Author: The Khronos® Vulkan Working Group

# Vulkan® 1.3.235 - A Specification (with all registered extensions)

The Khronos® Vulkan Working Group
version 1.3.235, 2022-11-19 16:32:39Z
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## Appendix G: API Boilerplate

This appendix defines Vulkan API features that are infrastructure required for a complete functional description of Vulkan, but do not logically belong elsewhere in the Specification.

### Vulkan Header Files

Vulkan is defined as an API in the C99 language. Khronos provides a corresponding set of header files for applications using the API, which may be used in either C or C++ code. The interface descriptions in the specification are the same as the interfaces defined in these header files, and both are derived from the `vk.xml` XML API Registry, which is the canonical machine-readable description of the Vulkan API. The Registry, scripts used for processing it into various forms, and documentation of the registry schema are available as described at https://registry.khronos.org/vulkan/#apiregistry .

Language bindings for other languages can be defined using the information in the Specification and the Registry. Khronos does not provide any such bindings, but third-party developers have created some additional bindings.

#### Vulkan Combined API Header `vulkan.h` (Informative)

Applications normally will include the header `vulkan.h`. In turn, `vulkan.h` always includes the following headers:

- `vk_platform.h`, defining platform-specific macros and headers.

- `vulkan_core.h`, defining APIs for the Vulkan core and all registered extensions other than window system-specific and provisional extensions, which are included in separate header files.

In addition, specific preprocessor macros defined at the time `vulkan.h` is included cause header files for the corresponding window system-specific and provisional interfaces to be included, as described below.

#### Vulkan Platform-Specific Header `vk_platform.h` (Informative)

Platform-specific macros and interfaces are defined in `vk_platform.h`. These macros are used to control platform-dependent behavior, and their exact definitions are under the control of specific platforms and Vulkan implementations.

##### Platform-Specific Calling Conventions

On many platforms the following macros are empty strings, causing platform- and compiler-specific default calling conventions to be used.

`VKAPI_ATTR` is a macro placed before the return type in Vulkan API function declarations. This macro controls calling conventions for C++11 and GCC/Clang-style compilers.

`VKAPI_CALL` is a macro placed after the return type in Vulkan API function declarations. This macro controls calling conventions for MSVC-style compilers.

`VKAPI_PTR` is a macro placed between the '(' and '*' in Vulkan API function pointer declarations. This macro also controls calling conventions, and typically has the same definition as `VKAPI_ATTR` or `VKAPI_CALL`, depending on the compiler.

With these macros, a Vulkan function declaration takes the form of:

    VKAPI_ATTR <return_type> VKAPI_CALL <command_name>(<command_parameters>);

Additionally, a Vulkan function pointer type declaration takes the form of:

    typedef <return_type> (VKAPI_PTR *PFN_<command_name>)(<command_parameters>);

##### Platform-Specific Header Control

If the `VK_NO_STDINT_H` macro is defined by the application at compile time, extended integer types used by the Vulkan API, such as `uint8_t`, must also be defined by the application. Otherwise, the Vulkan headers will not compile. If `VK_NO_STDINT_H` is not defined, the system `<stdint.h>` is used to define these types. There is a fallback path when Microsoft Visual Studio version 2008 and earlier versions are detected at compile time.

If the `VK_NO_STDDEF_H` macro is defined by the application at compile time, `size_t`, must also be defined by the application. Otherwise, the Vulkan headers will not compile. If `VK_NO_STDDEF_H` is not defined, the system `<stddef.h>` is used to define this type.

#### Vulkan Core API Header `vulkan_core.h`

Applications that do not make use of window system-specific extensions may simply include `vulkan_core.h` instead of `vulkan.h`, although there is usually no reason to do so. In addition to the Vulkan API, `vulkan_core.h` also defines a small number of C preprocessor macros that are described below.

##### Vulkan Header File Version Number

`VK_HEADER_VERSION` is the version number of the `vulkan_core.h` header. This value is kept synchronized with the patch version of the released Specification.

    // Provided by VK_VERSION_1_0
    // Version of this file
    #define VK_HEADER_VERSION 235

`VK_HEADER_VERSION_COMPLETE` is the complete version number of the `vulkan_core.h` header, comprising the major, minor, and patch versions. The major/minor values are kept synchronized with the complete version of the released Specification. This value is intended for use by automated tools to identify exactly which version of the header was used during their generation.

