128 lines
6.4 KiB
Plaintext
128 lines
6.4 KiB
Plaintext
/*!
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@page compat Standards conformance
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This chapter 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 wishing to deploy their applications on machines
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with varied specifications.
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Note that the information in this appendix is not a part of the API
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specification but merely list some of the preconditions for certain parts of the
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API to function on a given machine. As such, any part of it may change in
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future versions without this being considered a breaking API change.
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@section compat_wm ICCCM and EWMH conformance
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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 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` protocol to tell the window manager to make
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the GLFW window fullscreen. If the running window manager does not support this
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protocol, fullscreen windows may not work properly. GLFW has a fallback code
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path in case this protocol is unavailable, but every window manager behaves
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slightly differently in this regard.
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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 `GLXFBConfig` API to enumerate and select framebuffer pixel
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formats. This requires either GLX 1.3 or greater, or the `GLX_SGIX_fbconfig`
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extension. Where both are available, the SGIX extension is preferred. If
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neither is available, GLFW will be unable to create windows.
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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 a non-zero value 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 zero, or setting `GLFW_CLIENT_API` to
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anything but `GLFW_OPENGL_API` will cause @ref glfwCreateWindow to fail.
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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 a non-zero value 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 zero will cause @ref glfwCreateWindow
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to fail.
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@section cmopat_osx OpenGL 3.2 on Mac OS X
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Support for OpenGL 3.0 and above was introduced with Mac OS X 10.7, and even
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then only forward-compatible OpenGL 3.2 core profile contexts are supported.
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There is also still no mechanism for requesting debug contexts. Versions of
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Mac OS X earlier than 10.7 support at most OpenGL version 2.1.
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Because of this, on Mac OS X 10.7, the `GLFW_CONTEXT_VERSION_MAJOR` and
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`GLFW_CONTEXT_VERSION_MINOR` hints will fail if given a version above 3.2, the
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`GLFW_OPENGL_FORWARD_COMPAT` is required for creating OpenGL 3.2 contexts, the
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`GLFW_OPENGL_DEBUG_CONTEXT` hint is ignored and setting the
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`GLFW_OPENGL_PROFILE` hint to anything except `GLFW_OPENGL_CORE_PROFILE` will
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cause @ref glfwCreateWindow to fail.
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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, the
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`GLFW_OPENGL_DEBUG_CONTEXT` hint will have no effect, and setting the
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`GLFW_OPENGL_PROFILE` or `GLFW_OPENGL_FORWARD_COMPAT` hints to a non-zero value
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will cause @ref glfwCreateWindow to fail.
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*/
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