Makes the context of the specified window current for the calling thread.
This function makes the OpenGL or OpenGL ES context of the specified window current on the calling thread. A context must only be made current on a single thread at a time and each thread can have only a single current context at a time.
When moving a context between threads, you must make it non-current on the old thread before making it current on the new one.
By default, making a context non-current implicitly forces a pipeline flush.
On machines that support
GL_KHR_context_flush_control, you can control
whether a context performs this flush by setting the
The specified window must have an OpenGL or OpenGL ES context. Specifying
a window without a context will generate a
$windowThe window whose context to make current, or
NULLto detach the current context.