How do I setup collision to work with the spline tool?

Hello all, how are you today ?

It’s me again and this morning I got some trouble with my road . I use the spline tool with a static mesh (that I create on 3ds max) . The probleme is that I can’t have a collision when this mesh is used as spline (work if I put the mesh as actor on my world) . I try with capped and uncapped mesh :

Then in UE4 I had try “Auto convexe collision” but the result is not good for a race road .
Then I remove all collision then apply a “Use complexe as simple” and my space ship have no collision with the road when road mesh is used as Spline (It’s float through) .

I goggled it and it’s seems that it could be a kind of bug, do you have some infos about it ? Thanks a lot !

i had the same problem with a rail on the side of the road (with the landscape spline tool)
and i figured out you have to split the collision mesh a few times so that it could bend correctly.
hope that helps

You mean split the mesh in 3ds max i suppose . The idea was passed through my mind but was not sure. I ll try this this evening and tell you if its work. Thanks for your answer :slight_smile:

I’m afraid that I don’t understand well what you mean by “bend collision mesh” . I add more vertex in my mesh (by chamfer them)

The result is the same when I do the auto convexe collision in UE4, no change .

Hi Komega,

The collision issue isn’t related to your spline but rather it starts with your mesh. You will need to make the collision mesh in your 3D modeling software for the most accurate response. Using the Auto-convex tool will work well for small round or solid objects but not where you have to be in a recessed part of the mesh or want clean wall collision.

[Here is a link with some test files I made. There is the FBX with the collision setup already and a Max file with the mesh and collision model inside for you to see how it works. I save it as 2010 because I’m not sure what version you are on.][1]

To explain what needs to be made in Max take a look at this attached image and I’ll explain what’s going on.

The top mesh is my single mesh race track that has been UV unwrapped.

The bottom is 3 meshes that make up my collision. They are all named UCX_“name of base mesh” (ie. UCX_RaceTrack)

There are three meshes with this for each face that needs to be collision. One for each side wall and a box for the floor.

When I export these to FBX I export everything all together. When you import the “UCX_” prefix will be recognized as collision and applied to the mesh with the corresponding name.

[Be sure to take a look at our documentation on collision on this page for a better understanding.][2]

If you have any questions feel free to ask!


Thanks Tim it’s what I done just before you edit your post and it works nicely this way. It’s just a bit sad that a powerfull engine like UE4 could not calculate without UCX mesh. Anyway now it s ok for me :slight_smile: Another Post Resolved by this great community !

hey, i see your problem is solved - i meant exactly that - you have to split the collision mesh (UCX) because the spline tool wil bend the mesh and therefore also your collision mesh. it can only do that at the edges though is what i thought. so my conclusion was to add more edges (to the ucx) and it worked for me.

good luck

As you pointed out the Use Complex as Simple will work but this is not an efficient way to handle collision. The best way has always been to make your own collision mesh to get the best results.

We did announce in our Engine News 6/18 update on the forums that we do have something in the works for generating collision better in UE4. You can read about that here and see some of the images.

It is still recommended that for the best solution for collision and giving you, the user, the most control would be to create your own collision meshes in your modeling software.