glXCreateContext() glXCreateContext()
glXCreateContext - create a new GLX rendering context
GLXContext glXCreateContext(
Display *dpy,
XVisualInfo *vis,
GLXContext shareList,
Bool direct );
Specifies the connection to the X server. Specifies the
visual that defines the frame buffer resources available
to the rendering context. It is a pointer to an XVisualInfo
structure, not a visual ID or a pointer to a Visual.
Specifies the context with which to share display lists.
NULL indicates that no sharing is to take place. Specifies
whether rendering is to be done with a direct connection
to the graphics system if possible (True) or through
the X server (False).
glXCreateContext() creates a GLX rendering context and
returns its handle. This context can be used to render
into both windows and GLX pixmaps. If glXCreateContext()
fails to create a rendering context, NULL is returned.
If direct is True, then a direct rendering context is created
if the implementation supports direct rendering, if
the connection is to an X server that is local, and if a
direct rendering context is available. (An implementation
may return an indirect context when direct is True). If
direct is False, then a rendering context that renders
through the X server is always created. Direct rendering
provides a performance advantage in some implementations.
However, direct rendering contexts cannot be shared outside
a single process, and they may be unable to render to
GLX pixmaps.
If shareList is not NULL, then all display-list indexes
and definitions are shared by context shareList and by the
newly created context. An arbitrary number of contexts can
share a single display-list space. However, all rendering
contexts that share a single display-list space must themselves
exist in the same address space. Two rendering contexts
share an address space if both are nondirect using
the same server, or if both are direct and owned by a single
process. Note that in the nondirect case, it is not
necessary for the calling threads to share an address
space, only for their related rendering contexts to share
an address space.
If the GL version is 1.1 or greater, then all texture
objects except object 0, are shared by any contexts that
share display lists.
XVisualInfo is defined in Xutil.h. It is a structure that
includes visual, visualID, screen, and depth elements.
A process is a single execution environment, implemented
in a single address space, consisting of one or more
threads.
A thread is one of a set of subprocesses that share a single
address space, but maintain separate program counters,
stack spaces, and other related global data. A thread that
is the only member of its subprocess group is equivalent
to a process.
It may not be possible to render to a GLX pixmap with a
direct rendering context.
NULL is returned if execution fails on the client side.
BadMatch is generated if the context to be created would
not share the address space or the screen of the context
specified by shareList.
BadValue is generated if vis is not a valid visual (for
example, if a particular GLX implementation does not support
it).
GLXBadContext is generated if shareList is not a GLX context
and is not NULL.
BadAlloc is generated if the server does not have enough
resources to allocate the new context.
glXDestroyContext(3), glXGetConfig(3), glXIsDirect(3),
glXMakeCurrent(3)
glXCreateContext()
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