I am trying to create a building collapse simulation using FM 2.79, but I don’t know how to constrain multiple objects together at once. The constraints seem like they’re for individual fractured objects.
You can use the “regular” constraints and the connect operator (like with regular rigidbodies) for 2 fractured objects or for 1 fractured and one regular rigidbody as well. But note, this only works to a limited extent, because each regular constraint can only bind one shard of one object to one shard of the other object basically. You can additionally use the “inner” constraints in each FM object to make it more stable. But in most cases you might need a couple of regular constraints at slightly different locations between 2 fractured objects in order to successfully connect more shards across the both objects.
Another way (but also clumsy) is to either join the fractured objects (only one fracture setting then possible) or attempt to use subobject groups, but this has been more like an attempt to get around external constraints.
In this case, I need to connect the 5 beams, plus the floor slabs, meaning it’s more than 2 constraints.
As Scorpion said, try to join all the objects of the building into one object, add FM with enabled “Split Shards to Islands” and “Use Constraints” settings and you are good to go.
To fix the foundation create a vertex group on it and add it to the Passive Vertex Group option under Advanced Fracture Settings.
Change Search Radius to increase or decrease allowed constraint length between shards, Threshold for breaking thresholds etc.
Thanks for that. Though with higher shards, random extrusions or holes appear in compound structures (if using objects with different shapes)