180 lines
8.8 KiB
Plaintext
180 lines
8.8 KiB
Plaintext
/*!
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@page compat 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](http://www.tronche.com/gui/x/icccm/)
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(ICCCM) and
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[Extended Window Manager Hints](http://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](http://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](http://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 XInput 2 extension to provide sub-pixel cursor motion events. If
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the running X server does not support this version of this extension, cursor
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motion will be snapped to the pixel grid.
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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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@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 `GL_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` will cause @ref
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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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@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 `GL_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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@section compat_osx OpenGL 3.2 and later on OS X
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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. Versions of Mac OS X earlier than 10.7 support at most OpenGL
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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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`GL_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 and the
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`GLFW_OPENGL_DEBUG_CONTEXT` hint is 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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*/
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