In the previously session we skip the "contact event" attribute of RBD emitter because we have to talk about some new concept on collision and collision query.
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Instead of letting the agents query collision with RBD from emitters, we make an inverse perception. We designed letting the RBD query collision with agents, and if collide, it will tell the agents and automatically hold there.
We introduce rbdCollide channel, this channel will return value bigger than 1 if the RBD objects from emitter hit the agent body part. It's not agent query collision from RBD objects, it's these contact objects tell the agent, so we call it inverse perception.
And this channel only work when we set to 
mode for the RBD emitter.
Firstly, the RBD objects will hold on whatever it contact if set to contact
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This time the hold RBD object will tell the agent, "I contact you" and the rbdContact channel will be true, then you can enable the dynamics for the agent
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A simple arrows rain example scene
Contact and Delete
If we switch the contact event to "delete", the rigid body which emitted from rbd emitter will be remove after contact with anything. And if we used the rbdCollide channel, it will tell the agent it contacted with that agent. This can easily simulate the gun fighter like laser gun scene.
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