docs/compat.dox - third_party/glfw - Git at Google

 /*!

 @page compat Standards conformance

 @tableofcontents

 This chapter describes the various API extensions used by this version of GLFW.
 It lists what are essentially implementation details, but which are nonetheless
 vital knowledge for developers wishing to deploy their applications on machines
 with varied specifications.

 Note that the information in this appendix is not a part of the API
 specification but merely list some of the preconditions for certain parts of the
 API to function on a given machine.  As such, any part of it may change in
 future versions without this being considered a breaking API change.

 @section compat_wm ICCCM and EWMH conformance

 As GLFW uses Xlib, directly, without any intervening toolkit
 library, it has sole responsibility for interacting well with the many and
 varied window managers in use on Unix-like systems.  In order for applications
 and window managers to work well together, a number of standards and
 conventions have been developed that regulate behavior outside the scope of the
 X11 API; most importantly the
 [Inter-Client Communication Conventions Manual](http://www.tronche.com/gui/x/icccm/)
 (ICCCM) and
 [Extended Window Manager Hints](http://standards.freedesktop.org/wm-spec/wm-spec-latest.html)
 (EWMH) standards.

 GLFW uses the ICCCM `WM_DELETE_WINDOW` protocol to intercept the user
 attempting to close the GLFW window.  If the running window manager does not
 support this protocol, the close callback will never be called.

 GLFW uses the EWMH `_NET_WM_PING` protocol, allowing the window manager notify
 the user when the application has stopped responding, i.e. when it has ceased to
 process events.  If the running window manager does not support this protocol,
 the user will not be notified if the application locks up.

 GLFW uses the EWMH `_NET_WM_STATE` protocol to tell the window manager to make
 the GLFW window full screen.  If the running window manager does not support this
 protocol, full screen windows may not work properly.  GLFW has a fallback code
 path in case this protocol is unavailable, but every window manager behaves
 slightly differently in this regard.

 @section compat_glx GLX extensions

 The GLX API is the default API used to create OpenGL contexts on Unix-like
 systems using the X Window System.

 GLFW uses the `GLXFBConfig` API to enumerate and select framebuffer pixel
 formats.  This requires either GLX 1.3 or greater, or the `GLX_SGIX_fbconfig`
 extension.  Where both are available, the SGIX extension is preferred.  If
 neither is available, GLFW will be unable to create windows.

 GLFW uses the `GLX_MESA_swap_control,` `GLX_EXT_swap_control` and
 `GLX_SGI_swap_control` extensions to provide vertical retrace synchronization
 (or "vsync"), in that order of preference.  Where none of these extension are
 available, calling @ref glfwSwapInterval will have no effect.

 GLFW uses the `GLX_ARB_multisample` extension to create contexts with
 multisampling anti-aliasing.  Where this extension is unavailable, the
 `GLFW_SAMPLES` hint will have no effect.

 GLFW uses the `GLX_ARB_create_context` extension when available, even when
 creating OpenGL contexts of version 2.1 and below.  Where this extension is
 unavailable, the `GLFW_CONTEXT_VERSION_MAJOR` and `GLFW_CONTEXT_VERSION_MINOR`
 hints will only be partially supported, the `GLFW_OPENGL_DEBUG_CONTEXT` hint
 will have no effect, and setting the `GLFW_OPENGL_PROFILE` or
 `GLFW_OPENGL_FORWARD_COMPAT` hints to a non-zero value will cause @ref
 glfwCreateWindow to fail.

 GLFW uses the `GLX_ARB_create_context_profile` extension to provide support for
 context profiles.  Where this extension is unavailable, setting the
 `GLFW_OPENGL_PROFILE` hint to anything but zero, or setting `GLFW_CLIENT_API` to
 anything but `GLFW_OPENGL_API` will cause @ref glfwCreateWindow to fail.

 @section compat_wgl WGL extensions

 The WGL API is used to create OpenGL contexts on Microsoft Windows and other
 implementations of the Win32 API, such as Wine.

 GLFW uses either the `WGL_EXT_extension_string` or the
 `WGL_ARB_extension_string` extension to check for the presence of all other WGL
 extensions listed below.  If both are available, the EXT one is preferred.  If
 neither is available, no other extensions are used and many GLFW features
 related to context creation will have no effect or cause errors when used.

 GLFW uses the `WGL_EXT_swap_control` extension to provide vertical retrace
 synchronization (or 'vsync').  Where this extension is unavailable, calling @ref
 glfwSwapInterval will have no effect.

 GLFW uses the `WGL_ARB_pixel_format` and `WGL_ARB_multisample` extensions to
 create contexts with multisampling anti-aliasing.  Where these extensions are
 unavailable, the `GLFW_SAMPLES` hint will have no effect.

