timer.h

game programing code

//==============================================================
//==============================================================
//= timer.h ====================================================
//= Original coders: Trent Polack ([e-mail])		   =
//==============================================================
//= The code routines for a timer system, including an FPS     =
//= counter.												   =
//==============================================================
//==============================================================
#ifndef __TIMER_H__
#define __TIMER_H__


//--------------------------------------------------------------
//--------------------------------------------------------------
//- HEADERS AND LIBRARIES --------------------------------------
//--------------------------------------------------------------
//--------------------------------------------------------------
#include <windows.h>
#include <stdio.h>
#include <math.h>


//--------------------------------------------------------------
//--------------------------------------------------------------
//- CLASS ------------------------------------------------------
//--------------------------------------------------------------
//--------------------------------------------------------------
class CTIMER
{
	private:
		//performance timer variables
		__int64       m_i64PerformanceTimerStart;
		__int64       m_i64PerformanceTimerElapsed;

		//multimedia timer variables
		unsigned long m_ulMMTimerElapsed;
		unsigned long m_ulMMTimerStart;

		//general timer variables
		__int64		  m_i64Frequency;
		float		  m_fResolution;
		bool		  m_bPerformanceTimer;

		//FPS variables
		float m_fTime1;
		float m_fTime2;
		float m_fDiffTime;
		float m_fFPS;
		int m_iFramesElapsed;

	public:


	//----------------------------------------------------------
	// Name:			CTIMER::Init - public
	// Description:		Initiate the timer for the program
	// Arguments:		None
	// Return Value:	A boolean variable: -true: using performance timer
	//										-false: using multimedia timer
	//----------------------------------------------------------
	bool Init( void )
	{
		//check to see if we are going to be using the performance counter
		if( QueryPerformanceFrequency( ( LARGE_INTEGER* )&m_i64Frequency ) )
		{
			//we are able to use the performance timer
			m_bPerformanceTimer= true;

			//get the current time and store it in m_i64PerformanceTimerStart
			QueryPerformanceCounter( ( LARGE_INTEGER* )&m_i64PerformanceTimerStart );
			
			//calculate the timer resolution
			m_fResolution= ( float )( ( ( double )1.0f )/( ( double )m_i64Frequency ) );
			
			//initialize the elapsed time variable
			m_i64PerformanceTimerElapsed= m_i64PerformanceTimerStart;
		}

		//we cannot use the performence counter, so we'll use the multimedia counter
		else
		{
			//we're using the multimedia counter
			m_bPerformanceTimer= false;

			m_ulMMTimerStart   = timeGetTime( );	//record the time the program started
			m_ulMMTimerElapsed = m_ulMMTimerStart;	//initialize the elapsed time variable
			m_fResolution	   = 1.0f/1000.0f;
			m_i64Frequency     = 1000;
		}

		return m_bPerformanceTimer;
	}

	//----------------------------------------------------------
	// Name:			CTIMER::Update - public
	// Description:		Update the timer (perform FPS counter calculations)
	// Arguments:		None
	// Return Value:	None
	//----------------------------------------------------------
	void Update( void )
	{
		//increase the number of frames that have passed
		m_iFramesElapsed++;

		if( m_iFramesElapsed%5==1 )
		  m_fTime1 = GetTime( )/1000;

		else if( m_iFramesElapsed%5==0 ) 
		{
			m_fTime2   = GetTime( )/1000;
			m_fDiffTime= ( float )fabs( m_fTime2-m_fTime1 );      
		}  

		m_fFPS= 5/( m_fDiffTime );
	}

	//----------------------------------------------------------
	// Name:			CTIMER::GetTime - public
	// Description:		Get the current time since the program started
	// Arguments:		None
	// Return Value:	A floating-point variable: The time elapsed since
	//					the program started.
	//----------------------------------------------------------
	float GetTime( void )
	{
		 __int64 i64Time;

		//check to see if we are using the performance counter
		if( m_bPerformanceTimer )
		{
			//get the current performance time
			QueryPerformanceCounter( ( LARGE_INTEGER* )&i64Time );

			//return the time since the program started
			return ( ( float )( i64Time - m_i64PerformanceTimerStart )*m_fResolution )*1000.0f;
		}

		//we are using the multimedia counter
		else
		{
			//return the time since the program started
			return ( ( float )( timeGetTime( ) - m_ulMMTimerStart )*m_fResolution )*1000.0f;
		}
	}

	//----------------------------------------------------------
	// Name:			CTIMER::GetFPS - public
	// Description:		Get the current number of frames per second
	// Arguments:		None
	// Return Value:	A floating-point variables: the number of
	//					frames per second
	//----------------------------------------------------------
	inline float GetFPS( void )
	{	return m_fFPS;	}

	CTIMER( void )
	{	}
	~CTIMER( void )
	{	}
};


#endif	//__TIMER_H__