rec.autos.simulators

by **Sébastien Tixie** » Sat, 01 Jul 2000 04:00:00

Hi !

The thing that really***me off in GPL are the AI that are IMHO bad,
i.mean. they can do good times but they don't have the same physics than
the player , and even NO physics !!! So they can do impossible things
like, that would put them out the tracks or slower ( cold tire, lots of
fuel ).

So my questions is

Do GP3's AI has the same physics than the player ? or simplyfied physics
( for example simplified suspension,engine,etc...), or NO physics at all
( trajectory line interpolated .. bah.... crapy shit ...)

--
Sebastien Tixier
Susuki 650 SVS - No Driving Licence yet
(MagicFr) GPLRank handicap -17.05
Game Developper ( A.I. in V-Rally2, Need For Speed 5 PSX )
personal : http://www.racesimcentral.net/
company : http://www.racesimcentral.net/

by **Jo Hels** » Sat, 01 Jul 2000 04:00:00

On Fri, 30 Jun 2000 10:08:38 +0200, =?iso-8859-1?Q?S=E9bastien?=

>Hi !

>The thing that really***me off in GPL are the AI that are IMHO bad,
>i.mean. they can do good times but they don't have the same physics than
>the player , and even NO physics !!! So they can do impossible things
>like, that would put them out the tracks or slower ( cold tire, lots of
>fuel ).

>So my questions is

>Do GP3's AI has the same physics than the player ? or simplyfied physics
>( for example simplified suspension,engine,etc...), or NO physics at all
>( trajectory line interpolated .. bah.... crapy shit ...)

And you really expect somebody to know? :-)

JoH

by **Sébastien Tixie** » Sat, 01 Jul 2000 04:00:00

Well, some say they play GP3, so maybe they have seen strange AI behaviour or
not.
That could be a clue.

When you see GPL AI, you can see quite easily that it use trajectories
interpolation.

--
Sebastien Tixier
Susuki 650 SVS - No Driving Licence yet
(MagicFr) GPLRank handicap -17.05
Game Developper
personal : http://magicfr.multimania.com
company : http://www.eden-studios.fr

by **Simon Brow** » Wed, 05 Jul 2000 04:00:00

No sim can possibly afford to use the same physics model for the AI cars as
for the player. And if they could, writing AI code that could cope with
realistic physics would take a 100 programmer team fifty years to code.
Imagine trying to write an AI routine to drive GPL!!! <shudder> :)
All AI opponents in all racing sims are to a large extent running on
"rails". It is more noticeable in GPL because of the extreme driving style.
GP2 also used a similar system, and presumably so will GP3. The trick is to
make is "look" real.
The main problem I have with the GPL AI is when they hit me in braking
zones. :)

by **Sébastien Tixie** » Wed, 05 Jul 2000 04:00:00

With simplified physics its very possible.
I can't tell you much, but i worked on V-Rally 2 and NFS5 psx.
If i compare their physics with GPL, i would say, we don't have toe-in/out
settings on wheels, less complex differential and relieved body inertia.
Imagine you make a GPL simplified physics, simplified tire grip, simplify
suspension, etc...
So you only need 1 developper and 6month to have your real driving AI.
That the time i spent on real driving AI on V-Rally 2 and NFS5 PSX plus cops and
traffic cars.
Maybe it's possible maybe not, i beleive it is.

And if it's sound to complex maybe they could just calculate the real collisions
between the car, i can't stand see an GPL AI push me, then i go into spin, and
the AI don't even slide !!!

> No sim can possibly afford to use the same physics model for the AI cars as
> for the player. And if they could, writing AI code that could cope with
> realistic physics would take a 100 programmer team fifty years to code.
> Imagine trying to write an AI routine to drive GPL!!! <shudder> :)
> All AI opponents in all racing sims are to a large extent running on
> "rails". It is more noticeable in GPL because of the extreme driving style.
> GP2 also used a similar system, and presumably so will GP3. The trick is to
> make is "look" real.
> The main problem I have with the GPL AI is when they hit me in braking
> zones. :)

regards,
--
Sebastien Tixier
Susuki 650 SVS - No Driving Licence yet
(MagicFr) GPLRank handicap -17.05
Game Developper
personal : http://magicfr.multimania.com
company : http://www.eden-studios.fr

by **Simon Brow** » Wed, 05 Jul 2000 04:00:00

Yes, but I said no "sim" can have the same physics for the AI cars and in my
opinion those game you mention probably are not sims (although I haven't
played either). The amount of physics calculations in GPL is probably more
than ten times that in NFSPU. I think I read somewhere that the GPL phsyics
runs at 288 Hz!

by **Andy Marso** » Wed, 05 Jul 2000 04:00:00

I have never had the AI hit me in braking zones, I've played GPL ever since
it came out.
This seems to be common problem for quite a few people. Is it just that
you're braking too early or something? seems a bit strange to me....

by **Jan Loebzie** » Wed, 05 Jul 2000 04:00:00

On Tue, 04 Jul 2000 08:56:05 +0200, Sbastien Tixier

>That the time i spent on real driving AI on V-Rally 2 and NFS5 PSX plus cops and
>traffic cars.

