// ObjファイルとMtlファイルを書き出す
 private void ExportObjFile(string objName, Mesh mesh, Material[] mats, string folderPath, string fileName, Transform meshTrans)
 {
     ObjExporter.MeshToFile(objName, mesh, mats, meshTrans, folderPath + "/" + fileName);
     ObjExporter.MaterialsToMtl(mats, folderPath + "/" + objName + ".mtl");
 }