When generating a Geometry Collection from Fracture Mode > Generate > New > Use Root Proxies (ticked), eventually the GC’s transforms become mismatched.
Found moving the GC once created and then performing a few tasks then undoing caused this issue to occur.
Hello [mention removed]
Thank you for reaching out.
I’ve been trying to replicate your setup here, but I’ve yet to reproduce the behavior you described.
Let me go through the steps I followed so you can let me know what I’m doing wrong:
Hopefully, you can point me in the right direction, for each of these steps could be performed in any number of ways.
I’ll also attach to this reply the repro project I created.
Maybe you would prefer tweaking it so it reproduces the behavior.
I hope to hear from you soon.
All the best,
[mention removed]
Hello,
I would like to shed light on this problem and provide a solution I found on my end. To fully reproduce the issue, the first static mesh selected in the group during GC creation (i.e. the one that will be used as the root node during root proxy transform calculation in the call to FracturedGeometryCollection->SetRootProxiesFromGeometrySources() on line 1013 of FractureToolGenerators.cpp) must possess a rotation. After creating the GC in this manner, you should see the visual pop.
As for the solution I found, I moved the section of code responsible for the root proxy transform generation starting on line 1010 of FractureToolGenerators.cpp to below the call to FracturedGeometryCollection->InvalidateCollection() on line 1025. This was done as the calls to AddSingleRootNodeIfRequired() and FracturedGeometryCollection->InvalidateCollection() directly above may result in the creation of a new root node, which invalidates the previously generated root proxy transforms as they were generated relative to a stale root node whose transform may differ from the new root node’s. Additionally, UGeometryCollectionComponent::RefreshCustomRenderer() uses the new root node’s transform as the component space root transform which will cause the root proxy to be rendered incorrectly if the root proxy transforms are generated prior to generating the new root node.
If you need more information, please let me know.
Thanks,
Jaime P Roque
Hello [mention removed] and [mention removed]
Thank you [mention removed] for the explanation!
Indeed, that was the missing piece of the puzzle!
I was able to reproduce the described issue.
The behavior also reproduces if you spawn the Geometry Collection (GC) by dragging the asset from the Content Browser: the original rotation of the root node is reset, and the whole GC is rotated.
The same happens if you duplicate the GC in the scene by ALT+Dragging the originally rotated one.
If you select the rotated GC and go to FractureMode (Shift+6), the rotation is as expected, but immediately fails again when you are back to SelectionMode (Shift+1).
Thank you for providing your analysis and solution to the problem. That’s really helpful!
I’ll investigate some more, open a JIRA ticket, and ensure your suggestion is included.
I’ll share the public tracking link once I have it.
[mention removed]: As a workaround, for now, I suggest avoiding a rotated root.
All the best,
[mention removed]
Hello [mention removed] and [mention removed]
Thank you again for reporting and taking the time to share your analysis and solution to this issue.
I’ve made a JIRA report at: Unreal Engine Issues and Bug Tracker (UE\-353918)
Please note that it can take some time to be made publicly accessible.
We don’t provide updates on EPS, but if you would like to track the resolution, check the link for the status.
Let me know if I can help you with anything else!
All the best,
[mention removed]