Can you limit physical materials to certain meshes?

What i want to do: I want to place an office chair on a floor, but have wheels on bottom of mesh have a slight negative “friction value”. So when chair is standing up, it will slide more easily when collided with. I haven’t found any workaround yet and an answer would be much appreciated. My initial thoughts where to apply a physical material to just wheels or apply it to floor and have all other objects ignore physical material, but i haven’t had any succes. Maybe someone knows how to get either one of theese solutions working or they have one of their own. Sorry for bad english.

Hey fluzzy,

Applying a physical material with a negative Friction value onto wheels ought to work. What isn’t working specifically? Does your chair move at all when pushed? Do you have Simulate Physics enabled on your chair mesh? Is its collision set to PhysicsActor?

Yes, chair moves, but when i apply Physical material to floor, I get desired result, but it applies to all of my objects on that surface. When i add it to wheels ( wheels are not a seperate mesh but they have a seperate material) it doesn’t seem to affect it at all. Do i need to have wheels as a seperate mesh and then combine it with chair mesh in unreal?

:confused: I applied same phys material to a box mesh just now aswell and that worked fine, maybe unreal cant identify where material is applied since collision is powered by (in my case) auto generated collision mesh? Just a thought, I did exactly same thing with box as with chair and tried them both at same time. Box works, chair doesn’t.

forum said I couldn’t send file here, invalid file format or something. So a dropbox link will have to do. It’s a prototype so i might have messed up somewhere but I honestly don’t know where.

That shouldn’t make a difference. I just tested it on a simple box and it worked fine. It may seem silly, but try saving physical material, material, and level, and then try. It’s possible Friction setting just hasn’t taken effect yet.

Hm, no, collision shouldn’t be causing this. It might have something to do with how your Material sits on your mesh. Would you mind attaching your chair .uasset? I’d like to take a look at it and see if I can’t figure out what’s going on. Thanks!

Hey fluzzy,

I took a look at your mesh and I’m seeing same thing. It looks like only way to have a physical material affect way mesh interacts with other actors is to have it in Element 0, which affects entirety of mesh instead of just material in that position.

I’m checking with developers to see if this is intended and if there are any workarounds. In meantime, your best option (assuming you don’t want entire chair to look like it’s rolling around rather than just when it’s upright) is going to be separating wheels from rest of chair as a second mesh and attaching it to chair body in Scene Outliner, as you suggested earlier.

Sorry for inconvenience. I will let you know as soon as I find something out.

Splitting meshes and using a Physics Constraint Actor works perfectly, I will probably stick with this solution as it enables top part of now remodeled chair to rotate like it would in real life. I would however be incredibly grateful if you could update me on original question if you come across a workaround as I (and others) might run in to same problem but in other scenarios. And if it matters, I would just like to say that this is probably best company/client interaction I have ever witnessed! Big ups to you and Epic!