surface if pname:presentMode is set to either ename:VK_PRESENT_MODE_SHARED_DEMAND_REFRESH_KHR or ename:VK_PRESENT_MODE_SHARED_CONTINUOUS_REFRESH_KHR endif::VK_KHR_shared_presentable_image[] * [[VUID-VkSwapchainCreateInfoKHR-imageSharingMode-01277]] If pname:imageSharingMode is ename:VK_SHARING_MODE_CONCURRENT, pname:pQueueFamilyIndices must: be a pointer to an array of pname:queueFamilyIndexCount basetype:uint32_t values * [[VUID-VkSwapchainCreateInfoKHR-imageSharingMode-01278]] If pname:imageSharingMode is ename:VK_SHARING_MODE_CONCURRENT, pname:queueFamilyIndexCount must: be greater than `1` * [[VUID-VkSwapchainCreateInfoKHR-sharingMode-01393]] If pname:sharingMode is ename:VK_SHARING_MODE_CONCURRENT, each element of pname:pQueueFamilyIndices must: be unique and must: be less than pname:pQueueFamilyPropertyCount returned by ifndef::VK_KHR_get_physical_device_properties2[] flink:vkGetPhysicalDeviceQueueFamilyProperties endif::VK_KHR_get_physical_device_properties2[] ifdef::VK_KHR_get_physical_device_properties2[] either flink:vkGetPhysicalDeviceQueueFamilyProperties or flink:vkGetPhysicalDeviceQueueFamilyProperties2KHR endif::VK_KHR_get_physical_device_properties2[] for the pname:physicalDevice that was used to create pname:device * [[VUID-VkSwapchainCreateInfoKHR-preTransform-01279]] pname:preTransform must: be one of the bits present in the pname:supportedTransforms member of the sname:VkSurfaceCapabilitiesKHR structure returned by fname:vkGetPhysicalDeviceSurfaceCapabilitiesKHR for the surface * [[VUID-VkSwapchainCreateInfoKHR-compositeAlpha-01280]] pname:compositeAlpha must: be one of the bits present in the pname:supportedCompositeAlpha member of the sname:VkSurfaceCapabilitiesKHR structure returned by fname:vkGetPhysicalDeviceSurfaceCapabilitiesKHR for the surface * [[VUID-VkSwapchainCreateInfoKHR-presentMode-01281]] pname:presentMode must: be one of the elink:VkPresentModeKHR values returned by fname:vkGetPhysicalDeviceSurfacePresentModesKHR for the surface **** include::../../validity/structs/VkSwapchainCreateInfoKHR.txt[] // refBegin VkSwapchainCreateFlagBitsKHR Bitmask controlling swapchain creation Bits which can: be set in slink:VkSwapchainCreateInfoKHR::pname:flags, specifying parameters of swapchain creation, are: include::../../api/enums/VkSwapchainCreateFlagBitsKHR.txt[] ifdef::VK_KHX_device_group[] * ename:VK_SWAPCHAIN_CREATE_BIND_SFR_BIT_KHX specifies that images created from the swapchain (i.e. with the pname:swapchain member of slink:VkImageSwapchainCreateInfoKHX set to this swapchain's handle) must: use ename:VK_IMAGE_CREATE_BIND_SFR_BIT_KHX. endif::VK_KHX_device_group[] // refEnd VkSwapchainCreateFlagBitsKHR ifdef::VK_KHX_device_group[] // refBegin VkDeviceGroupSwapchainCreateInfoKHX Structure specifying parameters of a newly created swapchain object If the pname:pNext list of slink:VkSwapchainCreateInfoKHR includes a sname:VkDeviceGroupSwapchainCreateInfoKHX structure, then that structure includes a set of device group present modes that the swapchain can: be used with. The sname:VkDeviceGroupSwapchainCreateInfoKHX structure is defined as: include::../../api/structs/VkDeviceGroupSwapchainCreateInfoKHX.txt[] * pname:sType is the type of this structure. * pname:pNext is `NULL` or a pointer to an extension-specific structure. * pname:modes is a bitfield of modes that the swapchain can: be used with. If this structure is not present, pname:modes is considered to be ename:VK_DEVICE_GROUP_PRESENT_MODE_LOCAL_BIT_KHX. include::../../validity/structs/VkDeviceGroupSwapchainCreateInfoKHX.txt[] endif::VK_KHX_device_group[] ifdef::VK_EXT_display_control[] include::../VK_EXT_display_control/swapchain_counters.txt[] endif::VK_EXT_display_control[] As mentioned above, if fname:vkCreateSwapchainKHR succeeds, it will return a handle to a swapchain that contains an array of at least pname:minImageCount presentable images. While acquired by the application, presentable images can: be used in any way that equivalent non-presentable images can: be used. A presentable image is equivalent to a non-presentable image created with the following sname:VkImageCreateInfo parameters: [[swapchain-wsi-image-create-info]] [options="header"] |==== | sname:VkImageCreateInfo Field | Value ifdef::VK_KHX_device_group[] | pname:flags | ename:VK_IMAGE_CREATE_BIND_SFR_BIT_KHX if ename:VK_SWAPCHAIN_CREATE_BIND_SFR_BIT_KHX is set, else 0 endif::VK_KHX_device_group[] ifndef::VK_KHX_device_group[] | pname:flags | 0 endif::VK_KHX_device_group[] | pname:imageType | ename:VK_IMAGE_TYPE_2D | pname:format | `pCreateInfo->imageFormat` | pname:extent | `{pCreateInfo->imageExtent.width, pCreateInfo->imageExtent.height, 1}` | pname:mipLevels | 1 | pname:arrayLayers | `pCreateInfo->imageArrayLayers` | pname:samples | ename:VK_SAMPLE_COUNT_1_BIT | pname:tiling | ename:VK_IMAGE_TILING_OPTIMAL | pname:usage | `pCreateInfo->imageUsage` | pname:sharingMode | `pCreateInfo->imageSharingMode` | pname:queueFamilyIndexCount | `pCreateInfo->queueFamilyIndexCount` | pname:pQueueFamilyIndices | `pCreateInfo->pQueueFamilyIndices` | pname:initialLayout | ename:VK_IMAGE_LAYOUT_UNDEFINED |==== The sname:VkSurfaceKHR associated with a swapchain must: not be destroyed until after the swapchain is destroyed. The native window referred to by pname:surface must: not already be associated with a swapchain other than pname:oldSwapchain, or with a non-Vulkan graphics API surface. Like core functions, several WSI functions, including fname:vkCreateSwapchainKHR return ename:VK_ERROR_DEVICE_LOST if the logical device was lost. See <>. As with most core objects, sname:VkSwapchainKHR is a child of the device and is affected by the lost state; it must: be destroyed before destroying the sname:VkDevice. However, sname:VkSurfaceKHR is not a child of any sname:VkDevice and is not otherwise affected by the lost device. After successfully recreating a sname:VkDevice, the same sname:VkSurfaceKHR can: be used to create a new sname:VkSwapchainKHR, provided the previous one was destroyed. [NOTE] .Note ==== As mentioned in <>, after a lost device event, the sname:VkPhysicalDevice may: also be lost. If other sname:VkPhysicalDevice are available, they can: be used together with the same sname:VkSurfaceKHR to create the new sname:VkSwapchainKHR, however the application must: query the surface capabilities again, because they may: differ on a per-physical device basis. ==== // refBegin vkDestroySwapchainKHR - Destroy a swapchain object To destroy a swapchain object call: include::../../api/protos/vkDestroySwapchainKHR.txt[] * pname:device is the sname:VkDevice associated with pname:swapchain. * pname:swapchain is the swapchain to destroy. * pname:pAllocator is the allocator used for host memory allocated for the swapchain object when there is no more specific allocator available (see <>). pname:swapchain and all associated sname:VkImage handles are destroyed, and must: not be acquired or used any more by the application. The memory of each sname:VkImage will only be freed after that image is no longer used by the platform. For example, if one image of the swapchain is being displayed in a window, the memory for that image may: not be freed until the window is destroyed, or another swapchain is created for the window. Destroying the swapchain does not invalidate the parent sname:VkSurfaceKHR, and a new swapchain can: be created with it. ifdef::VK_KHR_display_swapchain[] include::../VK_KHR_display_swapchain/destroy_swapchain_interactions.txt[] endif::VK_KHR_display_swapchain[] .Valid Usage **** * [[VUID-vkDestroySwapchainKHR-swapchain-01282]] All uses of presentable images acquired from pname:swapchain must: have completed execution * [[VUID-vkDestroySwapchainKHR-swapchain-01283]] If sname:VkAllocationCallbacks were provided when pname:swapchain was created, a compatible set of callbacks must: be provided here * [[VUID-vkDestroySwapchainKHR-swapchain-01284]] If no sname:VkAllocationCallbacks were provided when pname:swapchain was created, pname:pAllocator must: be `NULL` **** include::../../validity/protos/vkDestroySwapchainKHR.txt[] ifdef::VK_KHR_display_swapchain[] include::../VK_KHR_display_swapchain/create_shared_swapchains.txt[] endif::VK_KHR_display_swapchain[] // refBegin vkGetSwapchainImagesKHR - Obtain the array of presentable images associated with a swapchain To obtain the array of presentable images associated with a swapchain, call: include::../../api/protos/vkGetSwapchainImagesKHR.txt[] * pname:device is the device associated with pname:swapchain. * pname:swapchain is the swapchain to query. * pname:pSwapchainImageCount is a pointer to an integer related to the number of presentable images available or queried, as described below. * pname:pSwapchainImages is either `NULL` or a pointer to an array of sname:VkImage handles. If pname:pSwapchainImages is `NULL`, then the number of presentable images for pname:swapchain is returned in pname:pSwapchainImageCount. Otherwise, pname:pSwapchainImageCount must: point to a variable set by the user to the number of elements in the pname:pSwapchainImages array, and on return the variable is overwritten with the number of structures actually written to pname:pSwapchainImages. If the value of pname:pSwapchainImageCount is less than the number of presentable images for pname:swapchain, at most pname:pSwapchainImageCount structures will be written. If pname:pSwapchainImageCount is