Testing cars and tracks

[cotharyus]

I've been looking for a way to help out with this game, because frankly, it rocks, and I'd like to see it really come into it's own as one of the well known open source games. To that end, I have been looking through the code, and trying to familiarize myself with various bits of it (such as the colision engine, which I know currently has some issues) but I'm also wondering about testing new cars and tracks that people have submitted. I'm willing to do it if anyone wants to point out exactly how we get our hands on such things. I've already svn'd the trunk to look at the code, and I notice that it looks like the cars and tracks there are the same one's that are in the last release - has anything been added? Does anyone want to send me a car I can test? What's the best way to work this?

[joevenzon]

Most of our tracks are conversions from Racer, since we don't have a mature set of tools for track development yet. In fact, that's one area we could use some help if you have a lot of programming experience (writing a track editor). If not, we could always use help tuning the car settings so that all of the ones in the release feel similar where appropriate and different where appropriate. There haven't been many new cars or tracks flowing in for a while....

[cotharyus]

I'd love to help in any way I can. I terms of programing experience, I don't have much outside of unix network applications, which is why some of what I'm looking here (C++ mostly) is taking some getting used to coming from my lowly C background. In terms of settings for the cars, I will be more than happy to tweak something here and there - I've noticed a couple of places that some of the cars could use some work, most notably in the brake department.

[joevenzon]

That sounds like a good place to start. In terms of the coding, it's unfortunately not very tidy, and not a good example of what you're supposed to do in C++... but it works, which is better than really nice C++ code for a project that never got off the ground. :-)

[osiris]

Most of our tracks are conversions from Racer, since we don't have a mature set of tools for track development yet. In fact, that's one area we could use some help if you have a lot of programming experience (writing a track editor). If not, we could always use help tuning the car settings so that all of the ones in the release feel similar where appropriate and different where appropriate. There haven't been many new cars or tracks flowing in for a while....

I'm quite testing settings on the G4 but if a standard setting is set for SVN, what are we allowed to change from the original settings? Is there a power limit, a brake friction limit and stuff like that(I know about the 11000 RPM limit but is there such a thing for the time to shift gears and the number of gears) ?
I'm interested in this because I want to tune the G4 in a way that is possible and that looks possible, I will send it when it will be fine.

[thelusiv]

The settings for the car are in the data/cars/CAR/CAR.car file (where CAR is the name of the car). Just read through some of the .car files and you'll see how things are defined. There are shift delay settings, as well as gears and gear ratio settings.

[osiris]

I mean that we can't give the car too much power, too many gears, no shift-delay…
It has to be realistic so I want to know what are limits...

there is a peak-engine-rpm but how is the power band? Is it tunable?
I want to know if people use the red zone or not to adapt the ratios, I also need to have the power band(flexible or peaky) and the max number of gears (10 gears isn't realistic and I don't know if there are cars with more than 7 gears).
Can I also make particules lighter?
And what are coordonates? for example "position = 2.3, -1.11, -0.22" (I need to check the center of mass to adjust braking…)
You do a great job.

[joevenzon]

We're trying to keep the G4 as a realistic representation of the Ford GT40: http://en.wikipedia.org/wiki/Ford_GT40

The torque curve is fully customizable. To understand what the coordinates are it'd help to have the blender file for the model... as of yet there's no joe to blender import script.

[thelusiv]

Since we don't have a program to calculate center of gravity yet, when I set up the XS, I used a spreadsheet with physics formulas to calculate from the weight values I entered what the resulting center of gravity was. I had of course previously calculated where I thought (based on weight distributions) the center of gravity was, and then I compared the ideal one to the actual one, and when there was a discrepancy, adjusted the weights on the car, and the center of gravity is recalculated. Linked below is the spreadsheet I used to do this. It is in Open Document Spreadsheet format, so I hope you have OpenOffice or something similar.
http://clemsonlinux.org/~thelusiv/XS_wei...ravity.ods

[kcid]

Joe,

There is a blender file of the G4 in the art repository, it's a updated version of the current G4, so the quality has gone up

Regards,

Kcid

[osiris]

For now, I know the real Max RPM should be 6500, and brakes are asymetric : front are stronger than rear ones.
I don't know the torque but as the G4 can do 0-100 is under 4 seconds, I think that tires have better grip(for me, 0-100 is in 6 or 7 seconds, depending on my settings).
Can you give the magic formula for tires?

