UV mapping icosphere

Unity Engine
1

I’m creating an Icosphere with a script, it generates the sphere perfectly but i’m having trouble UV mapping it.
Using this code for the mapping

Vector2[] uvs = new Vector2[mesh.vertices.Length];

for (int i = 0; i < mesh.vertices.Length; i++) {
       
uvs [i] = new Vector2 ((Mathf.Atan2 (mesh.vertices [i].z, mesh.vertices [i].x) / Mathf.PI / 2), (Mathf.Acos (mesh.vertices [i].y / radius) / Mathf.PI));

}

I get an Icosphere that looks like this

2613724--183341--test.jpg
2613724--183341--test.jpg1437×697 73.8 KB

I’m not sure how to go about this.

2

That line happens because theres no UV seam, the last batch of triangles loops back from a high uv value to zero, duplicate the verts along the seam so you can have 2 uv coords in the same spot

3

@hpjohn I am facing that exact same problem and to avoid duplicating the question I will first try asking you here directly (also bumping this question in the process). Your conceptual explanation is good, however I am finding it difficult to implement a proper solution to that.

My current code is slightly different from the OP:

     Vector3[] nVertices = mesh.vertices;
        Vector2[] UVs = new Vector2[nVertices.Length];

        for (var i = 0; i < nVertices.Length; i++)
        {
            var unitVector = nVertices[i].normalized;
            Vector2 ISOuv = new Vector2(0, 0);
            ISOuv.x = (Mathf.Atan2(unitVector.x, unitVector.z) + Mathf.PI) / Mathf.PI *0.5f;
            ISOuv.y = (Mathf.Acos(unitVector.y) + Mathf.PI) / Mathf.PI - 1;
            UVs[i] = new Vector2(ISOuv.x, ISOuv.y);
        }
        mesh.uv = UVs;
4

@andSol , did you find any solution for that?

5

A cheat/simple solution which works for boulders , asteroids and similar objects is to make sure that the U (or V - whichever you have the problem with) coordinate starts at 0.0 , goes to 1.0 and then back to 0.0.

The opposite side of the rock will have the same texture but … no seam.
Still you will have polar problems and such.
Super cheaty version is to simply

… Mathf.Atan( x , Mathf.Abs(z) ) …