smaller than the number of presentable images for pname:swapchain, ename:VK_INCOMPLETE will be returned instead of ename:VK_SUCCESS to indicate that not all the available values were returned. include::../../validity/protos/vkGetSwapchainImagesKHR.txt[] [NOTE] .Note ==== By knowing all presentable images used in the swapchain, the application can: create command buffers that reference these images prior to entering its main rendering loop. ==== The implementation will have already allocated and bound the memory backing the sname:VkImages returned by fname:vkGetSwapchainImagesKHR. The memory for each image will not alias with the memory for other images or with any sname:VkDeviceMemory object. As such, performing any operation affecting the binding of memory to a presentable image results in undefined behavior. All presentable images are initially in the ename:VK_IMAGE_LAYOUT_UNDEFINED layout, thus before using presentable images, the application must: transition them to a valid layout for the intended use. Further, the lifetime of presentable images is controlled by the implementation so destroying a presentable image with flink:vkDestroyImage results in undefined behavior. See flink:vkDestroySwapchainKHR for further details on the lifetime of presentable images. ifdef::VK_KHX_device_group[] Images can: also be created by using flink:vkCreateImage with slink:VkImageSwapchainCreateInfoKHX and bound to swapchain memory using flink:vkBindImageMemory2KHX with slink:VkBindImageMemorySwapchainInfoKHX. These images can: be used anywhere swapchain images are used, and are useful in logical devices with multiple physical devices to create peer memory bindings of swapchain memory. These images and bindings have no effect on what memory is presented. Unlike images retrieved from fname:vkGetSwapchainImagesKHR, these images must: be destroyed with flink:vkDestroyImage. endif::VK_KHX_device_group[] // refBegin vkAcquireNextImageKHR - Retrieve the index of the next available presentable image To acquire an available presentable image to use, and retrieve the index of that image, call: include::../../api/protos/vkAcquireNextImageKHR.txt[] * pname:device is the device associated with pname:swapchain. * pname:swapchain is the swapchain from which an image is being acquired. * pname:timeout indicates how long the function waits, in nanoseconds, if no image is available. * pname:semaphore is dlink:VK_NULL_HANDLE or a semaphore to signal. * pname:fence is dlink:VK_NULL_HANDLE or a fence to signal. * pname:pImageIndex is a pointer to a code:uint32_t that is set to the index of the next image to use (i.e. an index into the array of images returned by fname:vkGetSwapchainImagesKHR). .Valid Usage **** * [[VUID-vkAcquireNextImageKHR-swapchain-01285]] pname:swapchain must: not have been replaced by being passed as the sname:VkSwapchainCreateInfoKHR::pname:oldSwapchain value to fname:vkCreateSwapchainKHR * [[VUID-vkAcquireNextImageKHR-semaphore-01286]] If pname:semaphore is not dlink:VK_NULL_HANDLE it must: be unsignaled * [[VUID-vkAcquireNextImageKHR-fence-01287]] If pname:fence is not dlink:VK_NULL_HANDLE it must: be unsignaled and must: not be associated with any other queue command that has not yet completed execution on that queue **** include::../../validity/protos/vkAcquireNextImageKHR.txt[] When successful, fname:vkAcquireNextImageKHR acquires a presentable image that the application can: use, and sets pname:pImageIndex to the index of that image. The presentation engine may: not have finished reading from the image at the time it is acquired, so the application must: use pname:semaphore and/or pname:fence to ensure that the image layout and contents are not modified until the presentation engine reads have completed. As mentioned above, the presentation engine controls the order in which presentable images are made available to the application. This allows the platform to handle special situations. The order in which images are acquired is implementation-dependent. Images may: be acquired in a seemingly random order that is not a simple round-robin. If a swapchain has enough presentable images, applications can: acquire multiple images without an intervening fname:vkQueuePresentKHR. Applications can: present images in a different order than the order in which they were acquired. If pname:timeout is 0, fname:vkAcquireNextImageKHR will not block, but will either succeed or return ename:VK_NOT_READY. If pname:timeout is `UINT64_MAX`, the function will not return until an image is acquired from the presentation engine. Other values for pname:timeout will cause the function to return when an image becomes available, or when the specified number of