const int GAME_UPDATES_PER_SECOND = 50; // desired game speed in hz
        const float PIC_SPEED_PIXELS_PER_UPDATE = 4.0f;
        const int TICKS_TO_WAIT_FOR_NEXT_GAME_UPDATE = 1000 / GAME_UPDATES_PER_SECOND;
        const int MIN_FPS_LIMIT = 5;
        const int MAX_FRAMESKIP = GAME_UPDATES_PER_SECOND / MIN_FPS_LIMIT;

	float fInterpolation;
	float fDelta = 1.0f; // not needed in this game loop implementation
	int iNextUpdateTick = SDL_GetTicks();
	int iCurrentFPSTick;
	int iPreviousFPSTick = iNextUpdateTick;
	int iElapsedFPSTicks;
	int iElapsedUpdateTicks;
	int iPreviousUpdateTick = iPreviousFPSTick;
	int iCurrentUpdateTick;
	int iLoops;

	g_fFrameRate = 0.0f;
	g_fUpdateRate = 0.0f;

	while( !g_bQuit && !g_bSpace ) {

		// reset update loops counter
		iLoops = 0;

		// perform update (maybe more than once on slow hardware)
		while( SDL_GetTicks() > iNextUpdateTick && iLoops < MAX_FRAMESKIP ) {

			// update game state
			update( PIC_SPEED_PIXELS_PER_UPDATE, fDelta );

			// work out the update rate
			iCurrentUpdateTick = SDL_GetTicks();
			iElapsedUpdateTicks = iCurrentUpdateTick - iPreviousUpdateTick;
			g_fUpdateRate = 1000.0f / static_cast<float>( iElapsedUpdateTicks );
			iPreviousUpdateTick = iCurrentUpdateTick;	

			// is it time for another update?
			iNextUpdateTick += TICKS_TO_WAIT_FOR_NEXT_GAME_UPDATE;
			iLoops++;
		}

		// get the interpolation value for the rendering
		fInterpolation = static_cast<float>( SDL_GetTicks() + TICKS_TO_WAIT_FOR_NEXT_GAME_UPDATE - iNextUpdateTick ) 
					   / static_cast<float>( TICKS_TO_WAIT_FOR_NEXT_GAME_UPDATE );

		// render as fast as possible with interpolation
		render( fInterpolation );

		// work out the frame rate from the elapsed ticks
		iCurrentFPSTick = SDL_GetTicks();
		iElapsedFPSTicks = iCurrentFPSTick - iPreviousFPSTick;
		g_fFrameRate = 1000.0f / static_cast<float>( iElapsedFPSTicks );
		iPreviousFPSTick = iCurrentFPSTick;
	}