glXCreateContext - create a new GLX rendering context
GLXContext glXCreateContext( Display *dpy,
Bool direct )
dpy Specifies the connection to the X server.
vis 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.
shareList Specifies the context with which to share display lists. NULL indicates that
no sharing is to take place.
direct 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 sup-
ports 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 con-
text 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 con-
texts 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 neces-
sary 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, con-
sisting 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
glXDestroyContext, glXGetConfig, glXIsDirect, glXMakeCurrent