nanoseconds have passed (in which case it will return ename:VK_TIMEOUT). An error can: also cause fname:vkAcquireNextImageKHR to return early. [NOTE] .Note ==== As mentioned above, the presentation engine may: be asynchronous with respect to the application and/or logical device. fname:vkAcquireNextImageKHR may: return as soon as it can: identify which image will be acquired, and can: guarantee that pname:semaphore and pname:fence will be signaled by the presentation engine; and may: not successfully return sooner. The application uses pname:timeout to specify how long fname:vkAcquireNextImageKHR waits for an image to become acquired. ==== Applications cannot: rely on fname:vkAcquireNextImageKHR blocking in order to meter their rendering speed. Various factors can: interrupt fname:vkAcquireNextImageKHR from blocking. [NOTE] .Note ==== For example, if an error occurs, fname:vkAcquireNextImageKHR may: return even though no image is available. As another example, some presentation engines are able to enqueue an unbounded number of presentation and acquire next image operations such that fname:vkAcquireNextImageKHR never needs to wait for completion of outstanding present operations before returning. ==== The availability of presentable images is influenced by factors such as the implementation of the presentation engine, the elink:VkPresentModeKHR being used, the number of images in the swapchain, the number of images that the application has acquired at any given time, and the performance of the application. The value of sname:VkSurfaceCapabilitiesKHR::pname:minImageCount indicates how many images must: be in the swapchain in order for fname:vkAcquireNextImageKHR to acquire an image if the application currently has no acquired images. Let _n_ be the total number of images in the swapchain, _m_ be the value of sname:VkSurfaceCapabilitiesKHR::pname:minImageCount, and _a_ be the number of presentable images that the application has currently acquired (i.e. images acquired with fname:vkAcquireNextImageKHR, but not yet presented with fname:vkQueuePresentKHR). fname:vkAcquireNextImageKHR can: always succeed if [eq]#a {leq} n - m# at the time fname:vkAcquireNextImageKHR is called. fname:vkAcquireNextImageKHR should: not be called if [eq]#a > n - m# with a pname:timeout of code:UINT64_MAX; in such a case, fname:vkAcquireNextImageKHR may: block indefinitely. [NOTE] .Note ==== For example, if the pname:minImageCount member of sname:VkSurfaceCapabilitiesKHR is 2, and the application creates a swapchain with 2 presentable images, the application can: acquire one image, and must: present it before trying to acquire another image. If we modify this example so that the application wishes to acquire up to 3 presentable images simultaneously, it must: request a minimum image count of 4 when creating the swapchain. ==== If pname:semaphore is not dlink:VK_NULL_HANDLE, the semaphore must: be unsignaled and not have any uncompleted signal or wait operations pending. It will become signaled when the application can: use the image. Queue operations that access the image contents must: wait until the semaphore signals; typically applications should: include the semaphore in the pname:pWaitSemaphores list for the queue submission that transitions the image away from the ename:VK_IMAGE_LAYOUT_PRESENT_SRC_KHR layout. Use of the semaphore allows rendering operations to be recorded and submitted before the presentation engine has completed its use of the image. If pname:fence is not equal to dlink:VK_NULL_HANDLE, the fence must: be unsignaled and not have any uncompleted signal operations pending. It will become signaled when the application can: use the image. Applications can: use this to meter their frame generation work to match the presentation rate. pname:semaphore and pname:fence must: not both be equal to dlink:VK_NULL_HANDLE. An application must: wait until either the pname:semaphore or pname:fence is signaled before using the presentable image. pname:semaphore and pname:fence may: already be signaled when fname:vkAcquireNextImageKHR returns, if the image is being acquired for the first time, or if the presentable image is immediately ready for use. A successful call to fname:vkAcquireNextImageKHR counts as a signal operation on pname:semaphore for the purposes of queue forward-progress requirements. The semaphore is guaranteed to signal, so a wait operation can: be queued for the semaphore without risk of deadlock. The fname:vkCmdWaitEvents or fname:vkCmdPipelineBarrier used to transition the image away from ename:VK_IMAGE_LAYOUT_PRESENT_SRC_KHR layout must: have pname:dstStageMask and pname:dstAccessMask parameters set based on the next use of the