We have been suffering from a problem that happened in Vehicle system in Unreal Engine. Approximately more than a month ago I posted a question to answerhub. The link is:
Thanks to , he tried to help us, he solved the and posted working vehicle system in asset files to hub. But still we cannot make our own models work in Unreal. As I understand, he is well experienced in 3ds max but not in maya. Unfortunately our designers work in Maya and we couldnât solve the problem.
Iâm gonna paste the text from answerhub directly to above.
We tried every possibility in export options in Maya and import options in Unreal. Nothing has changed. I know most of the people are using Maya just like us, I think problem could not be related to Maya-Unreal incompatibility, both of the softwares are well-known and widely used by community.
Weird thing is that, when we get some working model from somewhere, import it to Maya and re-export it to Unreal without changes, still could not get a proper working vehicle.
My question is for Maya users, did you experience such problems? Also any comment, any idea would be precious as like diamond for us, we stucked and cannot go further.
I used same blueprint, vehicle blueprint, game mode etc. with 's posted one, Iâm quite sure the problem is not caused due to wheel blueprints. Just like I said in my previous post, we get a working vehicle fbx model from internet, after importing it to Unreal, it works as expected. But if we put it to maya, without any changes export-import to Unreal again, -without any changes-, result become as in the video.
Looking at image in your video, the Box collision on the root bone (body) is extending down too far, you donât want the box to be any lower than the underside of the car. Try adjusting it and see if it helps.
Thank you for your answer, but we have already tried to get root collision to be realistic like, down-z position starts from carâs body, neither zero position nor wheel positions. Iâm afraid its not the solution. The weird thing is that, Unreal only detects body(root) collision which means that box you mentioned. It does not recognize wheel collision âif we link wheels to the anim blueprint systemâ, otherwise collisions works perfectly, but as you can guess, vehicle does not move.
Yes that is normal, the wheel collision is not used, but you canât have the main body box collision down that far, it just wonât work. Whatâs happening when you canât move the vehicle is the bodyâs box collision is hitting the ground before the wheels do, not allowing the wheels to move. Here is my working vehicle setup (image 1), if I try and make the box come down to the ground like in the image above, the vehicle wonât move either.
Also in your video when you have a wheel collision cylinder selected, and the Z-axis is pointing in the direction that the Y-axis should be, with the Y-axis pointing downwards. Can you check the rotation of the wheel bones in maya (if you are using bones)? It looks like they are rotated by 90 degrees, try selecting a bone and switch over to rotation mode and check the values to ensure they are all 0.0,0.0,0.0 as has caused problems for others in the past. You can see the difference in the 2 images below, looking at the XYZ axis gizmo, it is pointing in the wrong direction. could also be caused by exporting an FBX with the âY-Axis Upâ, check in the fbx export options when you export from maya and ensure you have it set to âZ-Axis Upâ.
Hope that helps
EDIT: I am also a 3dsMax user, donât really know much when it comes to maya unfortunately so there could be something I am missing, but looking over what had said on Answerhub there must be something going on with X-Form as mentioned, either rotations are off or X_form transformations are causing an, sorry I am not sure how can be fixed in maya, hopefully a maya expert will be able to help here as well.
I just has similar issues over the weekend (I use Cinema 4D), I had to keep changing orientation of my joints until the ended up being imported the right way into UE.
To start with I had to model and rig along the ârightâ axis instead of forward and have my Z pointing down on the joints etc.
Basic mesh/car but it looks like , the key being that then when imported all the axisâ of all the joints match UE world axisâ
That should not be the problem, by the way I forgot to mentioned, we applied reset transform to the model after 's suggestion. And currently skeleton of the model seems like:
Hey man, if you send me a PM with a link to the fbx I can have a look at it in maya & 3ds (and UE4) to see what the is and compare the 2. Iâm not great with maya but I might be able to help find out whatâs going on here.
I still dont have a solution to problem unfortunately. But i watched your video and checked the new FBX myself(i had to pass the file through Max first, delete the bones, reset xform, merge chais meshes and then link wheels to the chasis), and things go nuts the moment i plug the animation BP to the vehicle BP. There was another user(3ds Max time) having sort of last week and it was caused by crazy transforms. Your vehicle should work but i dont know why bones are acting weird with anim BP. Hope can see what we are missing.
It looks like all of the bones are rotated 90 degrees on the X axis (in 3dsmax), in maya it shows 0,0,0 but the co-ordinates are different. In the image below I have only the root bone selected, but the other 4 wheel bones are also rotated the same way.
Try rotating only the bones -90 degrees on the X axis (for each), you might need to remove the skinning first, and will require the car to be re-skinned afterwards as well unfortunately, but it is the only I can see between the 2 programs. I am no good at maya, otherwise I would try it out myself, but would most likely just make things worse.
The car mesh is not one solid object, but I donât think that is an here as the skinning should take care of that, Iâll keep looking to see if I can come up with anything else for you.
, , Anadin, thank you very very much for your helps. We finally got rid of that problem.
Anadin has sent a fbx file that shows the correct way to rotate root bone. We have applied same solution to our model from scratch and it worked. Before exporting the model to Unreal, we gotta rotate root bone in x axis -90 degree. But wheel bones should be the same value with worldâs coordinateâs axis values.
But I must say that itâs really really weird and newbies like us cannot handle with that easily. We have tried every other possibilities by rotating wheels or rotating car completely. I couldnât understand why root bone should have a different axis setup than worldâs axis.
My final worlds, Iâm deeply appreciated for your helps. Thank you
No problem! Great to hear you finally got it working!
I will add info on Maya, as well as other troubleshooting tips for vehicles to a wiki tutorial article in the coming days as there have been a few small issues that have come up recently. As you mention there needs to be a bit more info documented for new users, each program seems to have a slightly different setup procedure. Thank you for letting us know you got it working!
Yeah I am hoping the new transform modifier the importer has in 4.6 will work down the whole heirarchy. That way we can model in our chose DCC âUpâ, âForwardâ and âRightâ and fix it to match UEâs when importing.
Hey guys. Iâve rotated my wheel bones -90, but the problem still happens. Its starting to stress me out and Iâve got all the correct stuff ( Working physics actor, wheel BPâs, Etc) As Iâve worked on my project for a year, it would be a large let down to have to remove one of the biggest aspects in my game. If anybody can help me, it would be deeply appreciated. Iâm using Ue4.14.
Anyway, thanks to all of you 