add an overload which is called from the main thread, just before using the concurrent rendering thread

stepmania/src/RageDisplay.h

@@ -159,6 +159,8 @@ public:
 
 	// If threaded rendering is supported, these will be called from the rendering
 	// thread before and after rendering.
+	virtual void BeginConcurrentRenderingMainThread() { }
+	virtual void EndConcurrentRenderingMainThread() { }
 	virtual void BeginConcurrentRendering() { }
 	virtual void EndConcurrentRendering() { }
 

stepmania/src/RageDisplay_OGL.cpp

@@ -1615,6 +1615,16 @@ bool RageDisplay_OGL::SupportsThreadedRendering()
 	return g_pWind->SupportsThreadedRendering();
 }
 
+void RageDisplay_OGL::BeginConcurrentRenderingMainThread()
+{
+	g_pWind->BeginConcurrentRenderingMainThread();
+}
+
+void RageDisplay_OGL::EndConcurrentRenderingMainThread()
+{
+	g_pWind->EndConcurrentRenderingMainThread();
+}
+
 void RageDisplay_OGL::BeginConcurrentRendering()
 {
 	g_pWind->BeginConcurrentRendering();

stepmania/src/RageDisplay_OGL.h

@@ -16,6 +16,8 @@ public:
 	const PixelFormatDesc *GetPixelFormatDesc(PixelFormat pf) const;
 
 	bool SupportsThreadedRendering();
+	void BeginConcurrentRenderingMainThread();
+	void EndConcurrentRenderingMainThread();
 	void BeginConcurrentRendering();
 	void EndConcurrentRendering();
 

stepmania/src/arch/LowLevelWindow/LowLevelWindow.h

@@ -27,6 +27,8 @@ public:
 	virtual const VideoModeParams &GetActualVideoModeParams() const = 0;
 
 	virtual bool SupportsThreadedRendering() { return false; }
+	virtual void BeginConcurrentRenderingMainThread() { }
+	virtual void EndConcurrentRenderingMainThread() { }
 	virtual void BeginConcurrentRendering() { }
 	virtual void EndConcurrentRendering() { }
 };