Applications should not use this value as their VkApplicationInfo::`apiVersion`. Instead applications should explicitly select a specific fixed major/minor API version using, for example, one of the `VK_API_VERSION_`*_* values.

    // Provided by VK_VERSION_1_0
    // Complete version of this file
    #define VK_HEADER_VERSION_COMPLETE VK_MAKE_API_VERSION(0, 1, 3, VK_HEADER_VERSION)

`VK_API_VERSION` is now commented out of `vulkan_core.h` and cannot be used.

    // Provided by VK_VERSION_1_0
    // DEPRECATED: This define has been removed. Specific version defines (e.g. VK_API_VERSION_1_0), or the VK_MAKE_VERSION macro, should be used instead.
    //#define VK_API_VERSION VK_MAKE_VERSION(1, 0, 0) // Patch version should always be set to 0

##### Vulkan Handle Macros

`VK_DEFINE_HANDLE` defines a dispatchable handle type.

    // Provided by VK_VERSION_1_0

    #define VK_DEFINE_HANDLE(object) typedef struct object##_T* object;

- `object` is the name of the resulting C type.

The only dispatchable handle types are those related to device and instance management, such as VkDevice.

`VK_DEFINE_NON_DISPATCHABLE_HANDLE` defines a non-dispatchable handle type.

    // Provided by VK_VERSION_1_0

    #ifndef VK_DEFINE_NON_DISPATCHABLE_HANDLE
        #if (VK_USE_64_BIT_PTR_DEFINES==1)
            #define VK_DEFINE_NON_DISPATCHABLE_HANDLE(object) typedef struct object##_T *object;
        #else
            #define VK_DEFINE_NON_DISPATCHABLE_HANDLE(object) typedef uint64_t object;
        #endif
    #endif

- `object` is the name of the resulting C type.

Most Vulkan handle types, such as VkBuffer, are non-dispatchable.

| Note The `vulkan_core.h` header allows the VK_DEFINE_NON_DISPATCHABLE_HANDLE and VK_NULL_HANDLE definitions to be overridden by the application. If VK_DEFINE_NON_DISPATCHABLE_HANDLE is already defined when `vulkan_core.h` is compiled, the default definitions for VK_DEFINE_NON_DISPATCHABLE_HANDLE and VK_NULL_HANDLE are skipped. This allows the application to define a binary-compatible custom handle which may provide more type-safety or other features needed by the application. Applications must not define handles in a way that is not binary compatible - where binary compatibility is platform dependent.

`VK_NULL_HANDLE` is a reserved value representing a non-valid object handle. It may be passed to and returned from Vulkan commands only when specifically allowed.

    // Provided by VK_VERSION_1_0

    #ifndef VK_DEFINE_NON_DISPATCHABLE_HANDLE
        #if (VK_USE_64_BIT_PTR_DEFINES==1)
            #if (defined(__cplusplus) && (__cplusplus >= 201103L)) || (defined(_MSVC_LANG) && (_MSVC_LANG >= 201103L))
                #define VK_NULL_HANDLE nullptr
            #else
                #define VK_NULL_HANDLE ((void*)0)
            #endif
        #else
            #define VK_NULL_HANDLE 0ULL
        #endif
    #endif
    #ifndef VK_NULL_HANDLE
        #define VK_NULL_HANDLE 0
    #endif

`VK_USE_64_BIT_PTR_DEFINES` defines whether the default non-dispatchable handles are declared using either a 64-bit pointer type or a 64-bit unsigned integer type.

`VK_USE_64_BIT_PTR_DEFINES` is set to '1' to use a 64-bit pointer type or any other value to use a 64-bit unsigned integer type.

