VulkanHub

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 for SetPixelFormat 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.