image. The application must: use <> and <> to prevent the image transition from occurring before the semaphore passed to fname:vkAcquireNextImageKHR has signaled. [NOTE] .Note ==== When the presentable image will be written by some stage [eq]#S#, the recommended idiom for ensuring the semaphore signals before the transition occurs is: * The batch that contains the transition includes the image-acquire semaphore in the list of semaphores to wait for, with a wait stage mask that includes [eq]#S#. * The pipeline barrier that performs the transition includes [eq]#S# in both the pname:srcStageMask and pname:dstStageMask. This causes the pipeline barrier to wait at [eq]#S# until the semaphore signals before performing the transition and memory barrier, while allowing earlier pipeline stages of subsequent commands to proceed. ==== After a successful return, the image indicated by pname:pImageIndex will still be in the ename:VK_IMAGE_LAYOUT_PRESENT_SRC_KHR layout if it was previously presented, or in the ename:VK_IMAGE_LAYOUT_UNDEFINED layout if this is the first time it has been acquired. [NOTE] .Note ==== Exclusive ownership of presentable images corresponding to a swapchain created with ename:VK_SHARING_MODE_EXCLUSIVE as defined in <> is not altered by a call to fname:vkAcquireNextImageKHR. That means upon the first acquisition from such a swapchain presentable images are not owned by any queue family, while at subsequent acquisitions the presentable images remain owned by the queue family the image was previously presented on. ==== The possible return values for fname:vkAcquireNextImageKHR() depend on the pname:timeout provided: * ename:VK_SUCCESS is returned if an image became available. * ename:VK_ERROR_SURFACE_LOST_KHR if the surface becomes no longer available. * ename:VK_NOT_READY is returned if pname:timeout is zero and no image was available. * ename:VK_TIMEOUT is returned if pname:timeout is greater than zero and less than `UINT64_MAX`, and no image became available within the time allowed. * ename:VK_SUBOPTIMAL_KHR is returned if an image became available, and the swapchain no longer matches the surface properties exactly, but can: still be used to present to the surface successfully. [NOTE] .Note ==== This may: happen, for example, if the platform surface has been resized but the platform is able to scale the presented images to the new size to produce valid surface updates. It is up to applications to decide whether they prefer to continue using the current swapchain indefinitely or temporarily in this state, or to re-create the swapchain to better match the platform surface properties. ==== * ename:VK_ERROR_OUT_OF_DATE_KHR is returned if the surface has changed in such a way that it is no longer compatible with the swapchain, and further presentation requests using the swapchain will fail. Applications must: query the new surface properties and recreate their swapchain if they wish to continue presenting to the surface. If the native surface and presented image sizes no longer match, presentation may: fail. If presentation does succeed, parts of the native surface may: be undefined, parts of the presented image may: have been clipped before presentation, and/or the image may: have been scaled (uniformly or not uniformly) before presentation. It is the application's responsibility to detect surface size changes and react appropriately. If presentation fails because of a mismatch in the surface and presented image sizes, a ename:VK_ERROR_OUT_OF_DATE_KHR error will be returned. Before an application can: present an image, the image's layout must: be transitioned to the ename:VK_IMAGE_LAYOUT_PRESENT_SRC_KHR ifdef::VK_KHR_shared_presentable_image[] layout, or for a shared presentable image the ename:VK_IMAGE_LAYOUT_SHARED_PRESENT_KHR endif::VK_KHR_shared_presentable_image[] layout. .Note [NOTE] ==== When transitioning the image to ifdef::VK_KHR_shared_presentable_image[] ename:VK_IMAGE_LAYOUT_SHARED_PRESENT_KHR or endif::VK_KHR_shared_presentable_image[] ename:VK_IMAGE_LAYOUT_PRESENT_SRC_KHR, there is no need to delay subsequent processing, or perform any visibility operations (as flink:vkQueuePresentKHR performs automatic visibility operations). To achieve this, the pname:dstAccessMask member of the slink:VkImageMemoryBarrier should: be set to `0`, and the pname:dstStageMask parameter should: be set to ename:VK_PIPELINE_STAGE_BOTTOM_OF_PIPE_BIT. ==== ifdef::VK_KHX_device_group[] // refBegin vkAcquireNextImage2KHX Retrieve the index of the next available presentable image To acquire an available presentable image to use, and retrieve the index of that image, call: include::../../api/protos/vkAcquireNextImage2KHX.txt[] * pname:device