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-rw-r--r--xorg-server/dix/dixutils.c25
1 files changed, 25 insertions, 0 deletions
diff --git a/xorg-server/dix/dixutils.c b/xorg-server/dix/dixutils.c
index 5de74c8b4..cdd370bd6 100644
--- a/xorg-server/dix/dixutils.c
+++ b/xorg-server/dix/dixutils.c
@@ -866,3 +866,28 @@ InitCallbackManager(void)
{
DeleteCallbackManager();
}
+
+/**
+ * Coordinates the global GL context used by modules in the X Server
+ * doing rendering with OpenGL.
+ *
+ * When setting a GL context (glXMakeCurrent() or eglMakeCurrent()),
+ * there is an expensive implied glFlush() required by the GLX and EGL
+ * APIs, so modules don't want to have to do it on every request. But
+ * the individual modules using GL also don't know about each other,
+ * so they have to coordinate who owns the current context.
+ *
+ * When you're about to do a MakeCurrent, you should set this variable
+ * to your context's address, and you can skip MakeCurrent if it's
+ * already set to yours.
+ *
+ * When you're about to do a DestroyContext, you should set this to
+ * NULL if it's set to your context.
+ *
+ * When you're about to do an unbindContext on a DRI driver, you
+ * should set this to NULL. Despite the unbindContext interface
+ * sounding like it only unbinds the passed in context, it actually
+ * unconditionally clears the dispatch table even if the given
+ * context wasn't current.
+ */
+void *lastGLContext = NULL;