F.P.S. Counter

    
//==============================================================

//= Timer.h

//= Original coder: Trent Polack (trent@codershq.com)

//==============================================================

//= A simple and effective timing class

//==============================================================

#ifndef __DEMOFRAMEWORK_TIMER_H__
#define __DEMOFRAMEWORK_TIMER_H__

#include <windows.h>
#include <stdio.h>
#include <math.h>

namespace DemoFramework {
	//a dual-purpose timer class (performance and multimedia timer support)

	class Timer {
		//performance timer variables

		__int64 m_perfTimerStart;
		__int64 m_perfTimerElapsed;

		//multimedia timer variables

		unsigned long m_mmTimerElapsed;
		unsigned long m_mmTimerStart;

		//general timer variables

		__int64	m_frequency;
		float m_resolution;
		bool m_usePerfTimer;

		//FPS variables

		float m_time1;
		float m_time2;
		float m_diffTime;
		float m_FPS;
		int m_framesElapsed;

	public:

		//initialize the timer system

		bool Create( void ) {
			//check to see if we are going to be using the performance counter

			if( QueryPerformanceFrequency( ( LARGE_INTEGER * )&m_frequency ) ) {
				//we are able to use the performance timer

				m_usePerfTimer= true;

				//get the current time and store it in m_perfTimerStart

				QueryPerformanceCounter( ( LARGE_INTEGER * )&m_perfTimerStart );
				
				//calculate the timer resolution

				m_resolution= ( float )( ( ( double )1.0f )/( ( double )m_frequency ) );
				
				//initialize the elapsed time variable

				m_perfTimerElapsed= m_perfTimerStart;
			} else {
				//we cannot use the performance counter, so we'll use the multimedia counter

				m_usePerfTimer= false;

				m_mmTimerStart= timeGetTime( );		//record the time the program started

				m_mmTimerElapsed= m_mmTimerStart;	//initialize the elapsed time variable

				m_resolution= 1.0f/1000.0f;
				m_frequency= 1000;
			}

			return m_usePerfTimer;
		}

		//update the timer system

		void Update( void ) {
			//increase the number of frames that have passed

			m_framesElapsed++;

			if( ( m_framesElapsed % 5 ) == 1 ) m_time1= GetTime( )/1000;

			else if( ( m_framesElapsed % 5 ) == 0 ) {
				m_time2   = GetTime( )/1000;
				m_diffTime= ( float )fabs( m_time2 - m_time1 );      
			}  

			m_FPS= 5/( m_diffTime );
		}

		//get the elapsed program time

		float GetTime( void ) {
			 __int64 time;

			//check to see if we are using the performance counter

			if( m_usePerfTimer ) {
				//get the current performance time

				QueryPerformanceCounter( ( LARGE_INTEGER * )&time );

				//return the time since the program started

				return ( ( float )( time - m_perfTimerStart )*m_resolution )*1000.0f;
			} else {
				//return the time since the program started

				return ( ( float )( timeGetTime( ) - m_mmTimerStart )*m_resolution )*1000.0f;
			}
		}

		//get the current number of frames per second

		inline float GetFPS( void ) { return m_FPS; }

	Timer( void ) { }
	~Timer( void ) { }
	};
}


#endif	//__DEMOFRAMEWORK_TIMER_H__