How to import UCX from Maya

Development Asset Creation
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1

Hi!

I have used Maya to create the Tetris blocks:

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To create also the collisions, I have selected that block, pressed Ctrl. + D, and set it as child of the block with the same name, adding it UCX_ prefix:

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To export to Unreal I use Send to Unreal menu with both objects selected:
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In Unreal editor, when I import it I deselect Generate Missing Collision option:

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When I open the Mesh in the Mesh editor and select Show simple collision I get this:

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Why isn’t importing collisions correctly?

Thanks.

2

I think unreal sees the shape as concave instead of convex and ignores the UCX_ collision in that case.

3

Thanks.

How can I add a collision that fits the mesh?

4

Go into the static mesh Collision =>Auto Convex Collision => find Convex Decomposition (should be below details panel) adjust collision slider complexity as needed => Apply!

Or you can add the collisions by hand (by adding box collisions) in case of simple stuff like tetris blocks.

5

Adding another solution here as this thread is high in Google results for this issue:

  • I use the Game Exporter function in Maya as it’s convenient for batch exporting many objects at once
  • I use FBX 2020 as the Exporter for Unreal 5.4.4
  • Important - in the cog icon next to the FBX Version make sure “Include Children” is ticked
  • Name correctly - eg for MeshName make an object in Maya called UCX_MeshName for a convex object
  • Middle mouse drag the UCX object onto the Mesh in the Maya Outliner to make it a child of your Mesh
  • Select the Mesh (it should select the UCX as well) and Export to fbx using the Game Exporter window
  • Ensure “Generate Missing Collision” is turned off in the Unreal window
  • I prefer to keep “One Convex Hull Per UCX” ticked but you can experiment with this

Your collision should now import correctly, check with Show > Simple Collision