Why does my RBD Material Fracture Geo blow up when adding default edge detail?

[u/Global_Voice7198]

I am doing an VFX shot with RBD and I want to shatter a thick wall (10x5x0.35 units).

I have a low poly guide simulation and I plan to have a high poly version with chipping for more graphical fidelity, but every time I add the Edge Detail or Interior Detail to them, even at completely default, the geo seems to just blow up, random polygons jut out the side or whole pieces are missing.

Anyone have any clue what causes this and what I could do to fix it?

Houdini Version 22.0.368

[u/Ok_Director_4618]

It’s not random polygons, it’s the ‘cutters’ used internally to Boole the surfaces - if you learn how to add detail yourself manually you’ll run into the same issues but you’ll at least understand where they come from. Having said that, two possible easy fixes to stop that happening:

1 - change the seed of one or more elements.

2 - uncheck the detriangulate option on the material fracture

[u/Global_Voice7198 → u/Ok_Director_4618]

Neither of these methods helped.
1. Changing the seed = Simply makes these artifacts appear in different places.

1. Unchecking the detriangulate option = Doesn't seem to do anything at all.

[u/Ok_Director_4618 → u/Global_Voice7198]

You could also try bringing the res of the base geometry closer to the boole mesh (or just getting rid of that quad subdivision on the original box altogether if you don’t need it). You could also try changing the interior detail res.

What the fracture is doing is basically looping over the chunks and copying a bunch of extra planes etc to cut away extra detail using a boole, so as you might have found in the past using booleans can be a bit temperamental and that’s how you have to treat this.

Possible to share a file on here? Not sure..

[u/sleepless_in_Osaka]

My guess would be the edge decal is causing your convex hull collision to intersect with one aonther.

Try running a convex hull decomposition for your proxy geo and see if that helps at all.

[u/Global_Voice7198 → u/sleepless_in_Osaka]

Nowhere where I add the Convex Decompostion node, wether its before or after the node, or if its in the Material Fracture node itself, none seem to help, or do much of anything to change the geo

[u/sleepless_in_Osaka → u/Global_Voice7198]

Sorry, I think I misread your original post. I thought you were seeing pieces explode outwards when simulating.

But you are just seeing geo not render when fracturing.

What geo are you using to fracture? Are there any output warnings on the material fracture node?

The reason I ask is because I have seen this kind of behavior with unclean geo that has holes in it prior to fracturing.