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Thread: How to count frames?

  1. #1
    Senior Member Regular Contributor
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    How to count frames?

    I have got a "simple" question:

    How can I get the current framerate of my OpenGL programm.

    I count how often my drawing function is called in one second, but is this really the true framerate?

    What´s with buffer swapping / flipping and such things? Is there a better way to count fps?

    Diapolo

  2. #2
    Senior Member OpenGL Guru Humus's Avatar
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    Re: How to count frames?

    Your method is correct. But you can also count the framerate by messuring the time it takes to render a frame, this will not be updating only once per second. The most accurate way to do this is to use this functions:

    __inline __int64 GetCycleNumber(){
    //RDTSC instruction
    __asm _emit 0x0F __asm _emit 0x31
    }


    int GetMHz(){
    LARGE_INTEGER t1,t2,tf;
    __int64 c1,c2;

    QueryPerformanceFrequency(&tf);
    QueryPerformanceCounter(&t1);
    c1 = GetCycleNumber();
    //Just wait a little
    for (int t = 0; t < 5000000; t++);
    QueryPerformanceCounter(&t2);
    c2 = GetCycleNumber();

    return (int) ((c2 - c1) * tf.QuadPart / (t2.QuadPart - t1.QuadPart) / 1000000);
    }

    Time = (ThisCycleNumber - LastCycleNumber) / (1000000 * MHz);

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