282 lines
14 KiB
Plaintext
282 lines
14 KiB
Plaintext
/*!
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@page compat_guide Standards conformance
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@tableofcontents
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This guide describes the various API extensions used by this version of GLFW.
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It lists what are essentially implementation details, but which are nonetheless
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vital knowledge for developers intending to deploy their applications on a wide
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range of machines.
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The information in this guide is not a part of GLFW API, but merely
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preconditions for some parts of the library to function on a given machine. Any
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part of this information may change in future versions of GLFW and that will not
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be considered a breaking API change.
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@section compat_x11 X11 extensions, protocols and IPC standards
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As GLFW uses Xlib directly, without any intervening toolkit
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library, it has sole responsibility for interacting well with the many and
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varied window managers in use on Unix-like systems. In order for applications
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and window managers to work well together, a number of standards and
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conventions have been developed that regulate behavior outside the scope of the
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X11 API; most importantly the
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[Inter-Client Communication Conventions Manual](https://www.tronche.com/gui/x/icccm/)
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(ICCCM) and
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[Extended Window Manager Hints](https://standards.freedesktop.org/wm-spec/wm-spec-latest.html)
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(EWMH) standards.
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GLFW uses the `_MOTIF_WM_HINTS` window property to support borderless windows.
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If the running window manager does not support this property, the
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`GLFW_DECORATED` hint will have no effect.
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GLFW uses the ICCCM `WM_DELETE_WINDOW` protocol to intercept the user
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attempting to close the GLFW window. If the running window manager does not
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support this protocol, the close callback will never be called.
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GLFW uses the EWMH `_NET_WM_PING` protocol, allowing the window manager notify
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the user when the application has stopped responding, i.e. when it has ceased to
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process events. If the running window manager does not support this protocol,
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the user will not be notified if the application locks up.
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GLFW uses the EWMH `_NET_WM_STATE_FULLSCREEN` window state to tell the window
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manager to make the GLFW window full screen. If the running window manager does
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not support this state, full screen windows may not work properly. GLFW has
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a fallback code path in case this state is unavailable, but every window manager
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behaves slightly differently in this regard.
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GLFW uses the EWMH `_NET_WM_BYPASS_COMPOSITOR` window property to tell a
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compositing window manager to un-redirect full screen GLFW windows. If the
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running window manager uses compositing but does not support this property then
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additional copying may be performed for each buffer swap of full screen windows.
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GLFW uses the
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[clipboard manager protocol](https://www.freedesktop.org/wiki/ClipboardManager/)
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to push a clipboard string (i.e. selection) owned by a GLFW window about to be
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destroyed to the clipboard manager. If there is no running clipboard manager,
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the clipboard string will be unavailable once the window has been destroyed.
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GLFW uses the
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[X drag-and-drop protocol](https://www.freedesktop.org/wiki/Specifications/XDND/)
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to provide file drop events. If the application originating the drag does not
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support this protocol, drag and drop will not work.
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GLFW uses the XRandR 1.3 extension to provide multi-monitor support. If the
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running X server does not support this version of this extension, multi-monitor
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support will not function and only a single, desktop-spanning monitor will be
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reported.
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GLFW uses the XRandR 1.3 and Xf86vidmode extensions to provide gamma ramp
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support. If the running X server does not support either or both of these
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extensions, gamma ramp support will not function.
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GLFW uses the Xkb extension and detectable auto-repeat to provide keyboard
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input. If the running X server does not support this extension, a non-Xkb
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fallback path is used.
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GLFW uses the XInput2 extension to provide raw, non-accelerated mouse motion
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when the cursor is disabled. If the running X server does not support this
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extension, regular accelerated mouse motion will be used.
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GLFW uses both the XRender extension and the compositing manager to support
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transparent window framebuffers. If the running X server does not support this
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extension or there is no running compositing manager, the
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`GLFW_TRANSPARENT_FRAMEBUFFER` framebuffer hint will have no effect.
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@section compat_wayland Wayland protocols and IPC standards
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As GLFW uses libwayland directly, without any intervening toolkit library, it
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has sole responsibility for interacting well with every compositor in use on
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Unix-like systems. Most of the features are provided by the core protocol,
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while cursor support is provided by the libwayland-cursor helper library, EGL
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integration by libwayland-egl, and keyboard handling by
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[libxkbcommon](https://xkbcommon.org/). In addition, GLFW uses some protocols
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from wayland-protocols to provide additional features if the compositor
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supports them.
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GLFW uses xkbcommon 0.5.0 to provide compose key support. When it has been
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built against an older xkbcommon, the compose key will be disabled even if it
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has been configured in the compositor.
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GLFW uses the [xdg-shell
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protocol](https://cgit.freedesktop.org/wayland/wayland-protocols/tree/stable/xdg-shell/xdg-shell.xml)
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to provide better window management. This protocol is part of
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wayland-protocols 1.12, and mandatory at build time.
