What's left to sim?

"Peter" > wrote in message
.. .
> In article . 52>,

> Cheers to those who put me straight. So are HFB's being simulated in
> some sims? I remembered an old discussion here on ras which, after some
> google groups research, may have been to do with GPL and some time ago,
> that said that pc's weren't fast enough to simulate them. Has that
> changed now?
> --

Yes, in numerous sims. But for just one (easy to paste) example, here's the
basic track variable stanza from the terrain.ini file in ISI's latest,
rFactor (though similar lines are in its predecessors as well). Note there
are high-frequency bump length and amplitude values for three different road
surface types.

[TRACKVARS]
RoadDryGrip=1.00
RoadWetGrip=0.80
RoadmetalGrip=0.80
RoadDustGrip=0.90
RoadBumpAmp=0.010
RoadBumpLen=13.0
RumbleDryGrip=0.95
RumbleWetGrip=0.60
RumbleBumpAmp=0.015
RumbleBumpLen=8.0
MiscBumpAmp=0.08
MiscBumpLen=4.0

There are also other stanzas in the file that modify these HF variables as
well as add more for washboard bumps, road cracks, cement patches, dusty
berms, grass, gravel and rumblestrips.

SB

>From: Peter
>Date: 11/23/2004 6:27 A.M. Central Standard Time
>Message-id: >
>
>In article . 52>,
says...
>> Peter > wrote in
>> :
>>
>> > In article >,
>> > says...
>> >> On Sun, 21 Nov 2004 15:10:48 -0000, Peter
>> >> > wrote:
>> >> >That watchamacallit to do with being able to emulate the bumps on the
>> >> >road. Yeah, I forget the name and I'm pressed for time to look it
>> >> >up. <BG> Unfortunately, we'll need sims that run at 1000fps I'd
>> >> >guess.
>> >>
>> >> High frequency bumps? BTW, the fps don't matter when you're talking
>> >> physics...
>> >>
>> >> Cheers!
>> >>
>> >> Remco
>> >>
>> >>
>> > Eh? Are you saying that simulating high frequency bumps is nothing to
>> > do with physics? They certainly would be in my world coz they're going
>> > to affect how the car behaves. And I thought hfb could not be
>> > reproduced in an effective enough way because, in the time it takes to
>> > jump from 1 frame to the next, the car would have travelled too far
>> > along the track in order to allow for hfb's to be simulated correctly.
>> > Hence more fps required.
>>
>> He said that simulating HFB has nothing to do with fps. FPS reflects how
>> often the image is drawn on the screen. When the time to draw the next
>> frame arrives, renderer takes the current state from the physics engine
>> (which may either operate on higher frequency or use continuous model, or
>> combination of both).
>>
>> Alex.
>>
>Cheers to those who put me straight. So are HFB's being simulated in
>some sims? I remembered an old discussion here on ras which, after some
>google groups research, may have been to do with GPL and some time ago,
>that said that pc's weren't fast enough to simulate them. Has that
>changed now?
>--
>Pete Ives
>Remove All_stRESS before sending me an email
>

Depends really on what you would define to be high frequency. The frame rate
and physics sampling rate are two seperate things. If they weren't time would
speed up and slow down right along with the frame rate. What you do is move
the car several times between each graphics frame that's drawn. So if you're
"physics frequency" is 300Hz, that means in the code you're actually moving the
car 300 times per second. I.e., you'd need a frame rate of 300 to see
everything the car is actually doing.

If your graphics are running at 30 fps, then the car is moving 10 times, then
the graphics are drawn, etc.. So when talking about high frequency bumps it's
not frame rate dependent at all. Instead, it's about the physics engine
sampling frequency (the 300, not the 30).

How far can the car go in 1/300th of a second? If there's a bump smaller than
that then the car will drive right through it without seeing it. In practice
the car will sort of go through a bump that's quite a bit longer than that, I'd
think at least 4 times the size.

So the smallest bump you'd probably feel consistently at 100mph would be:

With:
1/300 = 0.0033333.... * 4 = .01333333... seconds of travel

100mph = 146.67 ft/sec

146.67 ft/sec * 0.0133333... = 1.95 feet

And that would be a bit inconsistent too, sort of the limit in a way. I.e., if
there was a bump 2 feet long and you drove "through" it at 100mph you would
definitely hit it every time, but you'd hit it a little differently on each lap
probably. I.e., a wheel would hit the bump 4 times with as you passed, but you
might hit the peak on one and not another pass.

At 200mph of course you'd be at about 4 feet minimum wavelength then. Seems
it's worse than I thought. Granted, if one sat to think about this a bit, this
sort of standard limitation could undoubtedly be overcome :-)


Todd Wasson
Racing Software
http://PerformanceSimulations.com
http://performancesimulations.com/scnshot4.htm

"Dave Henrie" > wrote in message
. 97.136...

<snip<

> (this is a topic I've covered about once a year for the last 4 or5 years)
> An online pitcrew sim. 7 or 8 guys sit around and do nothing for 30
> minutes, then they all jump over the wall, change the tires and jump back
> over the wall. One player, the crewchief, makes the calls for tire
> pressure, wedge adjustment etc. A Doom3 engine or Halflife would make an
> excellant base for such a sim. You could even meld in a real racing sim,
> so that the driver needs to recruit the country's best online pitcrew.
> Crews could be like hired professionals, pitting for drivers in various
> leagues all over the world.
> you'd need voice comms, you'd need telemetry, you'd need a way to
> interact with the racing sim itself...sheesh...a couple of weeks coding
> right???
>
> dave henrie
> ps...due to the limitations F1 always puts on multiplayer, you could have
> a bigger crew..but they could only hotseat compete against another team
> at the same site.
> dh

Oh Yea? But what would happen if one of the crew members git's sent
a'packin for the weekend? Where would he watch the race from? City 17?

In ten years I predict that the West Brothers will have at least one more
update on their website...oh...and buy a new cat.

Mike

Damage.

-Larry

"John DiFool" > wrote in message
...
> I mean issues like tires, drafting, variable weather,
> better FF and AI, etc., and not new types of cars or
> series necessarily. In other words what kinds of stuff
> still bears to be improved upon (or even invented),
> and what has been pretty much optimized? What will
> we see 5-10 years down the road? [Pun kind of
> intended...]
>
> When I watch a NASCAR telecast I get the impression
> that a lot more is going on than there is in either of our
> NASCAR titles, as teams feverishly try to tweak the car
> back to optimum during a race. [Not that you'll get a
> lot of this technical info from the announcers, just a
> bunch of stuff like "Gordon is tight in the middle of the
> turn, loose on exit"...].
>
> John DiFool
>