除了我的代码之外，还有什么原因让chrono Time加速的吗

Question

在我的游戏开始几秒钟后，一切都加快了。我找不到我的代码有任何问题，但肯定有问题。我想知道我的显卡是否正在全速前进。如有任何建议，我们将不胜感激，谢谢！

#include <SFML/Graphics.hpp>
#include <iostream>
#include <chrono>
#include <ctime>    
#include "PongGame.h"
int main()
{
PongGame game(10);
sf::RenderWindow window(sf::VideoMode(1500, 900), "SFML works!");
float UPDATE_INTERVAL = 900000000.0f;
float lag = 0.0f;
typedef std::chrono::high_resolution_clock Time;
typedef std::chrono::milliseconds ms;
typedef std::chrono::duration<float> fsec;
auto prevTime = Time::now();
while (window.isOpen())
{
auto currTime = Time::now();
fsec fs = currTime - prevTime;
ms d = std::chrono::duration_cast<ms>(fs);
lag += d.count();
//std::cout << "lag1: " << lag << "n";
while (lag > UPDATE_INTERVAL) {
std::cout << "loop";
sf::Event currEvent;
while (window.pollEvent(currEvent))
{
if (currEvent.type == sf::Event::Closed) { window.close(); }
}
game.PollKeys();
game.Update(1.0f);
game.Render(1.0f, &window);
//lag -= UPDATE_INTERVAL;
lag = 0;
std::cout << "lag2: " << lag << "n";
}
}
return 0;
}

@Howard Hinnant

我现在用时间毫秒来比较所有的东西。我已经对代码进行了大量的研究，我只是不明白为什么它会像现在这样加速。这是新代码：

#include <SFML/Graphics.hpp>
#include <iostream>
#include <chrono>
#include <ctime>    
#include "PongGame.h"
int main()
{
typedef std::chrono::high_resolution_clock hiResTime;
typedef std::chrono::milliseconds ms;
typedef std::chrono::high_resolution_clock::time_point time_point;
PongGame game(10);
sf::RenderWindow window(sf::VideoMode(1500, 900), "SFML works!");
time_point prevTime = hiResTime::now();
time_point currTime = hiResTime::now();
const ms UPDATE_INTERVAL(99999999);
ms lag(0);
while (window.isOpen())
{
prevTime = currTime;
time_point currTime = hiResTime::now();
ms currInterval = std::chrono::duration_cast<std::chrono::milliseconds>(currTime - prevTime);
lag += currInterval;
if (lag > UPDATE_INTERVAL) {
//std::cout << "loop";
sf::Event currEvent;
if ((window.pollEvent(currEvent)) && (currEvent.type == sf::Event::Closed)) { window.close(); }
game.PollKeys();
game.Update(1.0f);
game.Render(1.0f, &window);
//lag -= UPDATE_INTERVAL;
lag = ms(0);
}
}
return 0;
}

Answer 1

在旧版本的代码中，您忘记了更新prevTime。在当前版本中，您仍然没有这样做，因为prevTime = currTime;中的currTime是直接在main()中定义的，但它从未更新，因为time_point currTime = hiResTime::now();定义了具有相同名称的新变量(这是允许的，因为它在嵌套块中(，而不是更新以前定义的变量。因此第一个currTime总是包含游戏开始时间。