如何在OpenGL中计算FPS？

void CalculateFrameRate()
{    
    static float framesPerSecond    = 0.0f;       // This will store our fps
    static float lastTime   = 0.0f;       // This will hold the time from the last frame
    float currentTime = GetTickCount() * 0.001f;    
    ++framesPerSecond;
    if( currentTime - lastTime > 1.0f )
    {
        lastTime = currentTime;
        if(SHOW_FPS == 1) fprintf(stderr,"\nCurrent Frames Per Second: %d\n\n",(int)framesPerSecond);
        framesPerSecond = 0;
    }
}

我应该在void play(void)或void display(void)中调用此函数吗？

或者它没有任何区别？