[joevenzon]

You get one form of the longitudinal forces and a scheme for combining the forces here:

http://www.racer.nl/reference/pacejka.htm

for more details you'll have to look at VDrift's source code (I rewrote the tire forces code from scratch, as Vamos was using a different force combining scheme) or google around a bit.

[osiris]

I've found some values on :
http://vamos.sourceforge.net/vamos-docs/Cars.html#Cars

my time is 1:15.600 for ruudskogen with this car.
my time is 8:52.548 for the ring with this car.

I know the torque isn't powerful enough so it's the next thing to do with brakes.

drive = RWD

[ steering ]
max-angle = 36.0

[ engine ]
position = 1.4, 0.0, -0.1
mass = 200.0
max-power = 4.100e5
peak-engine-rpm = 5750.0
rpm-limit = 6500.0
inertia = 1.0
idle = 0.025
start-rpm = 1000
stall-rpm = 500
fuel-consumption = 0.0001
torque-friction = 0.0015
torque-curve-00 = 1000, 425.4
torque-curve-01 = 2000, 468.95
torque-curve-02 = 2500, 523.0
torque-curve-03 = 3000, 530.0
torque-curve-04 = 3300, 545.19
torque-curve-05 = 3500, 554.36
torque-curve-06 = 3800, 567.43
torque-curve-07 = 3900, 571.22
torque-curve-08 = 4000, 579.98
torque-curve-09 = 4100, 584.75
torque-curve-10 = 4200, 587.77
torque-curve-11 = 4500, 593.53
torque-curve-12 = 5000, 615.71
torque-curve-13 = 5500, 636.03
torque-curve-14 = 5750, 650.01
torque-curve-15 = 6000, 605.28
torque-curve-16 = 6500, 501.16


[ clutch ]
sliding = 0.27
radius = 0.05
area = 0.12354
max-pressure = 4.0e5

[ transmission ]
gears = 6
gear-ratio-r = -3.135
gear-ratio-1 = 2.61
gear-ratio-2 = 1.71
gear-ratio-3 = 1.23
gear-ratio-4 = 0.94
gear-ratio-5 = 0.77
gear-ratio-6 = 0.63
shift-delay=0.10

[ differential ]
final-drive = 3.36
anti-slip = 400.0

[ fuel-tank ]
position = -1.2, -0.1, -0.26
capacity = 100.0
volume = 100.0
fuel-density = 0.8

[ suspension-front ]
spring-constant = 60000.0
bounce = 7000.0
rebound = 7500.0
travel = 0.4
max-compression-velocity = 10.0
camber = -2.0
caster = 5.0
toe = -2.0
anti-roll = 10000.0

[ suspension-rear ]
spring-constant = 45000.0
bounce = 5500.0
rebound = 6000.0
travel = 0.12
max-compression-velocity = 10.0
camber = -0.45
caster = 0.28
toe = 0.2
anti-roll = 10000.0

[ tire-front ]
radius = 0.29
rolling-resistance = 1.3e-2, 6.5e-6
rotational-inertia = 10.0
tread = 0.0
# Lateral force
a0=1.1
a1=-0
a2=1690
a3=800
a4=6.03
a5=0
a6=-0.359
a7=1.0
a8=0
a9=-0.00611
a10=-0.0322
a111=0
a112=0
a12=0
a13=0
# Longitudinal force
b0=1.0
b1=0
b2=1690
b3=0
b4=229
b5=0
b6=0
b7=0
b8=-10
b9=0
b10=0
b11=0
b12=0
# Aligning moment
c0=2.07
c1=-6.49
c2=-21.9
c3=-0.416
c4=-21.3
c5=0.0294
c6=0.0
c7=-1.2
c8=5.23
c9=-14.8
c10=0.0
c11=0.0
c12=-0.00374
c13=0.0389
c14=0.0
c15=0.0
c16=0.639
c17=1.69

