if(drawmode!=motionblurmode||mainmenu){
#ifdef WIN32
if(drawmode!=motionblurmode) SwapBuffers( hDC);
-#else
+#elif PLATFORM_MACOSX
if(drawmode!=motionblurmode)aglSwapBuffers(gaglContext); // send swap command
+#elif USE_SDL
+ if(drawmode!=motionblurmode)SDL_GL_SwapBuffers();
+#else
+ #error define your platform.
#endif // send swap command
}