Exporting Geometry Collections into UE5

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Joined: Oct. 2018
I’m looking into exporting pre-fractured meshes from Houdini into UE5 as a Geometry Collection.

I’d like to use the RBD Material Fracture node to create 3 levels of fractures – Let’s say there’s a sphere that gets fractured in two pieces (L1), then those two get further divided into two (L2) and then each of those 4 pieces gets divided into two once more, to a total of 8 (L3).

This works in UE5 only up to level 2, but not with level 3.

Here’s my level 2 setup (also attached as an HDA), I’m using a combination of @unreal_gc_pieceand @unreal_gc_cluster:
  1. All primitives get @unreal_gc_cluster = 2to indicate 2 levels of fractures
  2. Then selecting primitives by their @namenotation that’s coming from the RBD fracture, I divide them into two clusters:
    @name=piece0-0-*get assigned @unreal_gc_cluster = 1;@name=piece0-1-*get assigned @unreal_gc_cluster = 2;

    However, I am unable to do this with the level 3 fracture, as the primitives need to be in multiple clusters at the same time and that doesn't seem to be possible with the current attributes.

    This is the level 3 setup I’d like to achieve in UE5, where I had to cluster the leaf nodes manually:

    The provided example HDAs show multiple levels of fractures, but never with the hierarchy that I'm after, where clusters would split into smaller and smaller chunks.

    The documentation [www.sidefx.com] says that "Full control over the exact GeometryCollection hierarchy is not supported at this time", is this one of those cases or am I doing something wrong? If it's the former, do you have a timeline when this could be implemented?


GC_Houdini_01.jpg (224.6 KB)
GC_Houdini_02.jpg (232.7 KB)
GC_UE5_Desired.jpg (217.5 KB)
GC_example.hda (61.1 KB)

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