[ tire-rear ]
radius = 0.2935
rolling-resistance = 1.3e-2, 6.5e-6
rotational-inertia = 10.0
tread = 0.0
# Lateral force
a0=1.1
a1=-0
a2=1690
a3=800
a4=6.03
a5=0
a6=-0.359
a7=1.0
a8=0
a9=-0.00611
a10=-0.0322
a111=0
a112=0
a12=0
a13=0
# Longitudinal force
b0=1.0
b1=0
b2=1690
b3=0
b4=229
b5=0
b6=0
b7=0
b8=-10
b9=0
b10=0
b11=0
b12=0
# Aligning moment
c0=2.07
c1=-6.49
c2=-21.9
c3=-0.416
c4=-21.3
c5=0.0294
c6=0.0
c7=-1.2
c8=5.23
c9=-14.8
c10=0.0
c11=0.0
c12=-0.00374
c13=0.0389
c14=0.0
c15=0.0
c16=0.639
c17=1.69

[ brakes-front ]
friction = 1.6
max-pressure = 3.0e6
bias = 0.5
radius = 0.1375
area = 0.01

[ brakes-rear ]
friction = 1.5
max-pressure = 3.0e6
bias = 0.5
radius = 0.1375
area = 0.01
handbrake = 1.0

[ driver ]
position = 0.0, 0.023, 0.0
mass = 90.0
view-position = -0.36, -0.16, 0.26

[ drag ]
position = 0.0, 0.0, -0.60
frontal-area = 2.0
drag-coefficient = 0.3

[ wing-front ]
position = 2.34, 0, -0.6
frontal-area = 0.2
drag-coefficient = 0
surface-area = 0.3
lift-coefficient = -0.5
efficiency = 0.95

[ wing-rear ]
position = -2.14, 0, 0.37
frontal-area = 0.2
drag-coefficient = 0
surface-area = 0.5
lift-coefficient = -0.9
efficiency = 0.95

[ wheel-FR ]
position = 1.45, -0.75, -0.48
roll-height = 0.2
mass = 30.0
restitution = 0.1

[ suspension-FR ]
position = 1.45, -0.60, -0.35
hinge = 0,0,-0.1

[ wheel-FL ]
position = 1.45, 0.75, -0.48
roll-height = 0.2
mass = 30.0
restitution = 0.1

[ suspension-FL ]
position = 1.45, 0.60, -0.35
hinge = 0,0,-0.1

[ wheel-RR ]
position = -1.34, -0.75, -0.48
roll-height = 0.2
mass = 30.0
restitution = 0.1

[ suspension-RR ]
position = -1.34, -0.60, -0.35
hinge = 0,0,-0.1

[ wheel-RL ]
position = -1.34, 0.75, -0.48
roll-height = 0.2
mass = 30.0
restitution = 0.1

[ suspension-RL ]
position = -1.34, 0.60, -0.35
hinge = 0,0,-0.1

[ contact-points ]
# used to find the bounds of the car (for collisions)
# also play into the weight distribution and balance
mass = 33
position-00 = -2.32, 1.11, -0.62
position-01 = 2.32, 1.11, -0.62
position-02 = -2.32, -1.11, -0.62
position-03 = 2.32, -1.11, -0.62

# these are used to calculate the weight distribution and balance
[ particle-00 ]
mass = 255
position = -2.3, 1.11, -0.22

[ particle-01 ]
mass = 255
position = -2.3, -1.11, -0.22

[ particle-02 ]
mass = 224
position = 2.3, 1.11, -0.22

[ particle-03 ]
mass = 224
position = 2.3, -1.11, -0.22

[thelusiv]

Which car on the vamos site are you using? What car in VDrift are you adding these values to?

[osiris]

I don't know for Vamos but in Vdrift, it's the G4(ratios are the same, torque is stronger, better tires, other brakes, 6500 RPM instead of 7000, stronger rear lift are my changes)
This topic is about tires :
http://vdrift.net/Forum/viewtopic.php?t=441
I will seek more info next week.