Fracture modifier to only fracture surface of object

I’m trying to achieve a similar effect to this where only the surface of an object flakes off like embers floating off burnt skin. Is this possible in the fracture modifier build? I’ve had a good look and couldn’t find anything.

Hi, you could use Fracture Modifier’s “Voronoi + Bisect” which does not generate inner geometry when fracturing and solidify it or alternatively use a solidify modifier before the Fracture Modifier (and use either “Voronoi + Boolean” or “Voronoi + Bisect + Fill”) to fracture. Or if you just want to have a thin surface, do not use the solidify modifier here :slight_smile:

Hi Scorpion81,

I managed to create and fracture a thin layer around the object by using a solidify modifier and filling the rim before the fracture modifier and using ‘veroni+Bisect’, thanks for your help!

I’d like to have only 3 or 4 out of 100 small pieces slowly flake off and float away over time while the rest stays intact (a little more subtle than this image above) but I’ve played about with it and can’t get the other pieces to stay put.

Also as I’m new to the Fracture Modifier build, is it safe to do the rest of the project in it or is it best to only do fracturing sims, convert to keyframes and open in the main build to continue work?

One more question, I couldn’t get adaptive subdivision/microdisplacement to work on the fractured object, is this a limitation, or am I doing something wrong?

Thanks again for your help,


Quick test…

Hmm to activate only certain shards, you could make the fractured object animated and triggered, and let the parts which you want to have activated be “touched” by another rigidbody which is a trigger, optionally that trigger can also be a ghost (so only activation happens but no collision with the trigger).
Using forcefields will affect the active shards as well, you need to play around with forcefield strength and / or mass of the object. Note, that the mass is distributed across the shards according to volume fraction of shard compared to total object volume.

Whether to stay in the FM build for the entire project or using the official (or even daily / master build) depends whether you need newer (master) features or how frequently you need to alter the FM sim (would require lotsa rebakes if you keep tweaking). But otoh it could be more render-farm safe to convert the shards to keyframed objects. In case you need special FM features like autohide or automerge you would of course need to keep in the FM build. Alternatively you also could export the FM simulation via alembic and re-import it to blender. (you get a single animated mesh then, but this can take changing topology into account as well).

Hm regarding microdisplacement, in general it should work if you have the adaptive subdiv modifier after the FM and to get around edge discontinuities in microdisplacement, you might need smooth shading (refracture after switching object to smooth) and need to use autohide and automerge distances slightly above 0 (arount 0.001 or so, each) and optionally “Perform Merge”, so “cracks” on the surface disappear. Smooth works a bit around the general limitation, that we have discontinuities in the shader result at sharp edges.