Unity 5 - Wheelcollider wrong rotation

Unity Engine
1

Hello Unity.

Some time ago I posted a question about the unity 5 wheel colliders sinking into the ground.
I concluded that it must’ve been the rotation of the wheel collider that just looked outright wrong. I got my theory confirmed when I saw this posted on twitter: https://pbs.twimg.com/media/CAx-5OkWwAA0I18.jpg:large

You can see how my colliders looked when I asked the question back then:

Here’s mine now, after some deleting, editing and adding again:

874×488 219 KB

What is seriously going on? Now it’s rotated on a really special angle. I swear, I did not do anything that could’ve made it rotate on that angle.

The more I mess about with these colliders, the more problems I get.

-Thanks.

2

Hi Mads232, For starting I use this Unity free tools included with Unity 5

I use the car as starting game object.
It is not the answer you are looking for but can takes out of the problem fast.

3

I saw a comment that a wheel colliders up is based on rigidbody up.

Them some odd angles you got though. Are they the scene view? (As in not playing)

4

WheelColliders always point in the “forward” and “down” direction as the rigidbody they’re attached to. The steerAngle value is relative to the rigidbody’s forward direction.

2 Likes
5

Thank you for your suggestions and answers.

JamesLeeNZ yes this is in scene view. I do have some weird rotations from blender but as it is of now, the parent object’s rotation is 0,0,0. :slight_smile:

6

Wait, maybe there’s still some rotation issues that may make Unity think that the rigidbody’s up is not my forklift’s up? I’ll check that out later

7

Also, can center of mass do such a thing?

8

Are all your rotations 0,0,0 when not in play? You mention your parent, what about the rest? Ideally you will have 0 rotations for everything, including children. Ensuring that will make your life hella easier. Also make sure your pivots are centered, mainly for the wheels.

I dont believe COM will cause your particular issue.

9

Thank you for your reply. Not all things are 0,0,0. For example the forks are rotated 270. It’s been a pain in the *** to get it as it is now. The wheelcolliders are attached to a new gameObject which is placed at the wheel’s center

10

its more of a pain in the ass to work with non uniform angles imo. I know its easy to reset the pivots in 3dsmax. I assume it aint too difficult in blender. I would recommend the first thing you do is sort that out.

11

You’re god damn right. The thing is, Blender’s Y and Z axises are switched. I’ll try but it might take a while before I’m able to, so I’m still open for suggestions.

12

Its the same in 3ds max. If you reset the pivot, the default imported fxb will have a rotation of 90,0,0. The thing is, you can usually select all objects, reset, rotate, done. Its not hard once you figure it out.

Why might it take a while before youre able to? youll probably save yourself a massive headache if you can.

Incidentally, you can actually edit fxb files in Visual studio (surprisingly). Might have to be 2013 for it to work. I havnt tried resetting pivots using it, but I think you probably can (tbh I was just surprised when it opened)

13

I know what I have to do, no worries. :slight_smile: It’s just that I’m busy this week so it might take a while before I’m able to.

14

heh all good. I end up resetting pivots a lot in models, so at some point teach yourself how to do it quickly, because its something you’re probably gonna end up doing a lot

15

You might try this this Blender To Unity importer.

I’ve been told that a recent version of Blender has a new experimental option at the FBX exporter that resets some transforms before exporting. I haven’t tried, so I can’t tell for sure if/how that would work.

16

Thank you for your reply! So does your script also have the ability to fix the rotation with .blend files? I really wanna be able to use the blend files, which I just find very useful.

I think my solution will be to rotate the entire thing 90 degrees. :slight_smile:

17

My script fixes the rotations so when you set 0 degrees in Blender, it results in 0 degrees in Unity. Other angles are translated properly so the model in Unity looks exactly as it was designed in Blender.

18

Yes I am aware of that, but does this is only work when I export it as fbx or can I use the .blend file? I don’t export to fbx

19

So I tried turning the forklift -90 degrees in blender, which it did not like:

846×473 410 KB

Although by dragging in just the prefab I got the result I wanted. I’m going to try and copy all of the scripts, colliders and everything over to the new one I just created. Then I’ll see what the result will be.

20

Now, this looks promising! The wheel colliders looks like they should now.