 GLFW uses the `WGL_ARB_create_context` extension when available, even when
 creating OpenGL contexts of version 2.1 and below.  Where this extension is
 unavailable, the `GLFW_CONTEXT_VERSION_MAJOR` and `GLFW_CONTEXT_VERSION_MINOR`
 hints will only be partially supported, the `GLFW_OPENGL_DEBUG_CONTEXT` hint
 will have no effect, and setting the `GLFW_OPENGL_PROFILE` or
 `GLFW_OPENGL_FORWARD_COMPAT` hints to a non-zero value will cause @ref
 glfwCreateWindow to fail.

 GLFW uses the `WGL_ARB_create_context_profile` extension to provide support for
 context profiles.  Where this extension is unavailable, setting the
 `GLFW_OPENGL_PROFILE` hint to anything but zero will cause @ref glfwCreateWindow
 to fail.

 @section cmopat_osx OpenGL 3.2 on Mac OS X

 Support for OpenGL 3.0 and above was introduced with Mac OS X 10.7, and even
 then only forward-compatible OpenGL 3.2 core profile contexts are supported.
 There is also still no mechanism for requesting debug contexts.  Versions of
 Mac OS X earlier than 10.7 support at most OpenGL version 2.1.

 Because of this, on Mac OS X 10.7, the `GLFW_CONTEXT_VERSION_MAJOR` and
 `GLFW_CONTEXT_VERSION_MINOR` hints will fail if given a version above 3.2, the
 `GLFW_OPENGL_FORWARD_COMPAT` is required for creating OpenGL 3.2 contexts, the
 `GLFW_OPENGL_DEBUG_CONTEXT` hint is ignored and setting the
 `GLFW_OPENGL_PROFILE` hint to anything except `GLFW_OPENGL_CORE_PROFILE` will
 cause @ref glfwCreateWindow to fail.

 Also, on Mac OS X 10.6 and below, the `GLFW_CONTEXT_VERSION_MAJOR` and
 `GLFW_CONTEXT_VERSION_MINOR` hints will fail if given a version above 2.1, the
 `GLFW_OPENGL_DEBUG_CONTEXT` hint will have no effect, and setting the
 `GLFW_OPENGL_PROFILE` or `GLFW_OPENGL_FORWARD_COMPAT` hints to a non-zero value
 will cause @ref glfwCreateWindow to fail.

 */
	/*!

	@page compat Standards conformance

	@tableofcontents

	This chapter describes the various API extensions used by this version of GLFW.
	It lists what are essentially implementation details, but which are nonetheless
	vital knowledge for developers wishing to deploy their applications on machines
	with varied specifications.

	Note that the information in this appendix is not a part of the API
	specification but merely list some of the preconditions for certain parts of the
	API to function on a given machine. As such, any part of it may change in
	future versions without this being considered a breaking API change.

	@section compat_wm ICCCM and EWMH conformance

	As GLFW uses Xlib, directly, without any intervening toolkit
	library, it has sole responsibility for interacting well with the many and
	varied window managers in use on Unix-like systems. In order for applications
	and window managers to work well together, a number of standards and
	conventions have been developed that regulate behavior outside the scope of the
	X11 API; most importantly the
	[Inter-Client Communication Conventions Manual](http://www.tronche.com/gui/x/icccm/)
	(ICCCM) and
	[Extended Window Manager Hints](http://standards.freedesktop.org/wm-spec/wm-spec-latest.html)
	(EWMH) standards.

	GLFW uses the ICCCM `WM_DELETE_WINDOW` protocol to intercept the user
	attempting to close the GLFW window. If the running window manager does not
	support this protocol, the close callback will never be called.

	GLFW uses the EWMH `_NET_WM_PING` protocol, allowing the window manager notify
	the user when the application has stopped responding, i.e. when it has ceased to
	process events. If the running window manager does not support this protocol,
	the user will not be notified if the application locks up.

	GLFW uses the EWMH `_NET_WM_STATE` protocol to tell the window manager to make
	the GLFW window full screen. If the running window manager does not support this
	protocol, full screen windows may not work properly. GLFW has a fallback code
	path in case this protocol is unavailable, but every window manager behaves
	slightly differently in this regard.

	@section compat_glx GLX extensions

	The GLX API is the default API used to create OpenGL contexts on Unix-like
	systems using the X Window System.

	GLFW uses the `GLXFBConfig` API to enumerate and select framebuffer pixel
	formats. This requires either GLX 1.3 or greater, or the `GLX_SGIX_fbconfig`
	extension. Where both are available, the SGIX extension is preferred. If
	neither is available, GLFW will be unable to create windows.

