NAME
glXCreateContext - create a new GLX rendering context
C SPECIFICATION
GLXContext glXCreateContext( Display *dpy,
XVisualInfo *vis,
GLXContext shareList,
Bool direct )
PARAMETERS
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).
DESCRIPTION
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.
NOTES
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.
ERRORS
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.
SEE ALSO
glXDestroyContext, glXGetConfig, glXIsDirect, glXMakeCurrent