glXCreateContext(3G)

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