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GLFW uses the [relative pointer
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protocol](https://cgit.freedesktop.org/wayland/wayland-protocols/tree/unstable/relative-pointer/relative-pointer-unstable-v1.xml)
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alongside the [pointer constraints
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protocol](https://cgit.freedesktop.org/wayland/wayland-protocols/tree/unstable/pointer-constraints/pointer-constraints-unstable-v1.xml)
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to implement disabled cursor. These two protocols are part of
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wayland-protocols 1.1, and mandatory at build time. If the running compositor
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does not support both of these protocols, disabling the cursor will have no
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effect.
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GLFW uses the [idle inhibit
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protocol](https://cgit.freedesktop.org/wayland/wayland-protocols/tree/unstable/idle-inhibit/idle-inhibit-unstable-v1.xml)
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to prohibit the screensaver from starting. This protocol is part of
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wayland-protocols 1.6, and mandatory at build time. If the running compositor
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does not support this protocol, the screensaver may start even for full screen
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windows.
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GLFW uses the [xdg-decoration
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protocol](https://cgit.freedesktop.org/wayland/wayland-protocols/tree/unstable/xdg-decoration/xdg-decoration-unstable-v1.xml)
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to request decorations to be drawn around its windows. This protocol is part
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of wayland-protocols 1.15, and mandatory at build time. If the running
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compositor does not support this protocol, a very simple frame will be drawn by
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GLFW itself, using the [viewporter
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protocol](https://cgit.freedesktop.org/wayland/wayland-protocols/tree/stable/viewporter/viewporter.xml)
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alongside
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[subsurfaces](https://cgit.freedesktop.org/wayland/wayland/tree/protocol/wayland.xml#n2598).
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This protocol is part of wayland-protocols 1.4, and mandatory at build time.
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If the running compositor does not support this protocol either, no decorations
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will be drawn around windows.
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@section compat_glx GLX extensions
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The GLX API is the default API used to create OpenGL contexts on Unix-like
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systems using the X Window System.
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GLFW uses the GLX 1.3 `GLXFBConfig` functions to enumerate and select framebuffer pixel
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formats. If GLX 1.3 is not supported, @ref glfwInit will fail.
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GLFW uses the `GLX_MESA_swap_control,` `GLX_EXT_swap_control` and
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`GLX_SGI_swap_control` extensions to provide vertical retrace synchronization
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(or _vsync_), in that order of preference. Where none of these extension are
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available, calling @ref glfwSwapInterval will have no effect.
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GLFW uses the `GLX_ARB_multisample` extension to create contexts with
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multisampling anti-aliasing. Where this extension is unavailable, the
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`GLFW_SAMPLES` hint will have no effect.
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GLFW uses the `GLX_ARB_create_context` extension when available, even when
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creating OpenGL contexts of version 2.1 and below. Where this extension is
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unavailable, the `GLFW_CONTEXT_VERSION_MAJOR` and `GLFW_CONTEXT_VERSION_MINOR`
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hints will only be partially supported, the `GLFW_OPENGL_DEBUG_CONTEXT` hint
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will have no effect, and setting the `GLFW_OPENGL_PROFILE` or
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`GLFW_OPENGL_FORWARD_COMPAT` hints to `GLFW_TRUE` will cause @ref
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glfwCreateWindow to fail.
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GLFW uses the `GLX_ARB_create_context_profile` extension to provide support for
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context profiles. Where this extension is unavailable, setting the
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`GLFW_OPENGL_PROFILE` hint to anything but `GLFW_OPENGL_ANY_PROFILE`, or setting
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`GLFW_CLIENT_API` to anything but `GLFW_OPENGL_API` or `GLFW_NO_API` will cause
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@ref glfwCreateWindow to fail.
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GLFW uses the `GLX_ARB_context_flush_control` extension to provide control over
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whether a context is flushed when it is released (made non-current). Where this
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extension is unavailable, the `GLFW_CONTEXT_RELEASE_BEHAVIOR` hint will have no
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effect and the context will always be flushed when released.
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GLFW uses the `GLX_ARB_framebuffer_sRGB` and `GLX_EXT_framebuffer_sRGB`
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extensions to provide support for sRGB framebuffers. Where both of these
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extensions are unavailable, the `GLFW_SRGB_CAPABLE` hint will have no effect.
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@section compat_wgl WGL extensions
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The WGL API is used to create OpenGL contexts on Microsoft Windows and other
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implementations of the Win32 API, such as Wine.
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GLFW uses either the `WGL_EXT_extension_string` or the
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`WGL_ARB_extension_string` extension to check for the presence of all other WGL
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extensions listed below. If both are available, the EXT one is preferred. If
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neither is available, no other extensions are used and many GLFW features
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related to context creation will have no effect or cause errors when used.
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GLFW uses the `WGL_EXT_swap_control` extension to provide vertical retrace
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synchronization (or _vsync_). Where this extension is unavailable, calling @ref
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glfwSwapInterval will have no effect.
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GLFW uses the `WGL_ARB_pixel_format` and `WGL_ARB_multisample` extensions to
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create contexts with multisampling anti-aliasing. Where these extensions are
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unavailable, the `GLFW_SAMPLES` hint will have no effect.
