rec.autos.simulators

by **Sébastien Tixie** » Sat, 04 Aug 2001 02:53:15

you'r welcome, there so much works to do to program a good car physics :o)

With my colegue, we worked 8 hours a day for several month, on the one we
made for our game at work, and we still have some works on ground resistive
force , when "uploading" information from tire to engine through gearbox and
differentials :o)

regards,
--
Sbastien TIXIER - Game Developer
Dynamics and Car Physics
Overall GPLRank -42.97
Monster GPLRank -116.28

by **Ruud van Ga** » Sat, 04 Aug 2001 02:54:11

On Thu, 2 Aug 2001 17:56:06 +0200, "Sbastien Tixier"

>Another question... do you simulate differential ( front, rear and central )
>?

Just 1 rear diff. I know for 4WD you have to have 3. How do you handle
3 interacting differentials? Is it a mess or a clean pipeline of
differentials in your simulation?

You can change the differential in the car.ini; mainly the locking is
important. It's a viscous diff, with a locking coefficient set to 100
by default. Values from 0 (open) to 200 (locking hard) may be
realistic and useful, but I did little experimenting.

Certainly! Makes a whole lot of difference. One of the primary
handling things in the cars.

Ruud van Gaal, GPL Rank +53.25
Pencil art : http://www.marketgraph.nl/gallery/
Free car sim : http://www.marketgraph.nl/gallery/racer/

by **Ruud van Ga** » Sat, 04 Aug 2001 02:58:44

>> v0.4.8 will probably have caster, thanks to Gregor (I should subtitle
>> it Veble Racer, lol), mr. Formula Wizard. That's something GPL doesn't
>> have. :) (but N4 does, ah well) And let's throw in some toe, should be
>> easy enough, an offset.

>what the hell is this toe-thing, anyway?

It's rotating the wheels inside (toe in) or outside (toe out), in the
center of steering position. Seems to add some stability to turn-ins.

Ruud van Gaal, GPL Rank +53.25
Pencil art : http://www.marketgraph.nl/gallery/
Free car sim : http://www.marketgraph.nl/gallery/racer/

by **Sébastien Tixie** » Sat, 04 Aug 2001 03:10:40

we store the car with quaternions every 10 frames ( 60 fps ) and interpolate
values, works great :)

--
Sbastien TIXIER - Game Developer
Dynamics and Car Physics
Overall GPLRank -42.97
Monster GPLRank -116.28

by **Sébastien Tixie** » Sat, 04 Aug 2001 03:36:13

> On Thu, 2 Aug 2001 17:41:13 +0200, "Sbastien Tixier"

> Weird, skid sounds are not always on here. What sound card do you
> have? Even then, I believe you can see the skidfactors on the left,
> and when added up they set a skid volume from 0..1.

I just check, i have skidding sound even with 0 skidfactors.
I have a sound blaster live deluxe with liveware 3 and Win2000, setup with 4
speakers.

--
Sbastien TIXIER - Game Developer
Dynamics and Car Physics
Overall GPLRank -42.97
Monster GPLRank -116.28

by **Ruud van Ga** » Sat, 04 Aug 2001 04:13:18

On Thu, 2 Aug 2001 20:10:40 +0200, "Sbastien Tixier"

>> Yes, replays are very important, just to review the great moments, and
>> for a ghost car too. I'll record car positions, since the system is so
>> complex that I'd rather just store the pos/rot variables. Esp. if you
>> change the car physics a bit (like inertia values), your replays would
>> become unusable if you just stored driver inputs.

