Strange mesh texture created by code in Unity

Question

I'm learning how to mesh by code in Unity, but the texture is weird as in the image, does anyone know why this is? I created the UV Map as it is in the code, searched Google and Unity documentation a lot, and saw that I should use the array vertices to map the UV, but I think I did something wrong

My Code:

public Vector3[] verts = {
    new Vector3(-0.5f, 0.5f, 0f), new Vector3(0.5f, 0.5f, 0f),
    new Vector3(0.5f, -0.5f, 0f), new Vector3(-0.5f, -0.5f, 0f),
    new Vector3(-0.2f, 0.3f, 0f), new Vector3(0.2f, 0.3f, 0f),
    new Vector3(0.2f, -0.1f, 0f), new Vector3(-0.2f, -0.1f, 0f),
    new Vector3(-0.2f, 0.3f, 0f), new Vector3(0.2f, 0.3f, 0f),
    new Vector3(0.2f, -0.1f, 0f), new Vector3(-0.2f, -0.1f, 0f),
    new Vector3(-0.2f, 0.3f, 0.1f), new Vector3(0.2f, 0.3f, 0.1f),
    new Vector3(0.2f, -0.1f, 0.1f), new Vector3(-0.2f, -0.1f, 0.1f),
    new Vector3(-0.2f, 0.3f, 0.1f), new Vector3(0.2f, 0.3f, 0.1f),
    new Vector3(0.2f, -0.1f, 0.1f), new Vector3(-0.2f, -0.1f, 0.1f),
    new Vector3(-0.5f, 0.5f, 0.1f), new Vector3(-0.5f, -0.5f, 0.1f),
    new Vector3(-0.5f, -0.5f, 0.1f), new Vector3(-0.5f, -0.5f, 0.1f),
    new Vector3(-0.5f, -0.5f, 0.1f), new Vector3(-0.5f, -0.5f, 0.1f),
    new Vector3(-0.5f, -0.5f, 0.1f), new Vector3(-0.5f, -0.5f, 0.1f),
    new Vector3(-0.5f, -0.5f, 0.1f), new Vector3(-0.5f, -0.5f, 0.1f),
    new Vector3(-0.5f, -0.5f, 0.1f), new Vector3(-0.5f, -0.5f, 0.1f),
    new Vector3(-0.5f, -0.5f, 0.1f), new Vector3(-0.5f, -0.5f, 0.1f),
    new Vector3(-0.5f, -0.5f, 0.1f), new Vector3(-0.5f, -0.5f, 0.1f),
    new Vector3(-0.5f, -0.5f, 0.1f), new Vector3(-0.5f, -0.5f, 0.1f),
    new Vector3(-0.5f, -0.5f, 0.1f), new Vector3(-0.5f, -0.5f, 0.1f),
    new Vector3(-0.5f, -0.5f, 0.1f), new Vector3(-0.5f, -0.5f, 0.1f),
    new Vector3(-0.5f, -0.5f, 0.1f), new Vector3(-0.5f, -0.5f, 0.1f),
    new Vector3(-0.5f, -0.5f, 0.1f), new Vector3(-0.5f, -0.5f, 0.1f),
    new Vector3(0.5f, 0.5f, 0.1f), new Vector3(0.5f, -0.5f, 0.1f)
 };
 public int[] tris = {
     0,1,4,1,5,4,1,2,5,2,6,5,2,3,6,3,7,6,3,0,7,0,4,7,8,9,12,9,13,12,9,10,13,10,14,13,10,11,14,11,15,14,11,8,15,8,12,15,20,0,3,20,3,21,0,20,46,0,46,1,1,46,47,1,47,2,3,2,42,2,47,45,46,20,17,20,16,17,20,19,16,20,32,15,31,14,15,31,47,14,47,46,14,46,17,14
 };