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GLFW uses the `WGL_ARB_create_context` extension when available, even when
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creating OpenGL contexts of version 2.1 and below. Where this extension is
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unavailable, the `GLFW_CONTEXT_VERSION_MAJOR` and `GLFW_CONTEXT_VERSION_MINOR`
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hints will only be partially supported, the `GLFW_OPENGL_DEBUG_CONTEXT` hint
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will have no effect, and setting the `GLFW_OPENGL_PROFILE` or
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`GLFW_OPENGL_FORWARD_COMPAT` hints to `GLFW_TRUE` will cause @ref
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glfwCreateWindow to fail.
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GLFW uses the `WGL_ARB_create_context_profile` extension to provide support for
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context profiles. Where this extension is unavailable, setting the
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`GLFW_OPENGL_PROFILE` hint to anything but `GLFW_OPENGL_ANY_PROFILE` will cause
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@ref glfwCreateWindow to fail.
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GLFW uses the `WGL_ARB_context_flush_control` extension to provide control over
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whether a context is flushed when it is released (made non-current). Where this
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extension is unavailable, the `GLFW_CONTEXT_RELEASE_BEHAVIOR` hint will have no
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effect and the context will always be flushed when released.
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GLFW uses the `WGL_ARB_framebuffer_sRGB` and `WGL_EXT_framebuffer_sRGB`
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extensions to provide support for sRGB framebuffers. Where both of these
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extension are unavailable, the `GLFW_SRGB_CAPABLE` hint will have no effect.
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@section compat_osx OpenGL on macOS
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Support for OpenGL 3.2 and above was introduced with OS X 10.7 and even then
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only forward-compatible, core profile contexts are supported. Support for
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OpenGL 4.1 was introduced with OS X 10.9, also limited to forward-compatible,
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core profile contexts. There is also still no mechanism for requesting debug
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contexts or no-error contexts. Versions of Mac OS X earlier than 10.7 support
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at most OpenGL version 2.1.
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Because of this, on OS X 10.7 and later, the `GLFW_CONTEXT_VERSION_MAJOR` and
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`GLFW_CONTEXT_VERSION_MINOR` hints will cause @ref glfwCreateWindow to fail if
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given version 3.0 or 3.1. The `GLFW_OPENGL_FORWARD_COMPAT` hint must be set to
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`GLFW_TRUE` and the `GLFW_OPENGL_PROFILE` hint must be set to
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`GLFW_OPENGL_CORE_PROFILE` when creating OpenGL 3.2 and later contexts. The
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`GLFW_OPENGL_DEBUG_CONTEXT` and `GLFW_CONTEXT_NO_ERROR` hints are ignored.
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Also, on Mac OS X 10.6 and below, the `GLFW_CONTEXT_VERSION_MAJOR` and
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`GLFW_CONTEXT_VERSION_MINOR` hints will fail if given a version above 2.1,
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setting the `GLFW_OPENGL_PROFILE` or `GLFW_OPENGL_FORWARD_COMPAT` hints to
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a non-default value will cause @ref glfwCreateWindow to fail and the
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`GLFW_OPENGL_DEBUG_CONTEXT` hint is ignored.
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@section compat_vulkan Vulkan loader and API
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By default, GLFW uses the standard system-wide Vulkan loader to access the
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Vulkan API on all platforms except macOS. This is installed by both graphics
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drivers and Vulkan SDKs. If either the loader or at least one minimally
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functional ICD is missing, @ref glfwVulkanSupported will return `GLFW_FALSE` and
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all other Vulkan-related functions will fail with an @ref GLFW_API_UNAVAILABLE
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error.
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@section compat_wsi Vulkan WSI extensions
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The Vulkan WSI extensions are used to create Vulkan surfaces for GLFW windows on
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all supported platforms.
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GLFW uses the `VK_KHR_surface` and `VK_KHR_win32_surface` extensions to create
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surfaces on Microsoft Windows. If any of these extensions are not available,
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@ref glfwGetRequiredInstanceExtensions will return an empty list and window
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surface creation will fail.
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GLFW uses the `VK_KHR_surface` and either the `VK_MVK_macos_surface` or
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`VK_EXT_metal_surface` extensions to create surfaces on macOS. If any of these
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extensions are not available, @ref glfwGetRequiredInstanceExtensions will
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return an empty list and window surface creation will fail.
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GLFW uses the `VK_KHR_surface` and either the `VK_KHR_xlib_surface` or
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`VK_KHR_xcb_surface` extensions to create surfaces on X11. If `VK_KHR_surface`
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or both `VK_KHR_xlib_surface` and `VK_KHR_xcb_surface` are not available, @ref
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glfwGetRequiredInstanceExtensions will return an empty list and window surface
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creation will fail.
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GLFW uses the `VK_KHR_surface` and `VK_KHR_wayland_surface` extensions to create
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surfaces on Wayland. If any of these extensions are not available, @ref
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glfwGetRequiredInstanceExtensions will return an empty list and window surface
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creation will fail.
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*/
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