Re: [AD] Framerate under the 4.1.x WIP Windows builds is mysteriously slow.

[Andrei Ellman <ae-a-alleg@xxxxxxxxxx>]

Oscar Giner wrote:

> ... This seem to show that
> retrace_count is not updated as often as it should, because it does
> two loops (I also get around 35fps).
>
> In other words, a bug or not, retrace_count is not very accurate (it's
> increase 85 times per second (in my case) but not evenly).
>
> The accuracy is pretty low, however.


Elias Pschernig wrote:

> No - it"s simply a variable increased in a timer. Not much point using
>  it for anything, you can as well create your own timer.


I thought that on hardware that supported vertical-retrace interrupts, 
retrace_count would automatically synch itself with the card's retraces. 
If retrace_count is nothing more than an inaccurate timer that is not 
updated as often as it should be, then there does not seem to be much 
point in using it.

Incidentally, I used to crerate a timer of my own instead of use 
retrace_count. I once installed a program of mine on a friend's machine 
that uses Linux. It was the first time I had seen my program run on 
Linux (previously, I've seen it run on Windows and DOS). It used Allegro 
4.0.3. The program ran normally, but there appeared to be a shear that 
consisted of a vertical line moving upwards very slowly and then 
starting from the bottom (it took about 5-10 seconds). If I disabled the 
vsync() command, there would still be noticable shearing, but then, the 
shearing would be jumping around all over the place. The conclusion that 
I got from that was that my own timer was ever so slightly off (and that 
vsync() was also inaccurate in this case), so I decided to use 
retrace_count in the hope that it would synchronise to the monitor's 
refresh-rate if possible (I never did get to test the retrace_count 
version of that program on my friend's machine).

AE.