text: #include "CTimer.h"
  
  //---------------------- default constructor ------------------------------
  //
  //-------------------------------------------------------------------------
  
  CTimer::CTimer(): m_FPS(0),
  				          m_TimeElapsed(0.0f),
  				          m_FrameTime(0),
  				          m_LastTime(0),
  				          m_PerfCountFreq(0)
  {
  	//how many ticks per sec do we get
  	QueryPerformanceFrequency( (LARGE_INTEGER*) &m_PerfCountFreq);
  	
  	m_TimeScale = 1.0f/m_PerfCountFreq;
  }
  
  //---------------------- constructor -------------------------------------
  //
  //	use to specify FPS
  //
  //-------------------------------------------------------------------------
  
  CTimer::CTimer(float fps): m_FPS(fps),
  						               m_TimeElapsed(0.0f),
  						               m_LastTime(0),
  						               m_PerfCountFreq(0)
  {
  
  	//how many ticks per sec do we get
  	QueryPerformanceFrequency( (LARGE_INTEGER*) &m_PerfCountFreq);
  
  	m_TimeScale = 1.0f/m_PerfCountFreq;
  
  	//calculate ticks per frame
  	m_FrameTime = (LONGLONG)(m_PerfCountFreq / m_FPS);
  }
  
  
  //------------------------Start()-----------------------------------------
  //
  //	call this immediately prior to game loop. Starts the timer (obviously!)
  //
  //--------------------------------------------------------------------------
  void CTimer::Start()
  {
  	//get the time
  	QueryPerformanceCounter( (LARGE_INTEGER*) &m_LastTime);
  
  	//update time to render next frame
  	m_NextTime = m_LastTime + m_FrameTime;
  
  	return;
  }
  
  //-------------------------ReadyForNextFrame()-------------------------------
  //
  //	returns true if it is time to move on to the next frame step. To be used if
  //	FPS is set.
  //
  //----------------------------------------------------------------------------
  bool CTimer::ReadyForNextFrame()
  {
  	if (!m_FPS)
    {
      MessageBox(NULL, "No FPS set in timer", "Doh!", 0);
  
      return false;
    }
    
    QueryPerformanceCounter( (LARGE_INTEGER*) &m_CurrentTime);
  
  	if (m_CurrentTime > m_NextTime)
  	{
  
  		m_TimeElapsed	= (m_CurrentTime - m_LastTime) * m_TimeScale;
  		m_LastTime		= m_CurrentTime;
  
  		//update time to render next frame
  		m_NextTime = m_CurrentTime + m_FrameTime;
  
  		return true;
  	}
  
  	return false;
  }
  
  //--------------------------- TimeElapsed --------------------------------
  //
  //	returns time elapsed since last call to this function. Use in main
  //	when calculations are to be based on dt.
  //
  //-------------------------------------------------------------------------
  double CTimer::TimeElapsed()
  {
  	QueryPerformanceCounter( (LARGE_INTEGER*) &m_CurrentTime);
  	
  	m_TimeElapsed	= (m_CurrentTime - m_LastTime) * m_TimeScale;
  	
  	m_LastTime		= m_CurrentTime;
  
  	return m_TimeElapsed;
  		
  }
  