Re: Lua speed (was class implementation)

[Chris Marrin <chris@...>]

Jamie Webb wrote:
> On Tue, Apr 04, 2006 at 03:48:22PM -0700, Chris Marrin wrote:
> > Kerry Thompson wrote:
> > > ...
> > > Interesting. I can see from what you, David, and Chris wrote that singling
> > > out 3D wasn't the best way to get my point across. Let me phrase it another
> > > way: I wouldn't want to do a high-speed twitch game using Lua to do event
> > > handling. Hard-core gamers can tell (and will complain) when a game takes
> > > 1/100th of a second to respond.
> > Hmmm. I've seen UI studies that show that humans can't discriminate 
> > events that are less than 20ms (or 1/50th of a second) apart.
>
> We may not be able to distinguish events that close together, but we
> can certainly expect to time our actions to within 10ms. For example,
> when returning a serve, a top tennis player must hit a ball moving at
> something like 150km/h using a racquet with a 'sweet spot' maybe 10cm
> in diameter. In 10ms, that ball has moved almost half a metre!
>
> Given one racquet that somehow had even 1ms latency, and another that
> didn't, I suspect our tennis pro could readily tell them apart, even
> though he couldn't actually observe any difference.
>
> Applying the same logic to games, a player may 'feel' a 10ms delay
> even though his monitor may not refresh fast enough to have much chance
> of actually seeing it.

But typical video games only refresh at 60Hz, which is 17ms. Even a 
great card might hit 120fps, which is around 8.5ms. The worst case 
system response, if an event is received right after a frame starts 
rendering, is double that, or 17ms. That means 17ms between the time a 
button is pressed and the response is seen on the screen, assuming 0 
event latency and 0 time to process the event. So I just don't see the 
"gamers will notice a 10ms delay" argument. That's way below the 
theoretical limit.

--
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