Friction sound

note173 · **Joined:** Wed Jan 25, 2012 6:32 pm **Posts:** 16

I've managed to do simple contact sound effects (iterating over contact points every simulation tick and taking m_appliedImulse). But how can I implement friction sound (e.g. when vehicle tires slide or a crate being dragged)?

kloplop321 · **Joined:** Sun Jan 01, 2012 7:37 pm **Posts:** 55

I think the source engine detects a dragging motion, and then periodically checks if its still dragging or not, so its not a continuous detection, but only once every 200ms or so.

marios · **Joined:** Mon Jul 19, 2010 3:11 am **Posts:** 49

I have implemented basic physical sounds effects (impact, scratching), You can find mini tutorial here http://szamq.wordpress.com/2011/09/18/physical-sound/ The frictional sound method is done in the same way like yours - iterating over contacts, but with different condition

note173 · **Joined:** Wed Jan 25, 2012 6:32 pm **Posts:** 16

Thank you, it gave me a direction to think on.

And how do you handle rolling objects? They may have opposite velocities, but every contact point will be fixed in objects' local space (if there is no slipping).

marios · **Joined:** Mon Jul 19, 2010 3:11 am **Posts:** 49

i haven't implement rolling sound jet, but i believe it can be done like other two sounds by adding another condition which compares angular velocity of two objects body->getAngularVelocity(). Like this:

Code:

if(enough impulse and penetration) impact_sound();
else if(contact point distance < small value && linear velocities difference > small value 2)
{
   if(angular velocities difference < some value) rollingSound();
   else slidingSound();
}

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Friction sound

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