>we store the car with quaternions every 10 frames ( 60 fps ) and interpolate
>values, works great :)

That's 6Hz then? I had thought of 10Hz, or in any case something that
may be quite the same as the multiplayer network frequency. (I believe
Quake uses 20Hz network frequency)

Ruud van Gaal, GPL Rank +53.25
Pencil art : http://www.marketgraph.nl/gallery/
Free car sim : http://www.marketgraph.nl/gallery/racer/

by **Sébastien Tixie** » Sat, 04 Aug 2001 04:33:37

oups, i forgot to say that we worked on PS2, so we don't have memory to
waste ;o) we got only 32mb to store every thing, track included !!!
We try with only 3fps but the interpolation was not strong enough and the
car handled strangely in the replays :o)

But it's a lot more that on the PS1 wich had only 2mb !! on PS1 we were
forced to store user controls each frame and compress them in real time
because storing car informations ( position, rotation, wheel angle,
suspension stroke, tire grip for GFX/SFX) was really too much memory, so in
fact the replay was a replay of the driver not a movie :o)... so we didn't
have a "rewind" button in our replay :o)

well, got to go to sleep, tomorow i'll have 12hours of road drive,to go to
Espana for my 2 weeks vacancies.

Don't work to hard look at the sun sometimes ;o))))

cheers,
--
Sbastien TIXIER - Game Developer
Dynamics and Car Physics
Overall GPLRank -42.97
Monster GPLRank -116.28

> On Thu, 2 Aug 2001 20:10:40 +0200, "Sbastien Tixier"

> >> Yes, replays are very important, just to review the great moments, and
> >> for a ghost car too. I'll record car positions, since the system is so
> >> complex that I'd rather just store the pos/rot variables. Esp. if you
> >> change the car physics a bit (like inertia values), your replays would
> >> become unusable if you just stored driver inputs.

> >we store the car with quaternions every 10 frames ( 60 fps ) and
interpolate
> >values, works great :)

> That's 6Hz then? I had thought of 10Hz, or in any case something that
> may be quite the same as the multiplayer network frequency. (I believe
> Quake uses 20Hz network frequency)

> Ruud van Gaal, GPL Rank +53.25
> Pencil art : http://www.marketgraph.nl/gallery/
> Free car sim : http://www.marketgraph.nl/gallery/racer/

by **Pat Dotso** » Sat, 04 Aug 2001 06:28:01

Hmm, I definitely don't find it undrivable. It's
definitely not ready for prime time, but generally
speaking I'd place in on a level with GPL and N4
in terms of providing a feel for the handling of
the car.

The one biggest place that I see RACER shining is
in the way the front wheels catch oversteer. I've
never gotten that feeling from any other sim in
the way I do from this one. The force feedback
is pretty much as good or better than anything else.
I think it's more responsive than anything else.

--
Pat Dotson

> well, i think it's almost undrivable for now, but the idea is GREAT.

> IMO, there's works on suspension to do .

> --
> Sbastien TIXIER - Game Developer
> Overall GPLRank -42.97
> Monster GPLRank -106.02

> > Is it me, or is this the coolest thing in a long time?

by **Pat Dotso** » Sat, 04 Aug 2001 06:35:52

Do any of the cars currently available have
front wheel drive? For a while I thought
the Evoc did, but now I just think it's
underpowered :)

--
Pat Dotson

> On Thu, 2 Aug 2001 17:56:06 +0200, "Sbastien Tixier"

> >Another question... do you simulate differential ( front, rear and central )
> >?

> Just 1 rear diff. I know for 4WD you have to have 3. How do you handle
> 3 interacting differentials? Is it a mess or a clean pipeline of
> differentials in your simulation?

> >if not, this could be another reason why the car is so understeering and
> >it's VERY diifcult to keep the car on road when you manage to oversteer the
> >car.

> You can change the differential in the car.ini; mainly the locking is
> important. It's a viscous diff, with a locking coefficient set to 100
> by default. Values from 0 (open) to 200 (locking hard) may be
> realistic and useful, but I did little experimenting.

> >We saw at office that differntial is VERY important for the car handling...
> >especialy on 4WD cars !

> Certainly! Makes a whole lot of difference. One of the primary
> handling things in the cars.

