GLXCREATECONTEXT(3)GLXCREATECONTEXT(3)NAMEglXCreateContext - create a new GLX rendering context
C SPECIFICATION
GLXContext glXCreateContext( Display *dpy,
XVisualInfo *vis,
GLXContext shareList,
Bool direct )
delim $$
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).
DESCRIPTIONglXCreateContext 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
March 1, 2011
