From: Kero <kero@...>
Date: 2005-11-11T18:07:13+09:00
Subject: Re: Accurate Timing in ruby

> Believe it or not, I'm attempting to make an action-driven game with ruby
>   Is there a way to get the time in milliseconds since the program start
> ed, or something similar?  I've tried using Time.now.to_f, but all too of
> ten that value will be the same in two consecutive update calls, causing
> jumps in motion and "infinite" fps readings.

I typically & rather consistently get: 

  irb(main):003:0> Time.now - Time.now
  => -5.0e-06

meaning Ruby evaluates from right to left and my clock is running
nice and smooth (on microsecond level)

I fear what you see is not Ruby's fault, but your hardware/OS clock.
1) your hardware is so fast that the consecutive calls have no
   significant distinguishing bits left (I have 2 or 3 bits left on 700
   MHz; you may need nanoseconds instead of microseconds)
2) your OS is not updating its system clock often enough

Even though windows has nasty habits when updating time to a central
server, I do not think it suffers from 2)

You don't round to milliseconds before you compute the fps, do you?
Then you would get zero whenever you're near 1000 fps (which --depending
on the action-- is quite possible on today's hardware; even my puny CPU
and reasonable graphics card have 1200fps on the glxgears test)

Hth,
Kero.

+--- Kero ---------------------------------- kero@chello@nl ---+
|  The last good thing written in C++ was the Pachelbel Canon  |
|  Jerry Olson                                                 |
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