> Ruud van Gaal, GPL Rank +53.25
> Pencil art : http://www.marketgraph.nl/gallery/
> Free car sim : http://www.marketgraph.nl/gallery/racer/

by **J. Todd Wass** » Sat, 04 Aug 2001 09:42:03

Not a bad idea. I currently have to write routines to allow the other
programmer on my project to design an interface for car setup.
Displaying/adjusting something simple like ride height or camber angle at
static ride height gets really complicated when the suspension is modelled more
fully with A-arms, inclined spring/shock angles, etc.. Besides, GPL does
suspensions the same way you're doing it from what I've heard so far, sooo.....
:-)

Todd Wasson
---
Performance Simulations
Drag Racing and Top Speed Prediction
Software
http://PerformanceSimulations.Com

by **Gunnar Horrigm** » Sat, 04 Aug 2001 19:55:42

> >> v0.4.8 will probably have caster, thanks to Gregor (I should subtitle
> >> it Veble Racer, lol), mr. Formula Wizard. That's something GPL doesn't
> >> have. :) (but N4 does, ah well) And let's throw in some toe, should be
> >> easy enough, an offset.

> >what the hell is this toe-thing, anyway?

> It's rotating the wheels inside (toe in) or outside (toe out), in the
> center of steering position. Seems to add some stability to turn-ins.

you mean like this?

toe in toe out

/ ---- \ \ ---- /
| |
| |
| |
|--------| |--------|

--
Gunnar
#31 SUCKS#015 Tupperware MC#002 DoD#0x1B DoDRT#003 DoD:CT#4,8 Kibo: 2
myk, trygg og god.

by **Gregor Vebl** » Sat, 04 Aug 2001 20:17:08

Wow, vehicle aerobics :).

Yes, that should be it.

-Gregor

> you mean like this?

> toe in toe out

> / ---- \ \ ---- /
> | |
> | |
> | |
> |--------| |--------|

> --
> Gunnar
> #31 SUCKS#015 Tupperware MC#002 DoD#0x1B DoDRT#003 DoD:CT#4,8 Kibo: 2
> myk, trygg og god.

by **Ruud van Ga** » Sat, 04 Aug 2001 20:28:55

On Thu, 2 Aug 2001 21:33:37 +0200, "Sbastien Tixier"

>oups, i forgot to say that we worked on PS2, so we don't have memory to
>waste ;o) we got only 32mb to store every thing, track included !!!
>We try with only 3fps but the interpolation was not strong enough and the
>car handled strangely in the replays :o)

Geez, I don't envy you. I just allocate memory as it comes. If a good
method requires more memory, so be it. That's the fun when you're
making a sim that doesn't have a base machine config behind it. :)

You'll probably miss this one, but happy holidays!

Not too much of that around here now. :(
But a good rule of life. :)

Ruud van Gaal, GPL Rank +53.25
Pencil art : http://www.marketgraph.nl/gallery/
Free car sim : http://www.marketgraph.nl/gallery/racer/

by **Ruud van Ga** » Sat, 04 Aug 2001 20:30:02

On Thu, 02 Aug 2001 16:35:52 -0500, Pat Dotson

>Do any of the cars currently available have
>front wheel drive? For a while I thought
>the Evoc did, but now I just think it's
>underpowered :)

Yes, at 0 rpm it does have quite little torque. You might want to edit
torque.crv.
You can make it front wheel drive by setting wheel0.powered=1 and
wheel1.powered=1 (and taking out wheel2.powered (=0) and wheel3
ofcourse).

Ruud van Gaal, GPL Rank +53.25
Pencil art : http://www.marketgraph.nl/gallery/
Free car sim : http://www.marketgraph.nl/gallery/racer/

by **Ruud van Ga** » Sat, 04 Aug 2001 20:31:57

On Thu, 02 Aug 2001 16:28:01 -0500, Pat Dotson

>Hmm, I definitely don't find it undrivable. It's
>definitely not ready for prime time, but generally
>speaking I'd place in on a level with GPL and N4
>in terms of providing a feel for the handling of
>the car.

>The one biggest place that I see RACER shining is
>in the way the front wheels catch oversteer. I've
>never gotten that feeling from any other sim in
>the way I do from this one. The force feedback
>is pretty much as good or better than anything else.
>I think it's more responsive than anything else.

Can I quote you in a commercial? ;-)

Ruud van Gaal, GPL Rank +53.25
Pencil art : http://www.marketgraph.nl/gallery/
Free car sim : http://www.marketgraph.nl/gallery/racer/

rec.autos.simulators

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