# Joint based destructible physics (like Armadillo Run)

I've implemented a destructible terrain system like Worms before (where weapons create holes in the terrain), but for the game I'm designing I want something more like Armadillo Run: https://www.youtube.com/watch?v=4JoPlcyxxb4 where everything is made from individual parts connected by physics joints.

I've figured out how to make a chain of planks using Unity's joints that can fall, swing off each other, bend if unsupported, and break at the joints. But I can't think of how to make planks break instead of the joints. There's an example of what I want at 2:25 in the video, where the plank on the right breaks (not the joints, but the actual plank itself). Obviously I'd just have to destroy the plank object, but how do I decide when to do that?

I'm using the Unity engine (2D physics), but I'd be perfectly happy to implement something myself if someone can direct me to some research on the subject or anything else to help me get started.

Keep a list of all your joints and store their current reaction force (GetReactionForce) with each update.