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bkohrman
I'm currently fracturing meshes that were built in other programs. What is the best way to have the fracture NOT separate the original mesh into it's component pieces? For example, if I fracture a wooden door made up of separate planks, how can I break it only along the voronoi fracture lines, and NOT break the individual planks apart?

This is important because UE4 interprets a mesh fractured in this way as way too many pieces for my needs. If you use an exploded view node, you'll see exactly what I mean. UE4 explodes the mesh in the same way.

One way I have gone about this is to do my initial fracture, then add a cluster attribute to the primitives. I then run a for each loop over each cluster, and that booleans/unions the pieces in each cluster together (with another for each loop, running over each piece), then I change the name attribute on each primitive to be the same per cluster. It felt clunky, but it worked. UE4 interpreted my new clusters as connected chunks.

Is there a better way to do this? I feel like there should be a checkbox in the Voronoi Fracture node that asks whether or not to split up the original mesh along it's own seams.

I'm using Houdini 16.0.

Thank you!
bkohrman
I was watching this video from GDC last year about Booleans:
https://vimeo.com/228248086 [vimeo.com]

I discovered I can union a bunch of geometry together WITHOUT all the for loops. Just plug your merged geometry into the boolean, and select “Union”. Well, that makes it a lot easier! But I'm sure all of you already knew that…
mikelyndon-sesi
If you're using voronoi fracture you generally want to run it over each piece separately. Otherwise you can get some weird results.

To control what gets output to ue4 it's all about the geometry containers that you use to separate pieces before exporting to fbx. If you use the name attribute generated by the voronoi fracture you can use that to isolate each voronoi cut regardless of the plank separation.

I don't know if that makes sense but focus on the exporting stage.

Mike
bkohrman
Thank you, Mike! I was able to get this working. For my simple fracture test:

1) I made 4 boxes in the shape of wooden fence posts and merged them.
2) I scattered points on the fence, and I added an i@cluster attribute to each point that was equal to @ptnum.
(My code in the point wrangle: “i@cluster = @ptnum;”)
3) I used those points to fracture the merged fence mesh, and transferred the cluster attribute to the primitives using the voronoi node.
4) I changed each primitive's name to be the same for each cluster.
(My code in the prim wrangle: “s@name = ”piece“ + itoa(i@cluster);”)

I then used the Static Fracture Mesh tool on the final node using the Piece Name export mode, and exported an FBX. It worked perfectly in UE4. Thank you again for the help!

NOTE: I did NOT used packed geometry. I wasn't able to get the packed geometry method working yet.
Ademir
I'm having the same issue, would you mind posting your hip file if you still have it? I'm new to Houdini so your explanation isn't enough. Thank you
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