How to copy an objects between multiple physics world?

[drawtree]

Hello.

I am making a game which needs replay feature. The replay can be recorded from any specific time point during playing game.

I think it's possible to implement this by capturing and reproducing the whole physics world state, (this can be limited to only some objects) and continuing physical with external user input.

But it's hard to figure out how to capture and reproduce physics state *completely*. I can copy position and torque, but it doesn't seem to be enough to reproduce whole physics state.

What should I copy to completely reproduce physics state? For a single object, multiple object or whole physics world.