Uploaded January 2018 | Updated September 2026, 10 hours ago

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We are currently working on a new feature for Blender Fracture Modifier called Multipass. Multipass basically splits a large rigid body simulation into smaller separate ones depending on a user defined hierarchy. This reduces not only the required total processing power but this way the system can even utilize multiple cores of the CPU making much larger global simulations possible.

Of course, there are some disadvantages to this method too. For instance there is only one-way interaction between different hierarchy levels possible, meaning that the concrete can push the windows away but not the other way around. Also there is no interaction between objects on the same hierarchy level other than the first one possible, like one window can't collide with another window. However, for a use case like this building these limitations aren't really noticeable.

The performance increase here is not ideal as it depends a bit on the specific scene, since the first hierarchy level is not parallelized as I want two-way interaction between objects there. Also in this case I have included only a few second level objects which will benefit the most from it. When the building is complete and the computation time of higher levels increases then it becomes more efficient.

Each subsimulation is cached into an external Alembic file which helps keeping the Blender scene more manageable. As a side effect these files can also be used outside of Blender in your favorite proprietary software. In theory you could even simulate the windows or furniture again without resimulating the entire building from scratch.

That's it for now. I'll show you the full building next time, so stay tuned!