No offense, but I wouldn't call the AI of the cops and traffic cars in
NFS5 a 'plus'. :-)
(can only talk about the PC version though)

Blaze

by **Sébastien Tixie** » Wed, 05 Jul 2000 04:00:00

> > The main problem I have with the GPL AI is when they hit me in braking
> > zones. :)

> I have never had the AI hit me in braking zones, I've played GPL ever since
> it came out.
> This seems to be common problem for quite a few people. Is it just that
> you're braking too early or something? seems a bit strange to me....

Braking too early ! I don't think so :o)

--
Sebastien Tixier
Susuki 650 SVS - No Driving Licence yet
(MagicFr) GPLRank handicap -17.05
Game Developper
personal : http://magicfr.multimania.com
company : http://www.eden-studios.fr

by **Sébastien Tixie** » Wed, 05 Jul 2000 04:00:00

> On Tue, 04 Jul 2000 08:56:05 +0200, Sbastien Tixier

> >That the time i spent on real driving AI on V-Rally 2 and NFS5 PSX plus cops and
> >traffic cars.

> No offense, but I wouldn't call the AI of the cops and traffic cars in
> NFS5 a 'plus'. :-)
> (can only talk about the PC version though)

The AI in NFS version PC is an offense for AI developper IMHO.
I'm talking about the PSX version that i've coded, and i can assure you that there
driving like they has a steering wheel and pedals !

--
Sebastien Tixier
Susuki 650 SVS - No Driving Licence yet
(MagicFr) GPLRank handicap -17.05
Game Developper
personal : http://magicfr.multimania.com
company : http://www.eden-studios.fr

by **Sébastien Tixie** » Wed, 05 Jul 2000 04:00:00

> Yes, but I said no "sim" can have the same physics for the AI cars and in my
> opinion those game you mention probably are not sims (although I haven't
> played either). The amount of physics calculations in GPL is probably more
> than ten times that in NFSPU. I think I read somewhere that the GPL phsyics
> runs at 288 Hz!

I totally agree with you !
Maybe it's to hard for me to explain it in English and you don't understand what
i try to explain :o(((

I mean,
simplified AI car physics + AI driving
IS BETTER THAN
AI on static interpolated trajectory line

IMHO.

with "my" method you can't see an AI has strange car behaviour, like, slide
driving when overtaking or thing like thats because they has real car physics (
very simplified ).

king regards,
--
Sebastien Tixier
Susuki 650 SVS - No Driving Licence yet
(MagicFr) GPLRank handicap -17.05
Game Developper
personal : http://magicfr.multimania.com
company : http://www.eden-studios.fr

by **Eldre** » Wed, 05 Jul 2000 04:00:00

>> The main problem I have with the GPL AI is when they hit me in braking
>> zones. :)

>I have never had the AI hit me in braking zones, I've played GPL ever since
>it came out.
>This seems to be common problem for quite a few people. Is it just that
>you're braking too early or something? seems a bit strange to me....

If I brake early enough for ME to make the corner, any AI close behind will
either hit me(if I'm on the racing line), or make a bonzai pass to the
inside(if I'm wide of the line). Not much fun to see them go by at 10mph
faster when I'm scrambling for traction as it IS...

Eldred
--
Tiger Stadium R.I.P. 1912-1999
Homepage - http://www.umich.edu/~epickett
GPL hcp. +70.45

Never argue with an idiot. He brings you down to his level, then beats you
with experience...
Remove SPAM-OFF to reply.

by **TToomm** » Wed, 05 Jul 2000 04:00:00

eldredp wrote;

A simple and common way of dealing with this is to edit
the gpl_ai.ini file in your gpl folder. Near the bottom:
braking_efficiency_coeff = 0.8000
change it to 1.9 and the AI can come to a dead stop instantly
when caught in heavy traffic. It also adds about a second to
their laptime. 1.0 or 1.2 works well and still looks fairly realistic.

The ultimate method is to edit the race.lp file and change
the braking points at the specific corner. There is a utility
out there by Francois Dubuc. Use it to convert the race.lp
file from the desired track folder to a txt file. Then use notepad
to edit it. Don't touch the first 3 lines. The first field is the target
speed for the AI. Scroll down the file until you see a high value
followed by a sharp dropoff. That is a corner following a long straight.
Just move the drop in speed sooner a bit. Don't change the other
fields, so you can't just cut and paste, you have to do some typing.
Use the editor to convert back to lp format.
And now you get respect!

Tom

by **Eldre** » Thu, 06 Jul 2000 04:00:00

Ok, thanks. I'll try the first method first. It's easier.<g>

Eldred
--
Tiger Stadium R.I.P. 1912-1999
Homepage - http://www.umich.edu/~epickett
GPL hcp. +70.45

Never argue with an idiot. He brings you down to his level, then beats you
with experience...
Remove SPAM-OFF to reply.

by **Sébastien Tixie** » Thu, 06 Jul 2000 04:00:00

When I read all this, why how we call them AI ?
I'm now calling them AD.
Artificial Drivers, because it's a shame to say they're Intelligent :
- breaking point
- race.lp

please take a look at real AI : ( my bot is Magic )
http://www.ebc.ee/~mremm/rars/rars.htm

regards,
--
Sebastien Tixier
Susuki 650 SVS - No Driving Licence yet
(MagicFr) GPLRank handicap -17.05
Game Developper
personal : http://magicfr.multimania.com
company : http://www.eden-studios.fr

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