FPS - Frame per Second


Someone has a function (simple will be better) to display the FPS (frames par second) in a 3d world ?

Thanks a million

You could declare a gloab variable
int frame_counter = 0;
do frame_counter++ every frame.
ask every frame, if the standart timer says that one second passed. if yes, frame_counter is the FPS number, and you can set it = 0, and let the program continue … :slight_smile:

another way is if a variable timeElapsed is the number of milliseconds that have passed since your last draw, then timeElapsed/1000.0f is your fps for that precise frame. and if you’re doing any animation at all, you’re probably already keeping track of the time in milliseconds.

you can also keep a running average using the frame counting method and a start time. at any given point the average fps would be numFrames/((curTime - startTime)/1000.0f)

one thing to watch out for, though is that time granularity can sometimes vary, especially with winNT and 2000. glutGet(TIME_ELAPSED) can be rather innacurate on these os’s. if you look at microsoft’s documentation, you can increase this granularity (usually…it can return NOCANDO… i’ve not had it happen, but it could happen).

see http://msdn.microsoft.com/library/psdk/multimed/mmfunc_2q3p.htm for microsoft doc.

Though I’ve been doing OpenGL and SGI-GL
applications for many years, it wasn’t till
a few months ago that I decided that it
might be useful to compute and display
frame rates. This was partly due to the fact
that I started working on PCs. The answer
to your question is platform/OS specific.
In windows (I’m using NT 4.0) there’s a
function called ‘clock’ which returns a
system time (in milliseconds?). I just
call that function each time I enter my
draw routine, store the result, subtract
off the previous result, and divide by
a constant called ‘CLOCKS_PER_SEC’. That
gives me elapsed time in seconds to draw
my 3D scene once. The inverse of that is
your frame rate in units of frames per
second. I always display this in the lower
left-hand corner of my screen. I’ve found
it to be quite useful. I can now compare
my PC performance with performance of other
PC’s with faster CPUs and 3D OpenGL boards.
I can also see how much various rendering
functions slow me down. Good luck.


Thanks for your help !

Leyder Dylan

although I know how to implement basic techniques like these. I always end up wasting CPU process time. For example If I want to wait for 30 seconds, I don’t want the CPU doing cycles in a friggin while loop. Is there a better way to wait and not be wasting cpu cycles?

My guess is, that you’ll (program will) have to tell the OS to send your program a message at the goal time or something… if this is really complex… just tell me, otherwise, all help would be appreciated as always!!