#include <iostream>
#include <ratio>
#include <chrono>
 
constexpr auto steady_min = std::chrono::steady_clock::time_point::min();
 
int main()
{
    auto last_frame = steady_min;
    std::chrono::duration<float, std::milli> game_time {0.0F};
 
    for (std::size_t count = 0; count < 5; ++count) {
        auto current_frame = std::chrono::steady_clock::now();
        // 若是首帧则初始化计时器：
        if (last_frame == steady_min)
            last_frame = current_frame;
        game_time += current_frame - last_frame;
        std::cout << "Drawing frame at " << game_time.count() << " ms\n";
        // 在时间偏移 game_time 绘制帧……
    }
}