There are many ways to implement a physics based explosion. With Bullet Physics there is such thing as btPairCachingGhostObject. Another option is to use contactTest queries. Here’s a discussion thread about these methods.
In our game we’ve used a much simpler method: inserting a physics sphere with double radius and then removing it from the scene after 100 milliseconds. This gives necessary impulse to all overlapping our sphere objects without any additional calculations.
Senior Software Engineer developing all kinds of stuff.