duck

    MeshFilter meshFilter = AddComponent<MeshFilter>();
    Mesh mesh = new Mesh();

    Vector3[] verts = new Vector3[] {
        new Vector3(0, 0, 0),
        new Vector3(1, 0, 0),
        new Vector3(1, 0, 1),
        new Vector3(0, 0, 1)
    };

    int[] tris = new int[] { 0, 2, 1, 3, 2, 0 };

    Vector2[] uv1s = new Vector2[] {
        new Vector2(0, 0),
        new Vector2(1, 0),
        new Vector2(1, 1),
        new Vector2(0, 1)
    };


    // Assign mesh properties
    mesh.vertices = verts;
    mesh.uv = uv1s;
    mesh.triangles = tris;
    mesh.RecalculateNormals();
    mesh.RecalculateBounds();
    meshFilter.mesh = planeMesh;