UV mirroring issue

Unity Engine
1

I am generating meshes and have to create the UVs. Going smooth until this happened.

Any ideas?

@Kurt-Dekker

 MeshFilter gbMF = gradeBeam.GetComponent<MeshFilter>();
                    Vector3[] vertices = gbMF.mesh.vertices;
                    Vector2[] uvs = new Vector2[vertices.Length];

                    //bot
                    uvs[2] = new Vector2(1, 0);
                    uvs[3] = new Vector2(1, 9);
                    uvs[0] = new Vector2(0, 9);
                    uvs[1] = new Vector2(0, 0);
                    //top
                    uvs[6] = new Vector2(1, 0);
                    uvs[7] = new Vector2(1, 9);
                    uvs[4] = new Vector2(0, 9);
                    uvs[5] = new Vector2(0, 0);
                    //  -z
                    uvs[10] = new Vector2(0, 9);
                    uvs[11] = new Vector2(1, 9);
                    uvs[8] = new Vector2(1, 0);
                    uvs[9] = new Vector2(0, 0);
                    //-x
                    uvs[14] = new Vector2(1, 0);
                    uvs[15] = new Vector2(1, 1);
                    uvs[12] = new Vector2(0, 1);
                    uvs[13] = new Vector2(0, 0);
                    //z
                    uvs[18] = new Vector2(9, 0);
                    uvs[19] = new Vector2(9, 1);
                    uvs[16] = new Vector2(0, 1);
                    uvs[17] = new Vector2(0, 0);
                    //x
                    uvs[22] = new Vector2(1, 0);
                    uvs[23] = new Vector2(1, 1);
                    uvs[20] = new Vector2(0, 1);
                    uvs[21] = new Vector2(0, 0);

                    gbMF.mesh.uv = uvs;
                    gbMF.mesh.RecalculateBounds();
                    gbMF.mesh.RecalculateNormals();

The top, bottom and both ends are good to go its the other two faces that are jacked up with this mirroring.

This is my first time coding the UVs so these may look out of order…I am doing it visually.

100000001196987--1060733--UVmirroring.jpg
100000001196987--1060733--UVmirroring.jpg1818Ă—753 319 KB

8159879--1060802--UVmirroring2.png
8159879--1060802--UVmirroring2.png1657Ă—838 71 KB

2

Is these 9 entries just typos?? I think you cannot reliably go more than a few units past 0-1 in UVs… I know I used some iOS hardware a few years back that would stop wrapping if U or V went beyond about -4 or +4

3

Since it is a low res concrete texture( about a foot IRL ) I made I started at 1,1…but it didn’t look good so I walked it out until it looked even. For this example the mesh is 40’ long and 2’ tall, 2’ wide. I exported out of my app a FBX and in Maya it is exactly how it is in code…except these two(4 tris) are not showing up correctly. The two bottom corner UVs are at the location of the top corner UVs.

4

Grab an abcd texture, slap it on a material, and one by one force all UVs to a tiny corner of the texture, or perhaps just the “A”. Then one by one put them back properly. Or even remove all triangles and add them back one at a time until you can hone in on where the bad data is coming from.

8159999--1060811--abcd.png 8159999--1060814--abcd.png

1 Like
5

I just did that…and this is what those two sides need to be to get rid of it.

// -z                  
uvs[8] = new Vector2(9, 0);
uvs[9] = new Vector2(9, 1);
uvs[10] = new Vector2(1, 0);
uvs[11] = new Vector2(1, 1);

That does not seem right though. But I don’t have enough exp with UVs to know any better…but it looks good.

1 Like
6

Just exported it to check in Maya and it is good to go…But it is not clean…/

8160062--1060829--UVmirroring3.png
8160062--1060829--UVmirroring3.png786Ă—889 34.1 KB

7

Well, you haven’t shown how your vertices are generated. The UV coordinates live in normal / tangent space of the triangle that is rendered. So the order of your UV coordinates depends on the actual relative position of your vertices. Maybe you have some weird flip in the vertices?

What’s already suspicious is that your UVs are sometimes clockwise sometimes counterclockwise. That would tell me your vertices / triangles are all over the place. So I’m pretty sure the issue is elsewhere, Most likely the positioning of the vertices or how you constructed the triangles for that face.

8

I am using a geometry library a co-worker created so I am not really sure how that is happening…But yeah, you’re correct…something is going on with the way the vertices are being constructed. Those two sides are flipped.

All I do is give it basically a length, width and length to extrude it. Then have to give it UVs as he didn’t do that.

Just confirmed…the triangles were done in another library.

9

I’m not sure if this would help, but I made a triplanar UV mapper for exactly this purpose: rapid prototyping in Blender where you forget to do UV unwraps and just want some kind of texture evenly spread over your object.

https://github.com/kurtdekker/makegeo/blob/master/makegeo/Assets/setuvtoworld/SetUVToWorld.cs

10

@Kurt-Dekker I did use that, but when I export out, the UVs were way to far out, I imagine because of not having them to begin with. I tried using the material UV tiling to bring them closer to 1,1 but that didn’t work on export.