Prevent crash when AFT draws an AFT

by remember the previous render target.

src/RageDisplay.h

@@ -244,6 +244,8 @@ public:
 	 */
 	virtual unsigned CreateRenderTarget( const RenderTargetParam &, int & /* iTextureWidthOut */, int & /* iTextureHeightOut */ ) { return 0; }
 
+	virtual unsigned GetRenderTarget()	{ return 0; }
+
 	/* Set the render target, or 0 to resume rendering to the framebuffer. An active render
 	 * target may not be used as a texture. If bPreserveTexture is true, the contents
 	 * of the texture will be preserved from the previous call; otherwise, cleared.  If

src/RageDisplay_OGL.cpp

@@ -2475,6 +2475,14 @@ unsigned RageDisplay_Legacy::CreateRenderTarget( const RenderTargetParam &param,
 	return iTexture;
 }
 
+unsigned RageDisplay_Legacy::GetRenderTarget( )
+{
+	for( map<unsigned, RenderTarget*>::const_iterator it = g_mapRenderTargets.begin( ); it != g_mapRenderTargets.end( ); ++it )
+	if( it->second == g_pCurrentRenderTarget )
+		return it->first;
+	return 0;
+}
+
 void RageDisplay_Legacy::SetRenderTarget( unsigned iTexture, bool bPreserveTexture )
 {
 	if (iTexture == 0)

src/RageDisplay_OGL.h

@@ -71,6 +71,7 @@ public:
 	bool IsEffectModeSupported( EffectMode effect );
 	bool SupportsRenderToTexture() const;
 	unsigned CreateRenderTarget( const RenderTargetParam &param, int &iTextureWidthOut, int &iTextureHeightOut );
+	unsigned GetRenderTarget();
 	void SetRenderTarget( unsigned iHandle, bool bPreserveTexture );
 	bool IsZWriteEnabled() const;
 	bool IsZTestEnabled() const;

src/RageTextureRenderTarget.cpp

@@ -47,6 +47,7 @@ void RageTextureRenderTarget::Destroy()
 
 void RageTextureRenderTarget::BeginRenderingTo( bool bPreserveTexture )
 {
+	m_iPreviousRenderTarget = DISPLAY->GetRenderTarget( );
 	DISPLAY->SetRenderTarget( m_iTexHandle, bPreserveTexture );
 
 	/* We're rendering to a texture, not the framebuffer.
@@ -69,7 +70,7 @@ void RageTextureRenderTarget::FinishRenderingTo()
 	DISPLAY->CameraPopMatrix();
 	DISPLAY->PopMatrix();
 
-	DISPLAY->SetRenderTarget( 0 );
+	DISPLAY->SetRenderTarget( m_iPreviousRenderTarget );
 }
 
 // lua start

src/RageTextureRenderTarget.h

@@ -27,6 +27,7 @@ private:
 	void Create();
 	void Destroy();
 	unsigned m_iTexHandle;
+	unsigned m_iPreviousRenderTarget;
 };
 
 #endif