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Tessellation problem with two materials assigned to one mesh

I have a character designed in Maya. The base mesh has a material assigned to it, then I selected the head polygons and assigned a new material to them. Afterward I exported it out as a FBX.

When I assigned the distance-based tessellation material to the body it tessellates fine, and keeps a clean division at the neck where the other material should start for the head. If I assign the same tessellated material to the head, some of the neck vertexes moves down the negative Z axis. Any thoughts on why that could be happening? Could that have something to do with my weighting? I only ask because if I export the same model as an obj, assign identical materials, the problem doesn’t happen.

I also imported my obj into a new Maya scene, exported that to an fbx, imported it into U4, the materials work correctly.

Thoughts anyone?

Thanks.

I had the same issue since 4.0.x. I think this post https://forums.unrealengine.com/showthread.php?6969-Rigged-mesh-has-vertex-tearing probably was the same problem. I’ve seen other reports of tessellation spikes not just with rigged skeletal meshes. Only answer I’ve seen so far has been more-or-less “disable tessellation”.

I’ve so far gotten around it by doing one-material-per-mesh where I need tessellation and combining the meshes in a Blueprint character (and “Set Master Pose Component” to keep animation synched.) Not having to do that would be nice, though. This is just a hobby for me and there’s so much other aspects to learn as a beginner that I hadn’t pursued the issue further

Does anyone else know of a solution for this?

Maybe it’s an issue with the normals around the neck. Is the head actually attached to the body or is it split apart?

Its one mesh with two materials assigned; one for the head and one for the body.

Here’s an AnswerHub item dating back to June which I think is the same problem:

https://answers.unrealengine.com/questions/54091/dx11-tessellation-broken-in-42-completely-and-tota.html

It didn’t help me, but it may help you.