Landscape Spline Mesh incorrect Custom Collision

Development World Creation
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1

Hi, When using a custom collision with a landscape spline mesh the following issue occurs. I am confident that I am using the correct setup, both in the exported mesh fromMaya and the settings in UE4.

Here are the steps to reproduce the issue:

  1. Create the spline mesh (for me in Maya).
  2. Add a custom collision (in Maya).
  3. Here is the end result when adding railing and collision to the road. Notice the correct naming.

229577-capture3.png
229577-capture3.png1425×394 12.9 KB

  1. Export the mesh and the collision and import it into UE4. In the import settings I turned off Auto Generate Collision.
  2. In the mesh viewer I can see that the collision has been exported, but it is not working properly. In step 3 you can see that the collision has a lot of subdivisions, they seem to have dissappeared in UE4. I did some testing and noticed that if I give every other line an offset, it works better, so something seems to go wrong if all lines are alligned on the same axis.

229579-capture4.png
229579-capture4.png1074×407 228 KB

  1. The issue that occurs is that the subdivisions in the collision is not imported correctly. When this mesh is being used with a spline, the mesh itself deforms correctly but the collision is not.

229582-capture5.png
229582-capture5.png1004×575 427 KB

  1. As you can see, it appears as if the subdivisions are gone form the collision mesh, making the collision appear as very blocky and not as smooth as the spline mesh.
  2. However, on the left side of the mesh (the outer side of the corner) there seem to be some subdivisions.

229584-capture6.png
229584-capture6.png1065×562 495 KB

  1. I am really not sure what to think about this, but driving on it is not smooth at all so something is wrong here.

All help is appreciated! Cheers

2

Further investigation has shown that this (for the moment) needs to be done in a separate way. If I understand it correctly collision meshes is not allowed to be concave, they can only be convex. So when the spline deforms the mesh, one side becomes concave and the other convex, I.E. that is why in the pictures above one side seems to be normal but not the other one.

Solution: Each subdivision of the custom collision is a seperate object. In maya it is named UCX_Road_01, UCX_Road_02 and so on. This solved it and the vehicles are now driving smoothly on the landscape spline meshes!

However I find it strange that it needs to be done this way. If it can’t handle concave objects then this should be stated much clearer in the documentation, so that people in the future wont have to spend as much time as I have on trying to debug this.

Thanks!

3

This worked! Thnx!