add concurrent rendering hooks

stepmania/src/RageDisplay.h

@@ -157,6 +157,11 @@ public:
 	virtual bool SupportsThreadedRendering() { return false; }
 	virtual bool SupportsPerVertexMatrixScale() = 0;
 
+	// If threaded rendering is supported, these will be called from the rendering
+	// thread before and after rendering.
+	virtual void BeginConcurrentRendering() { }
+	virtual void EndConcurrentRendering() { }
+
 	/* return 0 if failed or internal texture resource handle 
 	 * (unsigned in OpenGL, texture pointer in D3D) */
 	virtual unsigned CreateTexture( 

stepmania/src/RageDisplay_OGL.cpp

@@ -1606,6 +1606,21 @@ const RageDisplay::PixelFormatDesc *RageDisplay_OGL::GetPixelFormatDesc(PixelFor
 	return &PIXEL_FORMAT_DESC[pf];
 }
 
+bool RageDisplay_OGL::SupportsThreadedRendering()
+{
+	return g_pWind->SupportsThreadedRendering();
+}
+
+void RageDisplay_OGL::BeginConcurrentRendering()
+{
+	g_pWind->BeginConcurrentRendering();
+}
+
+void RageDisplay_OGL::EndConcurrentRendering()
+{
+	g_pWind->EndConcurrentRendering();
+}
+
 void RageDisplay_OGL::DeleteTexture( unsigned uTexHandle )
 {
 	unsigned int uTexID = uTexHandle;

stepmania/src/RageDisplay_OGL.h

@@ -15,6 +15,10 @@ public:
 	void ResolutionChanged();
 	const PixelFormatDesc *GetPixelFormatDesc(PixelFormat pf) const;
 
+	bool SupportsThreadedRendering();
+	void BeginConcurrentRendering();
+	void EndConcurrentRendering();
+
 	bool BeginFrame();	
 	void EndFrame();
 	VideoModeParams GetActualVideoModeParams() const;

stepmania/src/arch/LowLevelWindow/LowLevelWindow.h

@@ -25,6 +25,10 @@ public:
 	virtual void Update() { }
 
 	virtual VideoModeParams GetActualVideoModeParams() const = 0;
+
+	virtual bool SupportsThreadedRendering() { return false; }
+	virtual void BeginConcurrentRendering() { }
+	virtual void EndConcurrentRendering() { }
 };
 
 #endif