1// Copyright 2014-2022 The Khronos Group Inc. 2// 3// SPDX-License-Identifier: CC-BY-4.0 4 5include::{generated}/meta/{refprefix}VK_KHR_display_swapchain.adoc[] 6 7=== Other Extension Metadata 8 9*Last Modified Date*:: 10 2017-03-13 11*IP Status*:: 12 No known IP claims. 13*Contributors*:: 14 - James Jones, NVIDIA 15 - Jeff Vigil, Qualcomm 16 - Jesse Hall, Google 17 18=== Description 19 20This extension provides an API to create a swapchain directly on a device's 21display without any underlying window system. 22 23include::{generated}/interfaces/VK_KHR_display_swapchain.adoc[] 24 25=== Issues 26 271) Should swapchains sharing images each hold a reference to the images, or 28should it be up to the application to destroy the swapchains and images in 29an order that avoids the need for reference counting? 30 31*RESOLVED*: Take a reference. 32The lifetime of presentable images is already complex enough. 33 342) Should the pname:srcRect and pname:dstRect parameters be specified as 35part of the presentation command, or at swapchain creation time? 36 37*RESOLVED*: As part of the presentation command. 38This allows moving and scaling the image on the screen without the need to 39respecify the mode or create a new swapchain and presentable images. 40 413) Should pname:srcRect and pname:dstRect be specified as rects, or separate 42offset/extent values? 43 44*RESOLVED*: As rects. 45Specifying them separately might make it easier for hardware to expose 46support for one but not the other, but in such cases applications must just 47take care to obey the reported capabilities and not use non-zero offsets or 48extents that require scaling, as appropriate. 49 504) How can applications create multiple swapchains that use the same images? 51 52*RESOLVED*: By calling flink:vkCreateSharedSwapchainsKHR. 53 54An earlier resolution used flink:vkCreateSwapchainKHR, chaining multiple 55slink:VkSwapchainCreateInfoKHR structures through pname:pNext. 56In order to allow each swapchain to also allow other extension structs, a 57level of indirection was used: slink:VkSwapchainCreateInfoKHR::pname:pNext 58pointed to a different structure, which had both pname:sType and pname:pNext 59members for additional extensions, and also had a pointer to the next 60slink:VkSwapchainCreateInfoKHR structure. 61The number of swapchains to be created could only be found by walking this 62linked list of alternating structures, and the pname:pSwapchains out 63parameter was reinterpreted to be an array of slink:VkSwapchainKHR handles. 64 65Another option considered was a method to specify a "`shared`" swapchain 66when creating a new swapchain, such that groups of swapchains using the same 67images could be built up one at a time. 68This was deemed unusable because drivers need to know all of the displays an 69image will be used on when determining which internal formats and layouts to 70use for that image. 71 72=== Examples 73 74[NOTE] 75.Note 76==== 77The example code for the `apiext:VK_KHR_display` and 78`VK_KHR_display_swapchain` extensions was removed from the appendix after 79revision 1.0.43. 80The display swapchain creation example code was ported to the cube demo that 81is shipped with the official Khronos SDK, and is being kept up-to-date in 82that location (see: 83https://github.com/KhronosGroup/Vulkan-Tools/blob/master/cube/cube.c). 84==== 85 86=== Version History 87 88 * Revision 1, 2015-07-29 (James Jones) 89 ** Initial draft 90 91 * Revision 2, 2015-08-21 (Ian Elliott) 92 ** Renamed this extension and all of its enumerations, types, functions, 93 etc. 94 This makes it compliant with the proposed standard for Vulkan 95 extensions. 96 ** Switched from "`revision`" to "`version`", including use of the 97 VK_MAKE_VERSION macro in the header file. 98 99 * Revision 3, 2015-09-01 (James Jones) 100 ** Restore single-field revision number. 101 102 * Revision 4, 2015-09-08 (James Jones) 103 ** Allow creating multiple swap chains that share the same images using a 104 single call to vkCreateSwapchainKHR(). 105 106 * Revision 5, 2015-09-10 (Alon Or-bach) 107 ** Removed underscores from SWAP_CHAIN in two enums. 108 109 * Revision 6, 2015-10-02 (James Jones) 110 ** Added support for smart panels/buffered displays. 111 112 * Revision 7, 2015-10-26 (Ian Elliott) 113 ** Renamed from VK_EXT_KHR_display_swapchain to VK_KHR_display_swapchain. 114 115 * Revision 8, 2015-11-03 (Daniel Rakos) 116 ** Updated sample code based on the changes to VK_KHR_swapchain. 117 118 * Revision 9, 2015-11-10 (Jesse Hall) 119 ** Replaced VkDisplaySwapchainCreateInfoKHR with 120 vkCreateSharedSwapchainsKHR, changing resolution of issue #4. 121 122 * Revision 10, 2017-03-13 (James Jones) 123 ** Closed all remaining issues. 124 The specification and implementations have been shipping with the 125 proposed resolutions for some time now. 126 ** Removed the sample code and noted it has been integrated into the 127 official Vulkan SDK cube demo. 128