Sparking effect when karts touch each other or metal objects

[suiciwd]

Having a spark effect when metal touches metal (and also having a metal rubbing metal sound) would be a nice graphical addition to our game.But it should only happen if a kart touches metal or another kart , not if it touches a wooden tree or something.For wooden objects like trees we should have a particle dust effect a wood rubbing sound to simulate wood dust (I don't know how GPU / VRAM intensive this is though)

There should be more sparks if the kart is moving faster against the rubbing object and less sparks if it is moving slowly against it and same thing for the wood dust so it won't look ugly and fake .

[Arthur]

I think this could be achieved by extending our particle system. Not high priority obviously but if someone finds the time I agree it might look nice.