benching the GL

When I want to measure fps I often do something like this in the DisplayFunc:

#ifndef NDEBUG
  boost::timer timer;
#endif // NDEBUG




#ifndef NDEBUG
  glutSetWindowTitle(cformat("%.2f", 1 / timer.elapsed()).c_str());
#endif // NDEBUG

The boost::timer comes from the boost library and is a wrapper around clock(), cformat() is a wrapper around vsnprintf().

The problem is that many times, on a fast graphics card, I get infinite fps as a result. That is, it is as if no time has elapsed in the rendering loop. Is there a portable way to achieve accurate timing? Should I use the GL timer extension?

From a cursory glance on the Boost doc, this timer.elapsed() returns time in INTEGER SECONDS ! Expecting to do something usefull with that on a single frame is beyond me …

You may want to average fps during one second, ie. count number of rendered frames and display this number each time timer.elapsed() changes (each second).

You are wrong:

double elapsed() const;                // return elapsed time in seconds

Nothing prevents this method from returning say .001 seconds or .000001 seconds as the elapsed time and it is returning a double thus allowing high resolution. The fps average idea is good, but how to handle infinite fps?

The fps average idea is good, but how to handle infinite fps?

1: Stop using a bad timer. Boost.Timer is a bad (or at least unreliable) timer.

2: Stop measuring frames per second. If you’re only going to look at one frame, the useful measurement is milliseconds, not FPS.

Can you suggest a portable timer I should use for more reliable time measurements?