Proximity Query - proper method?

[Spaddlewit]

I want to do an ad-hoc query for collision objects that are X distance away from a btVector3 point. What's the best way to go about doing this?

[MaxDZ8]

If you want to do it continuously (ie. each frame), using a Ghost Object is likely the way to go.
To produce the results on a limited frequency, it is possible to create an ad-hoc rigid body and run btCollisionWorld::contactTest. You don't even need to add the sensor object to the world, it's very convenient.