debug的时候需要等很长时间读模型，查资料发现了两种快速读取大文件的方法。
test 1:每次读一个字符串
test 2、3一次读取整个文件
{//test 1
string buf;
clock_t start = clock();
ifstream fin(objpath);
while (fin >> buf);
fin.close();
clock_t end = clock();
cout << "time : " << ((double)end - start) / CLOCKS_PER_SEC << "s\n";
}
{//test 2
clock_t start = clock();
ifstream fin(objpath, std::ios::binary);
vector<char> buf(fin.seekg(, std::ios::end).tellg());
fin.seekg(, std::ios::beg).read(&buf[], static_cast<std::streamsize>(buf.size()));
fin.close();
clock_t end = clock();
cout << "time : " << ((double)end - start) / CLOCKS_PER_SEC << "s\n";
}
{//test 3
clock_t start = clock();
ifstream fin(objpath);
stringstream buf;
buf << fin.rdbuf();
fin.close();
clock_t end = clock();
cout << "time : " << ((double)end - start) / CLOCKS_PER_SEC << "s\n";
}
文件大小为112M，花费的时间分别为：
time : .809s
time : .092s
time : .213s
于是将loader改成了第二种。