	GLFW uses the `GLX_MESA_swap_control,` `GLX_EXT_swap_control` and
	`GLX_SGI_swap_control` extensions to provide vertical retrace synchronization
	(or "vsync"), in that order of preference. Where none of these extension are
	available, calling @ref glfwSwapInterval will have no effect.

	GLFW uses the `GLX_ARB_multisample` extension to create contexts with
	multisampling anti-aliasing. Where this extension is unavailable, the
	`GLFW_SAMPLES` hint will have no effect.

	GLFW uses the `GLX_ARB_create_context` extension when available, even when
	creating OpenGL contexts of version 2.1 and below. Where this extension is
	unavailable, the `GLFW_CONTEXT_VERSION_MAJOR` and `GLFW_CONTEXT_VERSION_MINOR`
	hints will only be partially supported, the `GLFW_OPENGL_DEBUG_CONTEXT` hint
	will have no effect, and setting the `GLFW_OPENGL_PROFILE` or
	`GLFW_OPENGL_FORWARD_COMPAT` hints to a non-zero value will cause @ref
	glfwCreateWindow to fail.

	GLFW uses the `GLX_ARB_create_context_profile` extension to provide support for
	context profiles. Where this extension is unavailable, setting the
	`GLFW_OPENGL_PROFILE` hint to anything but zero, or setting `GLFW_CLIENT_API` to
	anything but `GLFW_OPENGL_API` will cause @ref glfwCreateWindow to fail.

	@section compat_wgl WGL extensions

	The WGL API is used to create OpenGL contexts on Microsoft Windows and other
	implementations of the Win32 API, such as Wine.

	GLFW uses either the `WGL_EXT_extension_string` or the
	`WGL_ARB_extension_string` extension to check for the presence of all other WGL
	extensions listed below. If both are available, the EXT one is preferred. If
	neither is available, no other extensions are used and many GLFW features
	related to context creation will have no effect or cause errors when used.

	GLFW uses the `WGL_EXT_swap_control` extension to provide vertical retrace
	synchronization (or 'vsync'). Where this extension is unavailable, calling @ref
	glfwSwapInterval will have no effect.

	GLFW uses the `WGL_ARB_pixel_format` and `WGL_ARB_multisample` extensions to
	create contexts with multisampling anti-aliasing. Where these extensions are
	unavailable, the `GLFW_SAMPLES` hint will have no effect.

	GLFW uses the `WGL_ARB_create_context` extension when available, even when
	creating OpenGL contexts of version 2.1 and below. Where this extension is
	unavailable, the `GLFW_CONTEXT_VERSION_MAJOR` and `GLFW_CONTEXT_VERSION_MINOR`
	hints will only be partially supported, the `GLFW_OPENGL_DEBUG_CONTEXT` hint
	will have no effect, and setting the `GLFW_OPENGL_PROFILE` or
	`GLFW_OPENGL_FORWARD_COMPAT` hints to a non-zero value will cause @ref
	glfwCreateWindow to fail.

	GLFW uses the `WGL_ARB_create_context_profile` extension to provide support for
	context profiles. Where this extension is unavailable, setting the
	`GLFW_OPENGL_PROFILE` hint to anything but zero will cause @ref glfwCreateWindow
	to fail.

	@section cmopat_osx OpenGL 3.2 on Mac OS X

	Support for OpenGL 3.0 and above was introduced with Mac OS X 10.7, and even
	then only forward-compatible OpenGL 3.2 core profile contexts are supported.
	There is also still no mechanism for requesting debug contexts. Versions of
	Mac OS X earlier than 10.7 support at most OpenGL version 2.1.

	Because of this, on Mac OS X 10.7, the `GLFW_CONTEXT_VERSION_MAJOR` and
	`GLFW_CONTEXT_VERSION_MINOR` hints will fail if given a version above 3.2, the
	`GLFW_OPENGL_FORWARD_COMPAT` is required for creating OpenGL 3.2 contexts, the
	`GLFW_OPENGL_DEBUG_CONTEXT` hint is ignored and setting the
	`GLFW_OPENGL_PROFILE` hint to anything except `GLFW_OPENGL_CORE_PROFILE` will
	cause @ref glfwCreateWindow to fail.

	Also, on Mac OS X 10.6 and below, the `GLFW_CONTEXT_VERSION_MAJOR` and
	`GLFW_CONTEXT_VERSION_MINOR` hints will fail if given a version above 2.1, the
	`GLFW_OPENGL_DEBUG_CONTEXT` hint will have no effect, and setting the
	`GLFW_OPENGL_PROFILE` or `GLFW_OPENGL_FORWARD_COMPAT` hints to a non-zero value
	will cause @ref glfwCreateWindow to fail.

	*/