Collision Problem on Vehicle Model-Skeleton Importing From Maya

Development World Creation
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21

What software are you using?

22

Same here. Can’t figure out for Maya. The only way I can get it to work is to export to Max and then to FBX. Maya to UE4 is broken.

23

Fixed it! is how I did it(after trying 42 different things):

  1. Unskin the vehicle and wheels from the bones.
  2. Detach the wheel bones from the root.
  3. Rotate all bones -90 degrees.
  4. Freeze transformations on all bones.
  5. Attach bones to the root and skin like normal.
  6. Export with the Y facing up option with the 2016 plugin version(I don’t know why it needs Y facing up, but it will only work way for me).
  7. Import with the “convert” option checked for FBX in UE4(NOT the extra “force facing x” option).
  8. Profit.
1 Like
25

That weird bug is not consistent, sometime it works the way it is intended to work (no -90, no changing Z to Y on export, etc.). So dont forget to try the normal way, if these workarounds dont help you. Always keep maya project’s save file for that purpose. In UE 4.19.0 bug may appear, or may not appear, so those workaround are not always necessary.

Anyway, thaks for sharing you own workaround.

Update.
VERY IMPORTANT:
Q: How to check if the vehicle model will work as intended or it will bug instead?
A: Very easy to reproduce, just follow simple steps:

  1. Open the Physics Editor (where you did set collisions).
  2. select any joint and switch to the Move gizmo (W hotkey)
  3. in the Phys Editor Viewport’s top click on the “switcher button” to change between local coords vs global coords (the earth globe icon or cube icon), or switch the mode in any other way.
    4.a) in a bugged project the that gizmo will display correct arrow destinations only in global mode, in local it will display wrong directions/wrong arrow colors (Red to Up, Green to Back, and Blue to Left).
    4.b) in non-bagged project it will display right directions (exacly same directions) in both modes, even when you change coord more - you will notice, that arrow dont change directions.

Im gonna officially bug-report it right now.

Upd 2.
reported, will monitor, if it is not rejected. Anyway, if anyone else can reproduce both cases - reply with new post, so i developers will see more evidence

Upd 3.
There is much simplier workaround:

  1. Do the Reimport, in the Reimport window, in the Scene tab, disable the “Force Front X Axis” (Tooltip states as: “… instead of -Y”).
  2. After that open Physics Asset and again “delete everything”,
  3. Again create new collisions for root and wheels (it is necessary to do steps 2 and 3, because those components are bugged, and need to be deleted and replaced with new from scratch)
  4. (optionally) To make sure everything is correct - select the top component in the component panel (Root), enable the the Move gizmo in the Viewport (W hotkey) and then with keyboard’s down arrow you can change selection downwards. You need to make sure, all components are having correct Gizmo Arrow orientations (XYZ/RGB) and that those orientations are same for both local and global, then it will, surely work. Otherwise, it may not work (especially if orientations are wrong for Joints, collisions dont matter as much) and you will need to edit or reimport the FBX file and try again.

If you still get bugged arrow orientations, then you can change that re/import checkbox (“Force X forward”) back Enabled, and try again steps 2, 3 and 4.

It looks, like either that checkbox is bugged, or the FBX importer is bugged, so bug is not consistent.

If you find it helpfull, feel free to update your Vehicle Troubleshooting information, that you mentioned.

Ok, looks, like the only vehicle, that i did not fix - is the official vehicle templates, that drive themselves backwards in circles and without any user input. I have no idea how to fix it. Guess, it may be related to the Reimporting and Axis orientations, but i can not check it, as dont have those original FBX files. Well, at least our custom vehicles will work.

Upd 4:
My bug report was not detailed enough and was rejected, and, i guess, the “Force Front X Axis” works as intended (in case if that FBX file is bugged itself, but if FBX is good, then UE importer is bugged, to ensure it, someone with 3Ds Max needs to check it. I dont have 3Ds Max installed atm, and can not properly check FBX files, so if someone can compare FBX files between Max and Maya, and find out if it is really UE4 importer’s bug - feel free to make an official report, currently i can not fully investigate . The FBX file created with Maya, that i used and with which i had to use different “Force Front X Axis” option’s states for 2 different projects is attached.

26

Holy cow is horrible. Took me almost 24hours to get the import to work.

What i did to fix it:

  • Set the mesh rotation to 0,0,0 to face the right direction (If you notice it has the wrong rotation in the editor, rotate the mesh to the correct rotation, then click “Modify->Freeze Transformations” (maybe only the rotation, click on the box right next to it to change the settings)
  • Redo the rig to fit.
  • Bind Skin
  • Export to FBX with the Settings “Y Facing Up” & 2016/2017 exporter
  • Import in UE with the settings “Force X forward” and the “Convert FBX to UE…” checked.

Should work now.
Like Saah88 said, if you see different directions for the arrows (local / world) in the physics editor, you know your model is wrong imported / bugged.

e/ Also what helped me was to use the command “pxvis collision” - it shows you the phys wheels in editor

Correct (not setup though):

1234×583 137 KB

Wrong:

https://i.imgur.com/0cLYt0m.jpg