OBJ import changes vertex order with Optimize Mesh set to "Nothing"

[wfenz]

When updating my Unity project from 2019.4 to 2020.1, I found that the vertices in imported OBJ meshes have a different order now, although “Optimize Mesh” in the Import Settings is set to “Nothing”. Reimporting the mesh does not help.

[jackjortega]

Hey, I noticed this same issue, wondering if this is intentional?

My project expects vertex ordering to be unchanged, but using the same settings that I used in 2019.4 yields an altered vertex order in 2020.1.

My project assigns vertex colors to create an animation, so having the vertex order change pretty much breaks it completely.

The number of vertices in the mesh is identical in both versions, but the order is evidently changed based on my vertex colors being assigned to the wrong vertices.

[wfenz]

Yes, I also use the vertex indices for an animation… If this is intentional, then I wonder why you can still choose “Optimize Vertex Order” in the mesh import settings - before, unchecking this kept the order of the vertices unchanged, now it does not seem to do anything…

[epicardio_1]

having the same problem. Any answers?

[epicardio_1]

@wfenz

When updating my Unity project from 2019.4 to 2020.1, I found that the vertices in imported OBJ meshes have a different order now, although “Optimize Mesh” in the Import Settings is set to “Nothing”. Reimporting the mesh does not help.

Hi, have you found a solution to this? I have the same problem.

[wfenz]

Sorry, no. I’m still using version 2019 at the moment…

[JackOrtega-Pro]

The problem seems to persist in 2021.2.12f1.

[binpan]

same problem here, any unity official answers

[hanquel85]

I have same problem.
Is there any solution?

[deram_scholzara]

BuuuuuuUUUUmp.

Seriously, what’s up with this?

I’m seeing the index order shift issue in 2021.3.16f1, but not in 2019.4 (as the original poster said).

[deram_scholzara]

Relevant discussion topic:

Retaining vertex indexes when importing meshes

Hi guys. I’m trying to do a simple mesh morphing program. The code is easy, but the problem occurs 'cause Unity seems to change the index order of my vertices. So, when I do the morph, I get a bad-formed mesh. I have the same number of vertices, 'cause I changed the Import Options → OptimeMesh to Off, so, morph is not really the problem. The problem is the vertices order of the imported objects. But is there something that I could do to keep the vertices order of the meshes? Original: [12814-c…