DeltaTime.cpp

#include "DeltaTime.hpp"

Timer::Time Timer::s_MainTimer = Timer::Time();

DeltaTime.hpp

// DeltaTime.h
#pragma once

#ifndef __DELTA_TIME_H__
#define __DELTA_TIME_H__

#include "profileapi.h"

// static class
class Timer final
{
private:
  class Time
  {
    // friend로 Timer에게만 공개합니다.
    friend Timer;
  private:
    Time()
    {
      reset();
    }
    
    ~Time() = default;

    void reset( )
    {
      QueryPerformanceFrequency(&m_CountTime);
      QueryPerformanceCounter(&m_CurTime);
      QueryPerformanceCounter(&m_PrevTime);
    }
  
    float update( )
    {
      QueryPerformanceCounter(&m_CurTime);
    
      // delta time = current time - previous time
      m_dDeltaTime = ( static_cast<double>(m_CurTime.QuadPart) - static_cast<double>(m_PrevTime.QuadPart) ) / static_cast<double>(m_CountTime.QuadPart);

      m_fDeltaTime = static_cast<float>(m_dDeltaTime);
      m_PrevTime = m_CurTime;
    
      return m_fDeltaTime;
    }

    private:
      LARGE_INTEGER m_CountTime;
      LARGE_INTEGER m_CurTime;
      LARGE_INTEGER m_PrevTime;
      double m_dDeltaTime;
      float m_fDeltaTime;
    };

private:
  static Time s_MainTimer;

public:
  Timer() = delete;
  ~Timer() = delete;

  static float DeltaTime()
  {
    return s_MainTimer.m_fDeltaTime;
  }

  static void Update()
  {
    s_MainTimer.update();
  }

  static void Reset()
  {
    s_MainTimer.reset();
  }
};

#endif // !__DELTA_TIME_H__