    // Provided by VK_VERSION_1_0

    #ifndef VK_USE_64_BIT_PTR_DEFINES
        #if defined(__LP64__) || defined(_WIN64) || (defined(__x86_64__) && !defined(__ILP32__) ) || defined(_M_X64) || defined(__ia64) || defined (_M_IA64) || defined(__aarch64__) || defined(__powerpc64__)
            #define VK_USE_64_BIT_PTR_DEFINES 1
        #else
            #define VK_USE_64_BIT_PTR_DEFINES 0
        #endif
    #endif

| Note The `vulkan_core.h` header allows the `VK_USE_64_BIT_PTR_DEFINES` definition to be overridden by the application. This allows the application to select either a 64-bit pointer type or a 64-bit unsigned integer type for non-dispatchable handles in the case where the predefined preprocessor check does not identify the desired configuration.

| Note This macro was introduced starting with the Vulkan 1.2.174 headers, and its availability can be checked at compile time by requiring ``VK_HEADER_VERSION` >= 174`. It is not available if you are using older headers, such as may be shipped with an older Vulkan SDK. Developers requiring this functionality may wish to include a copy of the current Vulkan headers with their project in this case.

### Window System-Specific Header Control (Informative)

To use a Vulkan extension supporting a platform-specific window system, header files for that window system must be included at compile time, or platform-specific types must be forward-declared. The Vulkan header files are unable to determine whether or not an external header is available at compile time, so platform-specific extensions are provided in separate headers from the core API and platform-independent extensions, allowing applications to decide which ones they need to be defined and how the external headers are included.

Extensions dependent on particular sets of platform headers, or that forward-declare platform-specific types, are declared in a header named for that platform. Before including these platform-specific Vulkan headers, applications must include both `vulkan_core.h` and any external native headers the platform extensions depend on.

As a convenience for applications that do not need the flexibility of separate platform-specific Vulkan headers, `vulkan.h` includes `vulkan_core.h`, and then conditionally includes platform-specific Vulkan headers and the external headers they depend on. Applications control which platform-specific headers are included by #defining macros before including `vulkan.h`.

The correspondence between platform-specific extensions, external headers they require, the platform-specific header which declares them, and the preprocessor macros which enable inclusion by `vulkan.h` are shown in the following table.

Table 98. Window System Extensions and Headers
Extension Name | Window System Name | Platform-specific Header | Required External Headers | Controlling `vulkan.h` Macro
--- | --- | --- | --- | ---
`VK_KHR_android_surface` | Android | `vulkan_android.h` | None | `VK_USE_PLATFORM_ANDROID_KHR`
`VK_KHR_wayland_surface` | Wayland | `vulkan_wayland.h` | `<wayland-client.h>` | `VK_USE_PLATFORM_WAYLAND_KHR`
`VK_KHR_win32_surface`, `VK_KHR_external_memory_win32`, `VK_KHR_win32_keyed_mutex`, `VK_KHR_external_semaphore_win32`, `VK_KHR_external_fence_win32`, `VK_NV_external_memory_win32`, `VK_NV_win32_keyed_mutex` | Microsoft Windows | `vulkan_win32.h` | `<windows.h>` | `VK_USE_PLATFORM_WIN32_KHR`
`VK_KHR_xcb_surface` | X11 Xcb | `vulkan_xcb.h` | `<xcb/xcb.h>` | `VK_USE_PLATFORM_XCB_KHR`
`VK_KHR_xlib_surface` | X11 Xlib | `vulkan_xlib.h` | `<X11/Xlib.h>` | `VK_USE_PLATFORM_XLIB_KHR`
`VK_EXT_directfb_surface` | DirectFB | `vulkan_directfb.h` | `<directfb/directfb.h>` | `VK_USE_PLATFORM_DIRECTFB_EXT`
`VK_EXT_acquire_xlib_display` | X11 XRAndR | `vulkan_xlib_xrandr.h` | `<X11/Xlib.h>`, `<X11/extensions/Xrandr.h>` | `VK_USE_PLATFORM_XLIB_XRANDR_EXT`
`VK_GGP_stream_descriptor_surface`, `VK_GGP_frame_token` | Google Games Platform | `vulkan_ggp.h` | <ggp_c/vulkan_types.h> | `VK_USE_PLATFORM_GGP`
`VK_MVK_ios_surface` | iOS | `vulkan_ios.h` | None | `VK_USE_PLATFORM_IOS_MVK`
`VK_MVK_macos_surface` | macOS | `vulkan_macos.h` | None | `VK_USE_PLATFORM_MACOS_MVK`
`VK_NN_vi_surface` | VI | `vulkan_vi.h` | None | `VK_USE_PLATFORM_VI_NN`
`VK_FUCHSIA_imagepipe_surface` | Fuchsia | `vulkan_fuchsia.h` | `<zircon/types.h>` | `VK_USE_PLATFORM_FUCHSIA`
`VK_EXT_metal_surface` | Metal on CoreAnimation | `vulkan_metal.h` | None | `VK_USE_PLATFORM_METAL_EXT`
`VK_QNX_screen_surface` | QNX Screen | `vulkan_screen.h` | `<screen/screen.h>` | `VK_USE_PLATFORM_SCREEN_QNX`

| Note This section describes the purpose of the headers independently of the specific underlying functionality of the window system extensions themselves. Each extension name will only link to a description of that extension when viewing a specification built with that extension included.

