glXCopyContext.3G man page
glXCopyContext — copy state from one rendering context to another
void glXCopyContext(Display * dpy, GLXContext src, GLXContext dst, unsigned long mask);
Specifies the connection to the X server.
Specifies the source context.
Specifies the destination context.
Specifies which portions of src state are to be copied to dst.
glXCopyContext copies selected groups of state variables from src to dst. mask indicates which groups of state variables are to be copied. mask contains the bitwise OR of the same symbolic names that are passed to the GL command glPushAttrib(). The single symbolic constant GLX_ALL_ATTRIB_BITS can be used to copy the maximum possible portion of rendering state.
The copy can be done only if the renderers named by src and dst share an 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.
Not all values for GL state can be copied. For example, pixel pack and unpack state, render mode state, and select and feedback state are not copied. The state that can be copied is exactly the state that is manipulated by the GL command glPushAttrib().
An implicit glFlush() is done by glXCopyContext if src is the current context for the calling thread.
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.
BadMatch is generated if rendering contexts src and dst do not share an address space or were not created with respect to the same screen.
BadAccess is generated if dst is current to any thread (including the calling thread) at the time glXCopyContext is called.
GLXBadCurrentWindow is generated if src is the current context and the current drawable is a window that is no longer valid.
GLXBadContext is generated if either src or dst is not a valid GLX context.
glPushAttrib(), glXCreateContext(), glXIsDirect()
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