glXCreateContext(3G)	    OpenGL Reference - GLX	  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	and
		texture	objects.  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 and the connection is to an X
     server that is local.  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 cannot be used to render to GLX pixmaps.

     If	shareList is not NULL, then all	display-list and texture object
     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 and texture object space as long as they 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



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glXCreateContext(3G)	    OpenGL Reference - GLX	  glXCreateContext(3G)



     rendering contexts	to share an address space.


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.


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	(e.g., if the 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




















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