VK_KHR_win32_surface
Other Extension Metadata
Last Modified Date
2017-04-24
IP Status
No known IP claims.
Contributors
- Patrick Doane, Blizzard
- Faith Ekstrand, Intel
- Ian Elliott, LunarG
- Courtney Goeltzenleuchter, LunarG
- Jesse Hall, Google
- James Jones, NVIDIA
- Antoine Labour, Google
- Jon Leech, Khronos
- David Mao, AMD
- Norbert Nopper, Freescale
- Alon Or-bach, Samsung
- Daniel Rakos, AMD
- Graham Sellers, AMD
- Ray Smith, ARM
- Jeff Vigil, Qualcomm
- Chia-I Wu, LunarG
Description
The VK_KHR_win32_surface
extension is an instance extension.
It provides a mechanism to create a VkSurfaceKHR object (defined by
the VK_KHR_surface extension) that refers to a Win32 HWND
, as
well as a query to determine support for rendering to the windows desktop.
New Commands
New Structures
New Bitmasks
New Enum Constants
VK_KHR_WIN32_SURFACE_EXTENSION_NAME
VK_KHR_WIN32_SURFACE_SPEC_VERSION
- Extending VkStructureType:
VK_STRUCTURE_TYPE_WIN32_SURFACE_CREATE_INFO_KHR
Issues
1) Does Win32 need a way to query for compatibility between a particular physical device and a specific screen? Compatibility between a physical device and a window generally only depends on what screen the window is on. However, there is not an obvious way to identify a screen without already having a window on the screen.
RESOLVED: No. While it may be useful, there is not a clear way to do this on Win32. However, a method was added to query support for presenting to the windows desktop as a whole.
2) If a native window object (HWND
) is used by one graphics API, and
then is later used by a different graphics API (one of which is Vulkan), can
these uses interfere with each other?
RESOLVED: Yes.
Uses of a window object by multiple graphics APIs results in undefined: behavior. Such behavior may succeed when using one Vulkan implementation but fail when using a different Vulkan implementation. Potential failures include:
- Creating then destroying a flip presentation model DXGI swapchain on a window object can prevent vkCreateSwapchainKHR from succeeding on the same window object.
- Creating then destroying a VkSwapchainKHR on a window object can prevent creation of a bitblt model DXGI swapchain on the same window object.
- Creating then destroying a VkSwapchainKHR on a window object can
effectively
SetPixelFormat
to a different format than the format chosen by an OpenGL application. - Creating then destroying a VkSwapchainKHR on a window object on one VkPhysicalDevice can prevent vkCreateSwapchainKHR from succeeding on the same window object, but on a different VkPhysicalDevice that is associated with a different Vulkan ICD.
In all cases the problem can be worked around by creating a new window object.
Technical details include:
- Creating a DXGI swapchain over a window object can alter the object for
the remainder of its lifetime.
The alteration persists even after the DXGI swapchain has been
destroyed.
This alteration can make it impossible for a conformant Vulkan
implementation to create a VkSwapchainKHR over the same window
object.
Mention of this alteration can be found in the remarks section of the
MSDN documentation for
DXGI_SWAP_EFFECT
. - Calling GDI’s
SetPixelFormat
(needed by OpenGL’s WGL layer) on a window object alters the object for the remainder of its lifetime. The MSDN documentation forSetPixelFormat
explains that a window object’s pixel format can be set only one time. - Creating a VkSwapchainKHR over a window object can alter the object for its remaining lifetime. Either of the above alterations may occur as a side effect of vkCreateSwapchainKHR.
Version History
- Revision 1, 2015-09-23 (Jesse Hall)
- Initial draft, based on the previous contents of VK_EXT_KHR_swapchain (later renamed VK_EXT_KHR_surface).
- Revision 2, 2015-10-02 (James Jones)
- Added presentation support query for win32 desktops.
- Revision 3, 2015-10-26 (Ian Elliott)
- Renamed from VK_EXT_KHR_win32_surface to VK_KHR_win32_surface.
- Revision 4, 2015-11-03 (Daniel Rakos)
- Added allocation callbacks to vkCreateWin32SurfaceKHR.
- Revision 5, 2015-11-28 (Daniel Rakos)
- Updated the surface create function to take a pCreateInfo structure.
- Revision 6, 2017-04-24 (Jeff Juliano)
- Add issue 2 addressing reuse of a native window object in a different Graphics API, or by a different Vulkan ICD.