Make RageDisplay_OGL::GetOrthoMatrix the default implementation.

stepmania/src/RageDisplay.cpp

@@ -604,6 +604,19 @@ RageDisplay::PixelFormat RageDisplay::FindPixelFormat(
 	return NUM_PIX_FORMATS;
 }
 	
+/* These convert to OpenGL's coordinate system: -1,-1 is the bottom-left, +1,+1 is the
+ * top-right, and Z goes from -1 (viewer) to +1 (distance).  It's a little odd, but
+ * very well-defined. */
+RageMatrix RageDisplay::GetOrthoMatrix( float l, float r, float b, float t, float zn, float zf )
+{
+	RageMatrix m(
+		2/(r-l),      0,            0,           0,
+		0,            2/(t-b),      0,           0,
+		0,            0,            -2/(zf-zn),   0,
+		-(r+l)/(r-l), -(t+b)/(t-b), -(zf+zn)/(zf-zn),  1 );
+	return m;
+}
+
 RageMatrix RageDisplay::GetFrustumMatrix( float l, float r, float b, float t, float zn, float zf )
 {
 	// glFrustrum

stepmania/src/RageDisplay.h

@@ -314,7 +314,7 @@ protected:
 	RageMatrix GetPerspectiveMatrix(float fovy, float aspect, float zNear, float zFar);
 
 	// Different for D3D and OpenGL.  Not sure why they're not compatible. -Chris
-	virtual RageMatrix GetOrthoMatrix( float l, float r, float b, float t, float zn, float zf ) = 0; 
+	virtual RageMatrix GetOrthoMatrix( float l, float r, float b, float t, float zn, float zf ); 
 	virtual RageMatrix GetFrustumMatrix( float l, float r, float b, float t, float zn, float zf ); 
 
 	//

stepmania/src/RageDisplay_OGL.cpp

@@ -1820,16 +1820,6 @@ void RageDisplay_OGL::SetAlphaTest( bool b )
 		glDisable( GL_ALPHA_TEST );
 }
 
-RageMatrix RageDisplay_OGL::GetOrthoMatrix( float l, float r, float b, float t, float zn, float zf )
-{
-	RageMatrix m(
-		2/(r-l),      0,            0,           0,
-		0,            2/(t-b),      0,           0,
-		0,            0,            -2/(zf-zn),   0,
-		-(r+l)/(r-l), -(t+b)/(t-b), -(zf+zn)/(zf-zn),  1 );
-	return m;
-}
-
 
 /*
  * Although we pair texture formats (eg. GL_RGB8) and surface formats

stepmania/src/RageDisplay_OGL.h

@@ -83,7 +83,6 @@ protected:
 	CString TryVideoMode( VideoModeParams params, bool &bNewDeviceOut );
 	RageSurface* CreateScreenshot();
 	void SetViewport(int shift_left, int shift_down);
-	RageMatrix GetOrthoMatrix( float l, float r, float b, float t, float zn, float zf ); 
 	PixelFormat GetImgPixelFormat( RageSurface* &img, bool &FreeImg, int width, int height, bool bPalettedTexture );
 	bool SupportsSurfaceFormat( PixelFormat pixfmt );