elchtest mod :)

[joevenzon]

I have also no idea, what the parameters in setcontact are for. the tread f.e. isn't even used and the road frequency thing also makes only problems.

CAR::SetWheelContactProperties takes these arguments:
* wheel_index: which wheel we're talking about
* wheelheight: {the vector pointing from {the position where the tire patch would touch the road if the suspension were deflected as far as needed to cause the tire to touch the ground} to {the center of the wheel's current position based on the current suspension displacement} } dot product with {the average direction of suspension displacement}
* position: the position where the tire patch would touch the road if the suspension were deflected as far as needed to cause the tire to touch the ground

The rest of the parameters are just surface information about the road object and don't have much to do with the collision itself:

* normal: the surface normal of the road object
* bumpwave: the wavelength of an additional bump surface that displaces the top of the road object
* bumpamp: the amplitude of an additional bump surface that displaces the top of the road object (this and bumpwave are used to simulate bouncy offroad conditions without having to model the bumps with track geometry)
* frict_no: a friction coefficient multiplier to be used with tires that have no tread on this road object
* frict_tread: a friction coefficient multiplier to be used with tires that have tread on this road object (this an frict_no are used to very roughly simulate how tires with a lot of tread don't do well on some surfaces but do well on others, and vice versa)
* roll_res: the rolling resistance of the road object
* roll_drag: the rolling drag of the road object
* surface: the type of surface. This is used to determine what kind of sound to play when driving over the surface.