Hello people and a good day to the lovely and nice devs!
I encountered the multiple root problem and I may have a solution.
I made a LOT of tests and here are the things I expierienced:
Using my mesh or any combination of premade models from Softimage (inclusive rigs) resulted in arbitrary import problems. In fact it was completely illogical. On the first try all things were OK. On the second try all things were messed up.
The importer doesn´t care about, if you create random nulls in your hierarchy or create a long list of parent/child nulls.
Putting the mesh/meshes under any place in your hierarchy won´t change anything.
Regarding the settings in the FBX exporter:
You don´t need to turn on Ascii format. It makes your filesize bigger, but it doesn´t change anything.
You don´t have to turn on selection only. If you have multiple meshes or anything other than cameras and lights floating around in the scene root, you probably should turn this on to be on the safe side. If you only have cameras and lights in your scene root, go under the setting “Include” and take the ticks out of the checkboxes “Cameras” and “Lights”.
If you have an animation, tick “Fcurve”, “Shape” and “Envelope”. Before you even try to export an animation, be sure to have plotted your animation. Else it won´t move an inch in U4.
Now to my solution:
Export your model/animation/whatever as a fbx.
Import your exported FBX into Softimage into a new scene.
Export your imported model now the second time and you should be good to go!
My thougts on this issue:
I think the U4 fbx importer gets confused, because softimage uses a different kind of settings regarding roots and bones. When you import your model the second time, you will notice that your bones are now nulls. Because nulls are the smallest/simplest unit regarding animation and rigging, they can be interpreted better from U4´s FBX importer.
I hope you can use my advice :).
PS: You are Epic, Epic games :D. (Oh that was a terrible pun…)
On first try I didn’t encounter any of the problems you mentioned, nor with static or skeletal meshes, the only thing that I had to do ( right now is deault ) is to tick “Import bone in hierarchy” when using skeletal meshes ( check my signature for the video )
I did tick the option, because I´ve read it elsewhere on the unreal forum. But it didn´t matter. It always complained about multiple roots and like I said it was completely arbitrary, regardless what I did. If nobody else encounters the problem, then I am happy :). It was very frustrating and took a very long time to solve :D.
We don’t support multiple root and as you mentioned, we don’t handle null groups. We only consider mesh and we do import null groups within bone hierarchy but I suppose problems can happen if it’s outside of bone hierarchy.
If you’d like to provide FBX that you think it should have worked within this condition, please send us the file. Check this link for how to send us the FBX file.
Thank your for your kind answer and I apologize for my late response.
I found out that even the stock rigs from softimage didn´t work. I build a new one from scratch and I don´t get any error. I also noticed some strange behaviour. When I animated my characters in softimage, all things went well. When I imported it into U4, then it wouldn´t apply any animation on my skeletal mesh. It was the same with the stock rigs + meshes from Softimage. No animation.
Now I found out the culprit: Believe it or not, when you duplicate a bone you created, IT WILL BREAK THE ANIMATIONS ON THESE BONES! The workaround is just creating bones from scratch in Softimage. It might have to do with the FBX exporter from softimage, giving U4 some weird info about duplicated bones. I tested it and it works that way :).