Most physics engines used in software like Blender, Unity, or Unreal Engine provide APIs or scripting interfaces that allow you to access information about constraints in your simulation. You'll want to familiarize yourself with the documentation for the specific software you're using to understand how to access constraint information programmatically. Official Website
If you're working with packed geometry in your RBD simulation, you'll need to iterate through each packed piece to access its associated constraints. Packed geometry typically represents multiple pieces of geometry as a single entity for optimization purposes.
Once you've accessed the constraints connected to each packed piece, you can count the number of constraints associated with each piece. This could involve iterating through the constraints and checking which ones are connected to the current piece.
As the simulation progresses, you'll want to continuously monitor the status of the constraints connected to each piece. This could involve regularly updating the count of constraints associated with each piece and taking action when a piece breaks free of all constraints.
When a piece breaks free of all constraints, you can apply forces or other effects to simulate the behavior of the broken piece. This could involve applying impulses, adding forces like gravity or wind, or triggering specific events based on the piece's status.
