Static Mesh Nanite assemblies RT proxy/ Nanite fallback vertex count issues

Development Rendering
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1

Hi! I have ran into an issue trying out the new Nanite Assembly builder utilities. When building an assembly normally and not changing any settings (i.e. using the Relative Error method), the resulting assembly will have 100% of it’s triangles in the fallback and in the ray tracing proxy. Switching the fallback generation method to triangle percentage properly simplifies the mesh. Is there anything else I need to do when generating assemblies this way?

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2

Steps to Reproduce

  1. Enable Nanite Assembly Editor Utilities plugin;
  2. Kitbash a couple Nanite static meshes in a scene;
  3. Select all the kitbashed meshes, right click them and go to Scripted Asset Actions -> Nanite Assemblies -> Create New Static Mesh Assembly from selection. Save the assembly;
  4. Open the resulting static mesh asset. Make sure that you are using an Auto fallback target (or Relative error);
  5. Check the vertex and triangle count for the Nanite mesh and it’s fallback. They will be the same;
  6. Change the Fallback Target to Percent Triangles, set the Fallback Triangle Percent to 15 and apply changes;
  7. Now the fallback will have less triangles compared to the normal nanite mesh (as expected).
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3

Hi Fedor,

Thanks for your report! I’ve reproduced the issue and should have a fix submitted for the UE 5.8 release.

Thanks again!

-Jamie

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4

Hi Fedor,

The fix was submitted to UE5/Main in CL 51139777 yesterday. It’s a two-line fix so should be very easy to integrate.

-Jamie

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5

Thank you! If the fix is already in, do you have a changelist available by any chance so that we can merge this while we’re on 5.7? :blush:

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