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4.13 imported UCX collision broken

Build Type: 'Binary' build from the Unreal Launcher

Build version: 4.13

Detailed description of the issue: Testing collisions in the UE4 first person shooter sample project, the same .fbx with appropriately named UCX collision mesh (ie MyMesh and UCX_MyMesh exported as MyMesh.fbx) that works in 4.12.5 imports into 4.13 with a random number and configuration of missing or stretched collision geometry. Happening 100% of the time, although consecutive fresh imports and reimports of the same file results in a different set of missing or warped geometry. Collisions are simple sub-object cubes stacked end to end, normals are all facing outward, collision cubes are fully enclosed, no concave areas, geometry is not intersecting, and again, the same collision objects import correctly and function correctly in 4.12.5.

ETA: Uploaded .fbx as per Tim's instructions (thank you!)

same .fbx in both versions

[1]: /storage/temp/108137-testcollision1.zip

Product Version: UE 4.13
collisionerror.png (568.2 kB)
testcollision1.zip (37.0 kB)
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asked Sep 22 '16 at 02:09 AM in Bug Reports

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avatar image Tim Hobson ♦♦ STAFF Sep 22 '16 at 07:45 PM

Hey Laurie,

I've tried to reproduce but not seeing the same thing on my end. When you try to attach the FBX make sure it's in a .zip folder to attach it. The file attach is finicky and will only accept some file types.



avatar image LaurieAnnis Sep 22 '16 at 08:39 PM

Thank you. Uploaded the offending .fbx in a .zip file format.

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Thanks for posting the FBX, Laurie! This appears to be an issue with 4.13 but not in the latest 4.14 internal build that I have. Looks like this has been fixed internally even though I couldn't find a ticket that referenced it in our system.

This should be fixed in the next major release. If you need these collision boxes it may be worth importing into an older release like 4.12 and migrating or sticking with 4.12 until this is resolved.


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answered Sep 23 '16 at 03:27 PM

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Tim Hobson ♦♦ STAFF
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avatar image LaurieAnnis Sep 23 '16 at 08:30 PM

Thank you! Will do then. I discovered the issue after trying desperately to hunt it down in the modeling software, somehow forgetting that I updated my engine version.

avatar image SE_JonF Oct 20 '16 at 11:09 PM

I just came across this issue. Good to know it's being resolved. Hopefully migration will prove to be a sufficient workaround. Can't imagine delaying a product release until 4.14. =/

avatar image Spiris Nov 04 '16 at 10:51 PM

Is there any chance of getting a source fix for this or a 4.13.3 release with this fixed? It seems like too much of a gaping hole in the asset pipeline to leave untended until 4.14 is released with no guarantee of other holes not being punched on that release.

avatar image Waqas Nov 25 '16 at 12:18 PM

Hi, I am still getting issues when importing UCX custom collision into Unreal 4.14. where the faces of the mesh seems to be randomly collapsed and/or missing altogether. My scene was initially imported from Revit straight into 3D MAX which made it appear around 1,5 km from the origin. My initial export of objects and Collision meshes seemed perfectly fine. When I got to to modelling collision for the stairs with slopes, it turned messy. As an experiment I moved the stair mesh to the scene origin and that seemed to fix the distortion issues with UCX meshes. I don't know what is happening under the hood of Unreal engine, but it seems that UCX meshes have lower accuracy than render meshes?

avatar image Tim Hobson ♦♦ STAFF Nov 28 '16 at 03:59 PM


Using the test asset provided in the OP works as intended by importing the custom collision. This was broken with 4.13 with some meshes it would seem. It would probably be better to post a new question with a test asset and details to reproduce the issue.

Thank you!


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