int uvIndex;
        float u = 0.0f; // empty tile
        float v = Globals.UV_v;
        for (i=0; i<tiles.Length;i++)
        {
            uvIndex = i * 4;
            uvs[uvIndex + 0] = new Vector2(u, v);
            uvs[uvIndex + 1] = new Vector2(u+Globals.UV_u, v);
            uvs[uvIndex + 2] = new Vector2(u, v+Globals.UV_u);
            uvs[uvIndex + 3] = new Vector2(u+Globals.UV_u, v+Globals.UV_u);
        }