[ODE] Racing game settings (update)

[Alex Amsel]

Spent my evenings on this now (another full time project during the 
day... busy old me).

Got a half decent car set up now that plays quite nicely, but have a 
few generally queries and notes for others.

The 0.04 slip2 doesn't work for me - to do with my masses/sizes? No 
bother as I've found a good range of values. I'm not sure this is the 
best tyre friction model (its ok, but not more than that) so may 
check out the alternatives. Has anyone integrated another one into 
ode yet?

When setting slip2 I have the option of using the angular vel of the 
wheel or the vel of the chassis in the forward direction or the 
overall vel of the chassis. I was guessing that (even allowing for 
wheel slip) that I should use the angular vel of the wheel in the 
axis2 direction, except I'm not sure how to calc linear or angular 
vel in a particular axis (I mul'ed the vel and normalised axis2 axis 
but that ain't right).

The only other real issue I had, and still have, is slight variations 
in the front wheel direction cause slight steering issues when the 
wheels should be straight. I did a lot of testing and tried a lot of 
things, but ode can't seem to keep within a limit of 0 / my fixes 
have the same problem. Some scenes are worse than others but I do get 
the prob even on a flat floor. It looks like the motor on axis2 (with 
a preset target vel and throttle-linked torque) is the problem. It is 
less apparent with foot off the gas. Ideas?

Changing erp etc values didn't fix the problem tho maybe I just 
didn't try the right values.

For those with problems of car tip etc - I've think I've got all 
those sorted and even the suspension works nicely (handbrake gives 
funny results!). I'm also lowering the mass and pushing down on the 
car when relevant - had to do a couple of bodges due to the varied 
environments - i.e. only push down if 2+ wheels on the ground and at 
least one of the front wheels (otherwise it dropped to quickly on 
ledges causing flips).

Perhaps we should create a document for ODE-implemented car physics 
as there is so much different information often only relevant to 
certain setups.

Alex Amsel 
Tuna Technologies Ltd (Sheffield, UK)
PC/Console Game Development
Tel: +44 (0)114 266 2211  Mob: +44(0)7771 524 632