### Provisional Extension Header Control (Informative)

Provisional extensions should not be used in production applications. The functionality defined by such extensions may change in ways that break backwards compatibility between revisions, and before final release of a non-provisional version of that extension.

Provisional extensions are defined in a separate provisional header, `vulkan_beta.h`, allowing applications to decide whether or not to include them. The mechanism is similar to window system-specific headers: before including `vulkan_beta.h`, applications must include `vulkan_core.h`.

| Note Sometimes a provisional extension will include a subset of its interfaces in `vulkan_core.h`. This may occur if the provisional extension is promoted from an existing vendor or EXT extension and some of the existing interfaces are defined as aliases of the provisional extension interfaces. All other interfaces of that provisional extension which are not aliased will be included in `vulkan_beta.h`.

As a convenience for applications, `vulkan.h` conditionally includes `vulkan_beta.h`. Applications can control inclusion of `vulkan_beta.h` by #defining the macro `VK_ENABLE_BETA_EXTENSIONS` before including `vulkan.h`.

| Note Starting in version 1.2.171 of the Specification, all provisional enumerants are protected by the macro `VK_ENABLE_BETA_EXTENSIONS`. Applications needing to use provisional extensions must always define this macro, even if they are explicitly including `vulkan_beta.h`. This is a minor change to behavior, affecting only provisional extensions.

| Note This section describes the purpose of the provisional header independently of the specific provisional extensions which are contained in that header at any given time. The extension appendices for provisional extensions note their provisional status, and link back to this section for more information. Provisional extensions are intended to provide early access for bleeding-edge developers, with the understanding that extension interfaces may change in response to developer feedback. Provisional extensions are very likely to eventually be updated and released as non-provisional extensions, but there is no guarantee this will happen, or how long it will take if it does happen.

### Video Std Headers (Informative)

Performing video coding operations usually involves the application having to provide various parameters, data structures, or other syntax elements specific to the particular video compression standard used, and the associated semantics are covered by the specification of those.

The interface descriptions of these are available in the header files derived from the `video.xml` XML file, which includes a machine-readable definition of data structures and enumerations that are associated with the externally-provided video compression standards, and are non-normatively referred to in the Vulkan Specification.

Table 99. Video Std Headers
Video Std Header Name | Description | Header File | Related Extensions
--- | --- | --- | ---
`vulkan_video_codecs_common` | Codec-independent common definitions | `<vk_video/vulkan_video_codecs_common.h>` | -
`vulkan_video_codec_h264std` | ITU-T H.264 common definitions | `<vk_video/vulkan_video_codec_h264std.h>` | VK_EXT_video_decode_h264, VK_EXT_video_encode_h264
`vulkan_video_codec_h264std_decode` | ITU-T H.264 decode-specific definitions | `<vk_video/vulkan_video_codec_h264std_decode.h>` | VK_EXT_video_decode_h264
`vulkan_video_codec_h264std_encode` | ITU-T H.264 encode-specific definitions | `<vk_video/vulkan_video_codec_h264std_encode.h>` | VK_EXT_video_encode_h264
`vulkan_video_codec_h265std` | ITU-T H.265 common definitions | `<vk_video/vulkan_video_codec_h265std.h>` | VK_EXT_video_decode_h265, VK_EXT_video_encode_h265
`vulkan_video_codec_h265std_decode` | ITU-T H.265 decode-specific definitions | `<vk_video/vulkan_video_codec_h265std_decode.h>` | VK_EXT_video_decode_h265
`vulkan_video_codec_h265std_encode` | ITU-T H.265 encode-specific definitions | `<vk_video/vulkan_video_codec_h265std_encode.h>` | VK_EXT_video_encode_h265