MeshFilter mF = gameObject.GetComponent<MeshFilter> ();
Mesh msh = new Mesh ();
msh.vertices = verts;
msh.triangles = tris;
Vector2[] uvs = new Vector2[verts.Length];
for (int i = 0; i < uvs.Length; i++){ //uv map
    uvs[i] = new Vector2(verts[i].x, verts[i].y);
 }
 msh.uv = uvs;
 msh.RecalculateNormals ();
 mF.mesh = msh;

Answer 1

Since you already discovered that shared vertices were causing this issue you may want to test this code if it even works. May become useful at some point. It aims at assigning UVs at mesh computation time (special shaders no longer needed), but requires that adjacent triangles with angle between their independent normals > PI/4 share no vertices anywhere (in other words: no shared vertices between different sides of a cube)

using UnityEngine;
public class NewBehaviourScript : MonoBehaviour
{
    [SerializeField] MeshFilter meshFilter = null;
    Vector3[] vertices = { vertices goes here };
    int[] triangles = { indices goes here };
    void Start ()
    {
        Mesh mesh = new Mesh();
        meshFilter.mesh = mesh;

        Vector2[] uvs = new Vector2[ vertices.Length ];
        int numTriangles = triangles.Length / 3;
        for( int t=0 ; t<numTriangles ; t++ )
        {
            int ia = triangles[ t*3 ];
            int ib = triangles[ t*3+1 ];
            int ic = triangles[ t*3+2 ];

            Vector3 va = vertices[ ia ];
            Vector3 vb = vertices[ ib ];
            Vector3 vc = vertices[ ic ];

            Vector3 normal = Vector3.Cross( vb-va , vc-va ).normalized;
            float dotForward = Vector3.Dot( normal , Vector3.forward );
            float dotRight = Vector3.Dot( normal , Vector3.right );
            float dotUp = Vector3.Dot( normal , Vector3.up );

            if( dotForward>0.7071f )
            {
                // front projection
                uvs[ ia ] = new Vector2{ x=-va.x , y=va.y };
                uvs[ ib ] = new Vector2{ x=-vb.x , y=vb.y };
                uvs[ ic ] = new Vector2{ x=-vc.x , y=vc.y };
            }
            else if( dotForward<-0.7071f  )
            {
                // back projection
                uvs[ ia ] = new Vector2{ x=va.x , y=va.y };
                uvs[ ib ] = new Vector2{ x=vb.x , y=vb.y };
                uvs[ ic ] = new Vector2{ x=vc.x , y=vc.y };
            }
            else if( dotRight>0.7071f )
            {
                // right projection
                uvs[ ia ] = new Vector2{ x=-va.z , y=va.y };
                uvs[ ib ] = new Vector2{ x=-vb.z , y=vb.y };
                uvs[ ic ] = new Vector2{ x=-vc.z , y=vc.y };
            }
            else if( dotRight<-0.7071f )
            {
                // left projection
                uvs[ ia ] = new Vector2{ x=va.z , y=va.y };
                uvs[ ib ] = new Vector2{ x=vb.z , y=vb.y };
                uvs[ ic ] = new Vector2{ x=vc.z , y=vc.y };
            }
            else if( dotUp>0.7071f )
            {
                // top projection
                uvs[ ia ] = new Vector2{ x=-va.x , y=va.z };
                uvs[ ib ] = new Vector2{ x=-vb.x , y=vb.z };
                uvs[ ic ] = new Vector2{ x=-vc.x , y=vc.z };
            }
            else
            {
                // bottom projection
                uvs[ ia ] = new Vector2{ x=va.x , y=va.z };
                uvs[ ib ] = new Vector2{ x=vb.x , y=vb.z };
                uvs[ ic ] = new Vector2{ x=vc.x , y=vc.z };
            }
        }

        mesh.vertices = vertices;
        mesh.triangles = triangles;
        mesh.uv = uvs;

        mesh.RecalculateNormals();
    }
}

Answer 2

I suspect that perspective texture correction is disabled in your case because

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