202 lines
7.0 KiB
Plaintext
202 lines
7.0 KiB
Plaintext
/*!
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@page vulkan Vulkan guide
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@tableofcontents
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This guide is intended to fill the gaps between the [Vulkan
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documentation](https://www.khronos.org/vulkan/) and the rest of the GLFW
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documentation and is not a replacement for either. It assumes some familiarity
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with Vulkan concepts like loaders, devices, queues and surfaces.
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To develop for Vulkan you should install an SDK for your platform, for example
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the [LunarG Vulkan SDK](https://vulkan.lunarg.com/). Apart from the headers and
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libraries, it also provides the validation layers necessary for development.
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The GLFW library does not need the Vulkan SDK to enable support for Vulkan.
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However, any Vulkan-specific test and example programs are built only if the
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CMake files find a Vulkan SDK.
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@section vulkan_include Including the Vulkan and GLFW header files
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To include the Vulkan header, define [GLFW_INCLUDE_VULKAN](@ref build_macros)
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before including the GLFW header.
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@code
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#define GLFW_INCLUDE_VULKAN
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#include <GLFW/glfw3.h>
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@endcode
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If you want to include the Vulkan header from a custom location or use your own
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custom Vulkan header then you need to include them before the GLFW header.
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@code
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#include <path/to/vulkan.h>
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#include <GLFW/glfw3.h>
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@endcode
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Unless a Vulkan header is included, either by the GLFW header or above it, any
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GLFW functions that take or return Vulkan types will not be declared.
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The `VK_USE_PLATFORM_*_KHR` macros do not need to be defined for the Vulkan part
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of GLFW to work. Define them only if you are using these extensions directly.
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@section vulkan_support Querying for Vulkan support
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If you are linking directly against the Vulkan loader then you can skip this
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section. The canonical desktop loader library exports all Vulkan core and
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Khronos extension functions, allowing them to be called directly.
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If you are loading the Vulkan loader dynamically instead of linking directly
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against it, you can check for the availability of a loader with @ref
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glfwVulkanSupported.
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@code
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if (glfwVulkanSupported())
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{
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// Vulkan is available, at least for compute
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}
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@endcode
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This function returns `GLFW_TRUE` if the Vulkan loader was found. This check is
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performed by @ref glfwInit.
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If no loader was found, calling any other Vulkan related GLFW function will
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generate a @ref GLFW_API_UNAVAILABLE error.
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@subsection vulkan_proc Querying Vulkan function pointers
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To load any Vulkan core or extension function from the found loader, call @ref
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glfwGetInstanceProcAddress. To load functions needed for instance creation,
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pass `NULL` as the instance.
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@code
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PFN_vkCreateInstance pfnCreateInstance = (PFN_vkCreateInstance)
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glfwGetInstanceProcAddress(NULL, "vkCreateInstance");
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@endcode
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Once you have created an instance, you can load from it all other Vulkan core
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functions and functions from any instance extensions you enabled.
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@code
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PFN_vkCreateDevice pfnCreateDevice = (PFN_vkCreateDevice)
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glfwGetInstanceProcAddress(instance, "vkCreateDevice");
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@endcode
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This function in turn calls `vkGetInstanceProcAddr`. If that fails, the
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function falls back to a platform-specific query of the Vulkan loader (i.e.
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`dlsym` or `GetProcAddress`). If that also fails, the function returns `NULL`.
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For more information about `vkGetInstanceProcAddr`, see the Vulkan
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documentation.
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Vulkan also provides `vkGetDeviceProcAddr` for loading device-specific versions
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of Vulkan function. This function can be retrieved from an instance with @ref
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glfwGetInstanceProcAddress.
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@code
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PFN_vkGetDeviceProcAddr pfnGetDeviceProcAddr = (PFN_vkGetDeviceProcAddr)
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glfwGetInstanceProcAddress(instance, "vkGetDeviceProcAddr");
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@endcode
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Device-specific functions may execute a little bit faster, due to not having to
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dispatch internally based on the device passed to them. For more information
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about `vkGetDeviceProcAddr`, see the Vulkan documentation.
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@section vulkan_ext Querying required Vulkan extensions
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To do anything useful with Vulkan you need to create an instance. If you want
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to use Vulkan to render to a window, you must enable the instance extensions
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GLFW requires to create Vulkan surfaces.
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To query the instance extensions required, call @ref
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glfwGetRequiredInstanceExtensions.
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@code
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int count;
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const char** extensions = glfwGetRequiredInstanceExtensions(&count);
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@endcode
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These extensions must all be enabled when creating instances that are going to
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be passed to @ref glfwGetPhysicalDevicePresentationSupport and @ref
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glfwCreateWindowSurface. The set of extensions will vary depending on platform
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and may also vary depending on graphics drivers and other factors.
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If it fails it will return `NULL` and GLFW will not be able to create Vulkan
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window surfaces. You can still use Vulkan for off-screen rendering and compute
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work.
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The returned array will always contain `VK_KHR_surface`, so if you don't
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require any additional extensions you can pass this list directly to the
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`VkInstanceCreateInfo` struct.
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@code
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VkInstanceCreateInfo ici;
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memset(&ici, 0, sizeof(ici));
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ici.enabledExtensionCount = count;
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ici.ppEnabledExtensionNames = extensions;
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...
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@endcode
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Additional extensions may be required by future versions of GLFW. You should
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check whether any extensions you wish to enable are already in the returned
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array, as it is an error to specify an extension more than once in the
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`VkInstanceCreateInfo` struct.
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@section vulkan_present Querying for Vulkan presentation support
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Not every queue family of every Vulkan device can present images to surfaces.
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To check whether a specific queue family of a physical device supports image
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presentation without first having to create a window and surface, call @ref
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glfwGetPhysicalDevicePresentationSupport.
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@code
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if (glfwGetPhysicalDevicePresentationSupport(instance, physical_device, queue_family_index))
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{
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// Queue family supports image presentation
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}
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@endcode
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The `VK_KHR_surface` extension additionally provides the
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`vkGetPhysicalDeviceSurfaceSupportKHR` function, which performs the same test on
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an existing Vulkan surface.
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@section vulkan_window Creating the window
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Unless you will be using OpenGL or OpenGL ES with the same window as Vulkan,
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there is no need to create a context. You can disable context creation by
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setting the [GLFW_CLIENT_API](@ref window_hints_ctx) hint to `GLFW_NO_API`.
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@code
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glfwWindowHint(GLFW_CLIENT_API, GLFW_NO_API);
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GLFWwindow* window = glfwCreateWindow(640, 480, "Window Title", NULL, NULL);
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@endcode
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See @ref context_less for more information.
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@section vulkan_surface Creating a Vulkan window surface
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You can create a Vulkan surface (as defined by the `VK_KHR_surface` extension)
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for a GLFW window with @ref glfwCreateWindowSurface.
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@code
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VkSurfaceKHR surface;
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VkResult err = glfwCreateWindowSurface(instance, window, NULL, &surface);
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if (err)
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{
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// Window surface creation failed
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}
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@endcode
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It is your responsibility to destroy the surface. GLFW does not destroy it for
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you. Call `vkDestroySurfaceKHR` function from the same extension to destroy it.
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*/
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