1// Copyright 2018-2021 The Khronos Group, Inc. 2// 3// SPDX-License-Identifier: CC-BY-4.0 4 5include::{generated}/meta/{refprefix}VK_EXT_full_screen_exclusive.txt[] 6 7=== Other Extension Metadata 8 9*Last Modified Date*:: 10 2019-03-12 11*IP Status*:: 12 No known IP claims. 13*Interactions and External Dependencies*:: 14 - Interacts with Vulkan 1.1 15 - Interacts with `apiext:VK_KHR_device_group` 16 - Interacts with `apiext:VK_KHR_win32_surface` 17*Contributors*:: 18 - Hans-Kristian Arntzen, ARM 19 - Slawomir Grajewski, Intel 20 - Tobias Hector, AMD 21 - James Jones, NVIDIA 22 - Daniel Rakos, AMD 23 - Jeff Juliano, NVIDIA 24 - Joshua Schnarr, NVIDIA 25 - Aaron Hagan, AMD 26 27=== Description 28 29This extension allows applications to set the policy for swapchain creation 30and presentation mechanisms relating to full-screen access. 31Implementations may be able to acquire exclusive access to a particular 32display for an application window that covers the whole screen. 33This can increase performance on some systems by bypassing composition, 34however it can also result in disruptive or expensive transitions in the 35underlying windowing system when a change occurs. 36 37Applications can choose between explicitly disallowing or allowing this 38behavior, letting the implementation decide, or managing this mode of 39operation directly using the new flink:vkAcquireFullScreenExclusiveModeEXT 40and flink:vkReleaseFullScreenExclusiveModeEXT commands. 41 42include::{generated}/interfaces/VK_EXT_full_screen_exclusive.txt[] 43 44=== Issues 45 461) What should the extension & flag be called? 47 48*RESOLVED*: VK_EXT_full_screen_exclusive. 49 50Other options considered (prior to the app-controlled mode) were: 51 52 * VK_EXT_smooth_fullscreen_transition 53 * VK_EXT_fullscreen_behavior 54 * VK_EXT_fullscreen_preference 55 * VK_EXT_fullscreen_hint 56 * VK_EXT_fast_fullscreen_transition 57 * VK_EXT_avoid_fullscreen_exclusive 58 592) Do we need more than a boolean toggle? 60 61*RESOLVED*: Yes. 62 63Using an enum with default/allowed/disallowed/app-controlled enables 64applications to accept driver default behavior, specifically override it in 65either direction without implying the driver is ever required to use 66full-screen exclusive mechanisms, or manage this mode explicitly. 67 683) Should this be a KHR or EXT extension? 69 70*RESOLVED*: EXT, in order to allow it to be shipped faster. 71 724) Can the fullscreen hint affect the surface capabilities, and if so, 73should the hint also be specified as input when querying the surface 74capabilities? 75 76*RESOLVED*: Yes on both accounts. 77 78While the hint does not guarantee a particular fullscreen mode will be used 79when the swapchain is created, it can sometimes imply particular modes will 80NOT be used. 81If the driver determines that it will opt-out of using a particular mode 82based on the policy, and knows it can only support certain capabilities if 83that mode is used, it would be confusing at best to the application to 84report those capabilities in such cases. 85Not allowing implementations to report this state to applications could 86result in situations where applications are unable to determine why 87swapchain creation fails when they specify certain hint values, which could 88result in never- terminating surface creation loops. 89 905) Should full-screen be one word or two? 91 92*RESOLVED*: Two words. 93 94"Fullscreen" is not in my dictionary, and web searches did not turn up 95definitive proof that it is a colloquially accepted compound word. 96Documentation for the corresponding Windows API mechanisms dithers. 97The text consistently uses a hyphen, but none-the-less, there is a 98SetFullscreenState method in the DXGI swapchain object. 99Given this inconclusive external guidance, it is best to adhere to the 100Vulkan style guidelines and avoid inventing new compound words. 101 102=== Version History 103 104 * Revision 4, 2019-03-12 (Tobias Hector) 105 - Added application-controlled mode, and related functions 106 - Tidied up appendix 107 108 * Revision 3, 2019-01-03 (James Jones) 109 - Renamed to VK_EXT_full_screen_exclusive 110 - Made related adjustments to the tri-state enumerant names. 111 112 * Revision 2, 2018-11-27 (James Jones) 113 - Renamed to VK_KHR_fullscreen_behavior 114 - Switched from boolean flag to tri-state enum 115 116 * Revision 1, 2018-11-06 (James Jones) 117 - Internal revision 118