VCRA-SZCZERBACKI-PointBasedRendering/timer.cpp

#include "timer.h"
#include <windows.h>

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

static FARPROC timeGetTimeImp = NULL;
static HMODULE libraryInstance = NULL;

SS::UINT32      Timer::m_startTime = 0;
SS::UINT32      Timer::m_currentTime = 0;
int             Timer::m_referenceCount = 0;

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

Timer::Timer( )
{
        if( m_referenceCount++ == 0 )
        {
                libraryInstance = LoadLibrary("WINMM.DLL");
                if( !libraryInstance ) svError("couldn't load WINMM.DLL");
                timeGetTimeImp = GetProcAddress(libraryInstance,"timeGetTime");
                if( !timeGetTimeImp ) svError("couldn't find function timeGetTime from WINMM.DLL");

                m_startTime  = timeGetTimeImp();
                m_currentTime = m_startTime;
        }

        m_initialAge = getAge( );
        m_newAge = 0.0f;
        m_prevAge = 0.0f;
}

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

Timer::~Timer( )
{
        if( --m_referenceCount == 0 )
        {
                if( libraryInstance ) FreeLibrary(libraryInstance);
                libraryInstance = NULL;
        }
}

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

float Timer::getAge( )
{
        m_currentTime = timeGetTimeImp( );
        return float( m_currentTime - m_startTime ) / 1000.0f;
}

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

// calculate delta from last call to sample
float Timer::sample( )
{
        m_prevAge = m_newAge;
        m_newAge = getAge( ) - m_initialAge;
        return m_newAge - m_prevAge;
}

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

// get the difference between the last two sample calls
float Timer::getDelta( ) const
{
        return m_newAge - m_prevAge;
}

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

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