initial collision detection

[GameQ]

I have read the wiki and found a few posts here about how to detects collisions from Bullet. I am unfortunately not finding much info regarding the detection of initial collisions between objects.

I am currently looping through all the Persistent Manifolds from the dispatcher. I know I could use btGhostObject, but I'm actually am looking for all collisions so that I can call per object onContact functions, and then the object can handle the collision as the programmer sees fit.

I want to also have an onInitialContact() function that gets called once and only once per collision. This would be mostly useful for sound playback. If a ball hits the floor, play a "dink" sound. But in my current implementation that sound is fired off every frame, cause the ball may hit the floor and the start rolling on it.

I know that manifolds are persistent. Thus the manifold will still be in the list even after the objects separate. I resolved this problem by simply testing if there are any contact points.

Code: Select all

//psuedo code
for(all manifolds in dispatcher)
{
   if(initial collision) //this is what i need help with defining
   {
      objA->getUserPointer()->onInitialContact(objB);
      objB->getUserPointer()->onInitialContact(objA);
   }

   if(manifold->getNumContactPoints() > 0)
   {
      objA->getUserPointer()->onContact(objB);
      objB->getUserPointer()->onContact(objA);
   }
}

Thanks for any all help,
~GameQ