is the device associated with pname:swapchain. * pname:pAcquireInfo is a pointer to a structure of type slink:VkAcquireNextImageInfoKHX containing parameters of the acquire. * pname:pImageIndex is a pointer to a code:uint32_t that is set to the index of the next image to use. include::../../validity/protos/vkAcquireNextImage2KHX.txt[] // refBegin VkAcquireNextImageInfoKHX Structure specifying parameters of the acquire The sname:VkAcquireNextImageInfoKHX structure is defined as: include::../../api/structs/VkAcquireNextImageInfoKHX.txt[] * pname:sType is the type of this structure. * pname:pNext is `NULL` or a pointer to an extension-specific structure. * pname:swapchain is the swapchain from which an image is being acquired. * pname:timeout indicates how long the function waits, in nanoseconds, if no image is available. * pname:semaphore is code:VK_NULL_HANDLE or a semaphore to signal. * pname:fence is code:VK_NULL_HANDLE or a fence to signal. * pname:deviceMask is a mask of physical devices for which the swapchain image will be ready to use when the semaphore or fence is signaled. If flink:vkAcquireNextImageKHR is used, the device mask is considered to include all physical devices in the logical device. [NOTE] .Note ==== flink:vkAcquireNextImage2KHX signals at most one semaphore, even if the application requests waiting for multiple physical devices to be ready via the pname:deviceMask. However, only a single physical device can: wait on that semaphore, since the semaphore becomes unsignaled when the wait succeeds. For other physical devices to wait for the image to be ready, it is necessary for the application to submit semaphore signal operation(s) to that first physical device to signal additional semaphore(s) after the wait succeeds, which the other physical device(s) can: wait upon. ==== .Valid Usage **** * [[VUID-VkAcquireNextImageInfoKHX-semaphore-01288]] If pname:semaphore is not dlink:VK_NULL_HANDLE it must: be unsignaled * [[VUID-VkAcquireNextImageInfoKHX-fence-01289]] If pname:fence is not dlink:VK_NULL_HANDLE it must: be unsignaled and must: not be associated with any other queue command that has not yet completed execution on that queue * [[VUID-VkAcquireNextImageInfoKHX-deviceMask-01290]] pname:deviceMask must: be a valid device mask * [[VUID-VkAcquireNextImageInfoKHX-deviceMask-01291]] pname:deviceMask must: not be zero **** include::../../validity/structs/VkAcquireNextImageInfoKHX.txt[] endif::VK_KHX_device_group[] // refBegin vkQueuePresentKHR - Queue an image for presentation After queueing all rendering commands and transitioning the image to the correct layout, to queue an image for presentation, call: include::../../api/protos/vkQueuePresentKHR.txt[] * pname:queue is a queue that is capable of presentation to the target surface's platform on the same device as the image's swapchain. * pname:pPresentInfo is a pointer to an instance of the slink:VkPresentInfoKHR structure specifying the parameters of the presentation. .Valid Usage **** * [[VUID-vkQueuePresentKHR-pSwapchains-01292]] Any given element of pname:pSwapchains member of pname:pPresentInfo must: be a swapchain that is created for a surface for which presentation is supported from pname:queue as determined using a call to fname:vkGetPhysicalDeviceSurfaceSupportKHR ifdef::VK_KHR_display_swapchain[] * [[VUID-vkQueuePresentKHR-pSwapchains-01293]] If more than one member of pname:pSwapchains was created from a display surface, all display surfaces referenced that refer to the same display must: use the same display mode endif::VK_KHR_display_swapchain[] * [[VUID-vkQueuePresentKHR-pWaitSemaphores-01294]] When a semaphore unsignal operation defined by the elements of the pname:pWaitSemaphores member of pname:pPresentInfo executes on pname:queue, no other queue must: be waiting on the same semaphore. * [[VUID-vkQueuePresentKHR-pWaitSemaphores-01295]] All elements of the pname:pWaitSemaphores member of pname:pPresentInfo must: be semaphores that are signaled, or have <> previously submitted for execution. **** Any writes to memory backing the images referenced by the pname:pImageIndices and pname:pSwapchains members of pname:pPresentInfo, that are available before flink:vkQueuePresentKHR is executed, are automatically made visible to the read access performed by the presentation engine. This automatic visibility operation for an image happens-after the semaphore signal operation, and happens-before the presentation engine accesses the image. include::../../validity/protos/vkQueuePresentKHR.txt[] // refBegin VkPresentInfoKHR - Structure describing parameters of a queue presentation The sname:VkPresentInfoKHR structure is defined as: include::../../api/structs/VkPresentInfoKHR.txt[] * pname:sType is the type of this structure. * pname:pNext is `NULL` or a pointer to an extension-specific structure. * pname:waitSemaphoreCount is the number of semaphores to wait for before issuing the present request. The number may: be zero. * pname:pWaitSemaphores, if not `NULL`, is an array of sname:VkSemaphore objects with pname:waitSemaphoreCount entries, and specifies the semaphores to wait for before issuing the present request. * pname:swapchainCount is the number of swapchains being presented to by this command. * pname:pSwapchains is an array of sname:VkSwapchainKHR objects with pname:swapchainCount entries. A given swapchain must: not appear in this list more than once. * pname:pImageIndices is an array of indices into the array of each swapchain's presentable images, with pname:swapchainCount entries. Each entry in this array identifies the image to present on the corresponding entry in the pname:pSwapchains array. * pname:pResults is an array of elink:VkResult typed elements with pname:swapchainCount entries. Applications that do not need per-swapchain results can: use `NULL` for pname:pResults. If non-`NULL`, each entry in pname:pResults will be set to the elink:VkResult for presenting the swapchain corresponding to the same index in pname:pSwapchains. .Valid Usage **** * [[VUID-VkPresentInfoKHR-pImageIndices-01296]] Any given element of pname:pImageIndices must: be the index of a presentable image acquired from the swapchain specified by the corresponding element of the pname:pSwapchains array, and the presented image subresource must: be in the ename:VK_IMAGE_LAYOUT_PRESENT_SRC_KHR ifdef::VK_KHR_shared_presentable_image[] or ename:VK_IMAGE_LAYOUT_SHARED_PRESENT_KHR endif::VK_KHR_shared_presentable_image[] layout at the time the operation is executed on a sname:VkDevice **** include::../../validity/structs/VkPresentInfoKHR.txt[] ifdef::VK_KHR_incremental_present[] include::../VK_KHR_incremental_present/wsi.txt[] endif::VK_KHR_incremental_present[] ifdef::VK_KHR_display_swapchain[] include::../VK_KHR_display_swapchain/display_swapchain_present.txt[] endif::VK_KHR_display_swapchain[] ifdef::VK_KHX_device_group[] // refBegin VkDeviceGroupPresentInfoKHX Mode and mask controlling which physical devices' images are presented If the pname:pNext list of slink:VkPresentInfoKHR includes a sname:VkDeviceGroupPresentInfoKHX structure, then that structure includes an array of device masks and a device group present mode. The sname:VkDeviceGroupPresentInfoKHX structure is defined as: include::../../api/structs/VkDeviceGroupPresentInfoKHX.txt[] * pname:sType is the type of this structure. * pname:pNext is `NULL` or a pointer to an extension-specific structure. * pname:swapchainCount is zero or the number of elements in pname:pDeviceMasks. * pname:pDeviceMasks is an array of device masks, one for each element of slink:VkPresentInfoKHR::pSwapchains. * pname:mode is the device group present mode that will be used for this present. If pname:mode is ename:VK_DEVICE_GROUP_PRESENT_MODE_LOCAL_BIT_KHX, then each element of pname:pDeviceMasks selects which instance of the swapchain image is presented. Each element of pname:pDeviceMasks must: have exactly one bit set, and the corresponding physical device must: have a presentation engine as reported by slink:VkDeviceGroupPresentCapabilitiesKHX. If pname:mode is ename:VK_DEVICE_GROUP_PRESENT_MODE_REMOTE_BIT_KHX, then each element of pname:pDeviceMasks selects which instance of the swapchain image is presented. Each element of pname:pDeviceMasks must: have exactly one bit set, and some physical device in the logical device must: include that bit in its slink:VkDeviceGroupPresentCapabilitiesKHX::pname:presentMask. If pname:mode is ename:VK_DEVICE_GROUP_PRESENT_MODE_SUM_BIT_KHX, then each element of pname:pDeviceMasks selects which instances of the swapchain image are component-wise summed and the sum of those images is presented. If the sum in any component is outside the representable range, the value of that component is undefined. Each element of pname:pDeviceMasks must: have a value for which all set bits are set in one of the elements of slink:VkDeviceGroupPresentCapabilitiesKHX::pname:presentMask. If pname:mode is ename:VK_DEVICE_GROUP_PRESENT_MODE_LOCAL_MULTI_DEVICE_BIT_KHX, then each element of pname:pDeviceMasks selects which instance(s) of the swapchain images are presented. For each bit set in each element of pname:pDeviceMasks, the corresponding physical device must: have a presentation engine as reported by slink:VkDeviceGroupPresentCapabilitiesKHX. If sname:VkDeviceGroupPresentInfoKHX is not provided or pname:swapchainCount is zero then the