Vertex color does not work on Skeletal Mesh with Nanite enabled

Development Rendering
, ,
1

Hello,

I have a skeletal mesh asset, it has some data stored in vertex color. And I can see the vertex color is correct in the skeletal mesh editor.

I assign a material which uses VertexColor node (also Abs node and Frac node) and plug it into BaseColor output.

If the skeletal mesh asset has Nanite enabled - the material shows all black.

If the skeletal mesh asset has Nanite disabled - the material shows correct vertex colors.

Does Nanite + Skeletal Mesh supports vertex color?

[Image Removed]

[Image Removed]

2

Steps to Reproduce

  1. Open any project with Version: 5.6.1-44394996+++UE5+Release-5.6 or 5.7 preview
  2. Import the attached assets
  3. Drag the skeletal mesh (it’s a cube) to a level and assign the material
  4. Right click the skeletal mesh asset to make sure it has nanite enabled

Actual: The cube is black.

Expected: The cube shows colorful vertex colors.

Reproducible:

5.6.1-44394996+++UE5+Release-5.6

5.7 preview

3

Hi,

thanks for reporting this issue and providing repro steps. I have investigated the issue and could not find it in the list of known issues, so I’ve filed a bug report. When the issue gets added to the public issue tracker, I will post the link here so you can track its progress.

Many thanks,

Sam

4

Hi again,

this is the link to the issue on the public issue tracker: https://issues.unrealengine.com/issue/UE-347708

If you have further questions, please let me know.

Thanks again,

Sam

5

Yes i can confirm the skeletal turn full white with nanite enabled

also manipulating a Skeletal mesh in Eu 5.7 (not 5.6) turn the model partialy whyte

to goes around keep a 5.6 session and re export to 5.7 when finished

6

Can confirm this is still an issue in 5.8.2 (5.8.2-56702186+++UE5+Release-5.8), and can confirm that it is not solved with the update.

To diagnose this, I did the following:

  1. Created a simple material (M_Test): Vertex Color RGBA > Base Color
  2. Created a geometry torus in Unreal. Sculpted and painted on vertex colors. Exported it to FBX from Unreal.
  3. Imported it back into Unreal, and it works fine as a Static Mesh.
  4. Loaded it into Blender, confirmed and validated its Attributes / Vertex Colors data etc
  5. Exported from Blender > Unreal and it works as a Static Mesh.
  6. Added basic armature to working Blender file, exported with armature.
  7. Imported and dropped torus in as Skeletal Mesh, applied M_Test material, and vertex colors work.
  8. Toggled on Nanite, and the material turns white. Toggling back off, the colors are immediately restored.

Thanks,

Ethan