opengl如何把glutIdleFunc的帧数调低，感觉转动时速度太快，可以不调角度来让旋转变慢么？

Posted 2023-04-23

参考技术A 你可以试试调用Windows的多媒体时钟，可以获得Windows时间。也就是说如果你把系统的1s“延长”，旋转就可以变慢。可能不太好，我只是猜想

如何在 OpenGL 中捕获准确的帧速率

【中文标题】如何在 OpenGL 中捕获准确的帧速率

【英文标题】：How to capture accurate framerate in OpenGL

【发布时间】：2010-01-29 05:23:53

【问题描述】：

在原生 windows opengl c++ 中获得准确帧率（每秒帧数）的好方法是什么？

【问题讨论】：

您可能希望切换到每帧毫秒数：mvps.org/directx/articles/fps_versus_frame_time.htm

【参考方案1】：

这是我以前在 ATL 项目中使用的计时器类。有一段时间没玩过C++或者opengl了，不过也许这会给你一些想法：

用法

// Put this in your class somewhere
CTimer m_timer;

// Initialize the timer using
m_timer.Init();

// Call this everytime you call draw your scene
m_timer.Update();

// Call this to get the frames/sec
m_timer.GetFPS();

定时器类

// Timer.h: Timer class used for determining elapsed time and 
//              frames per second.
//
//////////////////////////////////////////////////////////////////////

#ifndef _E_TIMER_H
#define _E_TIMER_H

#pragma once

//////////////////////////////////////////////////////////////////////
// INCLUDES
//////////////////////////////////////////////////////////////////////

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

//////////////////////////////////////////////////////////////////////
// CLASSES
//////////////////////////////////////////////////////////////////////

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::CTimer
    // Desc:    Default constructor
    // Args:    None
    // Rets:    None
    //----------------------------------------------------------
    CTimer( void )
        : m_fFPS(0.0f), m_fTime1(0.0f), m_fTime2(0.0f), m_fDiffTime(0.0f), m_iFramesElapsed(0)
       

    //----------------------------------------------------------
    // Name:    CTimer::CTimer
    // Desc:    Default destructor
    // Args:    None
    // Rets:    None
    //----------------------------------------------------------
    virtual ~CTimer( void )
       

    //----------------------------------------------------------
    // Name:    CTimer::Init - public
    // Desc:    Initiate the timer for the program
    // Args:    None
    // Rets:    bool:   -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
    // Desc:    Update the timer (perform FPS counter calculations)
    // Args:    None
    // Rets:    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_fTime1 = m_fTime2;
            m_fTime2   = GetTime( )/1000;
            m_fDiffTime= ( float )fabs( m_fTime2-m_fTime1 );      
          

        m_fFPS= 5/( m_fDiffTime );



        /*m_fTime2   = GetTime( )/1000;
        m_fDiffTime= ( float )fabs( m_fTime2-m_fTime1 );
        if (m_fDiffTime > 1.0f)
        
            m_fTime1 = m_fTime2;
            m_fFPS= m_iFramesElapsed / ( m_fDiffTime );
            m_iFramesElapsed = 0;
        
        */
    

    //----------------------------------------------------------
    // Name:    CTimer::GetTime - public
    // Desc:    Get the current time since the program started
    // Args:    None
    // Rets:    float: 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::GetElapsedSeconds - public
    // Desc:    Get the elapsed seconds since the last frame was drawn.
    // Args:    elapsedFrames:
    // Rets:    float: The time elapsed since the program started.
    //----------------------------------------------------------
    float GetElapsedSeconds(unsigned long elapsedFrames = 1)
       return m_fDiffTime;     

    //----------------------------------------------------------
    // Name:    CTimer::GetFPS - public
    // Desc:    Get the current number of frames per second
    // Args:    None
    // Rets:    float: the number of frames per second
    //----------------------------------------------------------
    inline float GetFPS( void )
       return m_fFPS;  
;

#endif // _E_TIMER_H

【讨论】：

这门课太棒了！如果可以的话，我会给你两个赞成票。我将它用于流畅的鼠标外观代码和玩家移动。

【参考方案2】：

在 c++ 中，我最喜欢的计时器与史蒂夫建议的相同。

在你的 opengl 应用程序中也可能存在禁用 vsync 的问题，对我来说它一直默认开启，你必须加载一些功能来禁用它。

至于可能更独立于平台的解决方案，

使用时间.h

我不记得函数了

// in your loop:

//////////

static int lastTime = GetTime();

static int framesDone = 0;

int currentTime = GetTime();

if(currentTime > lastTime)



     int fps = framesDone;

     framesDone = 0;

     lastTime = currentTime;



framesDone++;

/////////

但是，对于 Windows，第一个答案是最好的。

如果您在禁用垂直同步方面需要帮助，请告诉我们。