masks are considered to be `1`. If sname:VkDeviceGroupPresentInfoKHX is not provided, pname:mode is considered to be ename:VK_DEVICE_GROUP_PRESENT_MODE_LOCAL_BIT_KHX. .Valid Usage **** * [[VUID-VkDeviceGroupPresentInfoKHX-swapchainCount-01297]] pname:swapchainCount must: equal `0` or slink:VkPresentInfoKHR::pname:swapchainCount * [[VUID-VkDeviceGroupPresentInfoKHX-mode-01298]] If pname:mode is ename:VK_DEVICE_GROUP_PRESENT_MODE_LOCAL_BIT_KHX, then each element of pname:pDeviceMasks must: have exactly one bit set, and the corresponding element of slink:VkDeviceGroupPresentCapabilitiesKHX::pname:presentMask must: be non-zero * [[VUID-VkDeviceGroupPresentInfoKHX-mode-01299]] If pname:mode is ename:VK_DEVICE_GROUP_PRESENT_MODE_REMOTE_BIT_KHX, then each element of pname:pDeviceMasks must: have exactly one bit set, and some physical device in the logical device must: include that bit in its slink:VkDeviceGroupPresentCapabilitiesKHX::pname:presentMask. * [[VUID-VkDeviceGroupPresentInfoKHX-mode-01300]] If pname:mode is ename:VK_DEVICE_GROUP_PRESENT_MODE_SUM_BIT_KHX, then each element of pname:pDeviceMasks must: have a value for which all set bits are set in one of the elements of slink:VkDeviceGroupPresentCapabilitiesKHX::pname:presentMask * [[VUID-VkDeviceGroupPresentInfoKHX-mode-01301]] If pname:mode is ename:VK_DEVICE_GROUP_PRESENT_MODE_LOCAL_MULTI_DEVICE_BIT_KHX, then for each bit set in each element of pname:pDeviceMasks, the corresponding element of slink:VkDeviceGroupPresentCapabilitiesKHX::pname:presentMask must: be non-zero * [[VUID-VkDeviceGroupPresentInfoKHX-pDeviceMasks-01302]] The value of each element of pname:pDeviceMasks must: be equal to the device mask passed in slink:VkAcquireNextImageInfoKHX::pname:deviceMask when the image index was last acquired * [[VUID-VkDeviceGroupPresentInfoKHX-mode-01303]] pname:mode must: have exactly one bit set, and that bit must: have been included in slink:VkDeviceGroupSwapchainCreateInfoKHX::pname:modes **** include::../../validity/structs/VkDeviceGroupPresentInfoKHX.txt[] endif::VK_KHX_device_group[] ifdef::VK_GOOGLE_display_timing[] include::../VK_GOOGLE_display_timing/PresentTimeInfo.txt[] endif::VK_GOOGLE_display_timing[] fname:vkQueuePresentKHR, releases the acquisition of the images referenced by pname:imageIndices. The queue family corresponding to the queue fname:vkQueuePresentKHR is executed on must: have ownership of the presented images as defined in <>. fname:vkQueuePresentKHR does not alter the queue family ownership, but the presented images must: not be used again before they have been reacquired using fname:vkAcquireNextImageKHR. The processing of the presentation happens in issue order with other queue operations, but semaphores have to be used to ensure that prior rendering and other commands in the specified queue complete before the presentation begins. The presentation command itself does not delay processing of subsequent commands on the queue, however, presentation requests sent to a particular queue are always performed in order. Exact presentation timing is controlled by the semantics of the presentation engine and native platform in use. ifdef::VK_KHR_display_swapchain[] include::../VK_KHR_display_swapchain/queue_present_interactions.txt[] endif::VK_KHR_display_swapchain[] The result codes ename:VK_ERROR_OUT_OF_DATE_KHR and ename:VK_SUBOPTIMAL_KHR have the same meaning when returned by fname:vkQueuePresentKHR as they do when returned by fname:vkAcquireNextImageKHR(). If multiple swapchains are presented, the result code is determined applying the following rules in order: * If the device is lost, ename:VK_ERROR_DEVICE_LOST is returned. * If any of the target surfaces are no longer available the error ename:VK_ERROR_SURFACE_LOST_KHR is returned. * If any of the presents would have a result of ename:VK_ERROR_OUT_OF_DATE_KHR if issued separately then ename:VK_ERROR_OUT_OF_DATE_KHR is returned. * If any of the presents would have a result of ename:VK_SUBOPTIMAL_KHR if issued separately then ename:VK_SUBOPTIMAL_KHR is returned. * Otherwise ename:VK_SUCCESS is returned. Presentation is a read-only operation that will not affect the content of the presentable images. Upon reacquiring the image and transitioning it away from the ename:VK_IMAGE_LAYOUT_PRESENT_SRC_KHR layout, the contents will be the same as they were prior to transitioning the image to the present source layout and presenting it. However, if a mechanism other than Vulkan is used to modify the platform window associated with the swapchain, the content of all presentable images in the swapchain becomes undefined. ifdef::VK_EXT_hdr_metadata[] include::../VK_EXT_hdr_metadata.txt[] endif::VK_EXT_hdr_metadata[]