143 lines
4.8 KiB
Plaintext
143 lines
4.8 KiB
Plaintext
// Copyright (c) 2014-2018 Khronos Group. This work is licensed under a
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// Creative Commons Attribution 4.0 International License; see
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// http://creativecommons.org/licenses/by/4.0/
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include::meta/VK_KHR_win32_surface.txt[]
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*Last Modified Date*::
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2017-04-24
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*IP Status*::
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No known IP claims.
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*Contributors*::
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- Patrick Doane, Blizzard
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- Jason Ekstrand, Intel
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- Ian Elliott, LunarG
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- Courtney Goeltzenleuchter, LunarG
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- Jesse Hall, Google
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- James Jones, NVIDIA
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- Antoine Labour, Google
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- Jon Leech, Khronos
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- David Mao, AMD
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- Norbert Nopper, Freescale
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- Alon Or-bach, Samsung
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- Daniel Rakos, AMD
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- Graham Sellers, AMD
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- Ray Smith, ARM
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- Jeff Vigil, Qualcomm
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- Chia-I Wu, LunarG
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The `VK_KHR_win32_surface` extension is an instance extension.
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It provides a mechanism to create a slink:VkSurfaceKHR object (defined by
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the `<<VK_KHR_surface>>` extension) that refers to a Win32 code:HWND, as
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well as a query to determine support for rendering to the windows desktop.
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=== New Object Types
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None
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=== New Enum Constants
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* Extending elink:VkStructureType:
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** ename:VK_STRUCTURE_TYPE_WIN32_SURFACE_CREATE_INFO_KHR
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=== New Enums
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None
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=== New Structures
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* slink:VkWin32SurfaceCreateInfoKHR
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=== New Functions
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* flink:vkCreateWin32SurfaceKHR
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* flink:vkGetPhysicalDeviceWin32PresentationSupportKHR
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=== Issues
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1) Does Win32 need a way to query for compatibility between a particular
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physical device and a specific screen? Compatibility between a physical
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device and a window generally only depends on what screen the window is on.
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However, there is not an obvious way to identify a screen without already
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having a window on the screen.
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*RESOLVED*: No.
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While it may be useful, there is not a clear way to do this on Win32.
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However, a method was added to query support for presenting to the windows
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desktop as a whole.
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2) If a native window object (code:HWND) is used by one graphics API, and
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then is later used by a different graphics API (one of which is Vulkan), can
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these uses interfere with each other?
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*RESOLVED*: Yes.
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Uses of a window object by multiple graphics APIs results in undefined
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behavior.
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Such behavior may succeed when using one Vulkan implementation but fail when
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using a different Vulkan implementation.
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Potential failures include:
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* Creating then destroying a flip presentation model DXGI swapchain on a
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window object can prevent flink:vkCreateSwapchainKHR from succeeding on
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the same window object.
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* Creating then destroying a slink:VkSwapchainKHR on a window object can
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prevent creation of a bitblt model DXGI swapchain on the same window
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object.
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* Creating then destroying a slink:VkSwapchainKHR on a window object can
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effectively code:SetPixelFormat to a different format than the format
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chosen by an OpenGL application.
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* Creating then destroying a slink:VkSwapchainKHR on a window object on one
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slink:VkPhysicalDevice can prevent flink:vkCreateSwapchainKHR from
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succeeding on the same window object, but on a different
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slink:VkPhysicalDevice that is associated with a different Vulkan ICD.
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In all cases the problem can be worked around by creating a new window
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object.
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Technical details include:
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* Creating a DXGI swapchain over a window object can alter the object for
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the remainder of its lifetime.
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The alteration persists even after the DXGI swapchain has been destroyed.
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This alteration can make it impossible for a conformant Vulkan
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implementation to create a slink:VkSwapchainKHR over the same window
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object.
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Mention of this alteration can be found in the remarks section of the
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MSDN documentation for code:DXGI_SWAP_EFFECT.
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* Calling GDI's code:SetPixelFormat (needed by OpenGL's WGL layer) on a
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window object alters the object for the remainder of its lifetime.
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The MSDN documentation for code:SetPixelFormat explains that a window
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object's pixel format can be set only one time.
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* Creating a slink:VkSwapchainKHR over a window object can alter the object
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for the remaining life of its lifetime.
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Either of the above alterations may occur as a side-effect of
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slink:VkSwapchainKHR.
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=== Version History
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* Revision 1, 2015-09-23 (Jesse Hall)
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- Initial draft, based on the previous contents of VK_EXT_KHR_swapchain
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(later renamed VK_EXT_KHR_surface).
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* Revision 2, 2015-10-02 (James Jones)
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- Added presentation support query for win32 desktops.
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* Revision 3, 2015-10-26 (Ian Elliott)
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- Renamed from VK_EXT_KHR_win32_surface to VK_KHR_win32_surface.
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* Revision 4, 2015-11-03 (Daniel Rakos)
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- Added allocation callbacks to vkCreateWin32SurfaceKHR.
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* Revision 5, 2015-11-28 (Daniel Rakos)
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- Updated the surface create function to take a pCreateInfo structure.
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* Revision 6, 2017-04-24 (Jeff Juliano)
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- Add issue 2 addressing reuse of a native window object in a different
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Graphics API, or by a different Vulkan ICD.
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