I'm currently detecting contact between bodies (for playing sounds, etc.) by iterating contact manifolds as suggested in the wiki:
http://bulletphysics.org/mediawiki-1.5. ... d_Triggers
When a new contact manifold is added (with suitable contact points) I run my contact handling code for the two bodies. This works well for falling and bouncing bodies, but I get no contacts in case of a rolling cube (pushed by player). I assume that this happens because the the cube and floor are continuously in contact, so only the contact point count within manifold changes.
I first though of checking whether the number of contact points in manifold has increased since the last update, but I don't know which of the contact points are new.
How have other people solved this problem?