OpenEuphoria

Re: Controlling Speed

• Posted by Robert B Pilkington <bpilkington at JUNO.COM> Nov 03, 1998
• 658 views

>This code has some shortcomings, I know...
>1) What happens when the internal Euphoria time() function has to
>reset to 0. This would seem to kill my delay() procedure immediately.
RDS:
>How big a number can time() return?

I think it's 24 hours. I was running a screen saver I made using a delay
routine like yours, and it hung after about 24 hours. (It was hung when I
got back.)

>2) This only works if the delay() procedure is imbedded into a main
>loop that is executing constantly. It does not slow down a program
unless
>it is called relatively constantly.

Most delay routines are like that, so I don't consider it a shortcoming.
:)

>3) Calling delay() just 1 time won't necessarily cause a delay. If
>delay() is called milliseconds before last_time + delay_time will be >
>time() then the procedure will not cause a noticeable pause.

That's good for games: If the drawing/processing takes less than one
clock tick (about .05 seconds at the default 18.2 ticks/second), then the
framerate is set to 18 frames a second, just as long as the
drawing/processing takes place anywhere less. If it takes longer, the
game slows to half speed (or less, if the drawing/processing takes too
long.).

Here's my generic delay() routine: (Untested, written on the fly, but I
use it! 

procedure tick_delay(integer ticks)
    atom oldtime

    for i = 1 to ticks do
        oldtime = time()
        while oldtime=time() do -- nothing
        end while
    end for
end procedure

tick_rate(30) -- include machine.e to get it. Sets framerate to 30, so
              -- tick_delay(1) will delay 1/30th a second, tick_delay(2)
              -- for 2/30th (1/15th), and so on. This line is optional,
of
              -- course, if you want 18 frames a second.


This way, even if the clock resets, oldtime will not equal time(), so the
loop will continue.


I think this is like the 3rd time I've mentioned this little routine...
:)
(One of them was to just one person, though.)