GLXDrawable _d_r_a_w_a_b_l_e )
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ggllXXSSwwaappBBuuffffeerrss performs an implicit ggllFFlluusshh before it returns. Subsequent OpenGL commands may be issued immediately after calling ggllXXSSwwaappBBuuffffeerrss, but are not executed until the buffer exchange is completed.
If _d_r_a_w_a_b_l_e was not created with respect to a double-buffered visual, ggllXXSSwwaappBBuuffffeerrss has no effect, and no error is generated.
All GLX rendering contexts share the same notion of which are front buffers and which are back buffers. One consequence is that when multiple clients are rendering to the same double-buffered window, all of them should finish rendering before one of them issues the command to swap buffers. The clients are responsible for implementing this synchronization. Typically this is accomplished by executing ggllFFiinniisshh and then using a semaphore in shared memory to rendezvous before swapping.
GGLLXXBBaaddCCuurrrreennttWWiinnddooww is generated if _d_p_y and _d_r_a_w_a_b_l_e are respectively the display and drawable associated with the current context of the calling thread, and _d_r_a_w_a_b_l_e identifies a window that is no longer valid.