这是我尝试制作 2D 粒子模拟的代码片段
static long lastTime = 0;
static double GetDeltaTime()
{
long now = DateTime.Now.Millisecond;
double dT = (now - lastTime); // / 1000
lastTime = now;
Console.WriteLine(dT);
return dT;
}
很明显,它将返回自上次调用该方法以来的时间(以毫秒为单位)。唯一的问题,这就是它打印的内容
393
1
0
0
0
0
0
0
0
0
0
...
好吧,也许那只是因为每次通过的时间不到一毫秒。所以我把它改成
static long lastTime = 0;
static double GetDeltaTime()
{
long now = DateTime.Now.Ticks; // Changed this to ticks
double dT = (now - lastTime); // / 1000
lastTime = now;
Console.WriteLine(dT);
return dT;
}
但这仍然打印
6.35476136625848E+17
20023
0
0
0
0
0
0
...
如果“粒子模拟器”不能很好地表明我的程序有多复杂,那么我只想说,完成一次传递需要比 0 滴答更长的时间!
那么这里发生了什么?
------- 代码引用------
整个类(class)仅供引用
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using System.Windows.Forms;
using System.Threading;
namespace _2D_Particle_Sim
{
static class Program
{
public static Particle2DSim pSim;
static Form1 form;
public static Thread update = new Thread(new ThreadStart(Update));
/// <summary>
/// The main entry point for the application.
/// </summary>
[STAThread]
static void Main()
{
Application.EnableVisualStyles();
Application.SetCompatibleTextRenderingDefault(false);
form = new Form1();
pSim = new Particle2DSim(form);
pSim.AddParticle(new Vector2(-80, -7), 5);
pSim.AddParticle(new Vector2(8, 7), 3);
Console.WriteLine("Opening Thread");
Program.update.Start();
Application.Run(form);
// System.Threading.Timer timer;
// timer = new System.Threading.Timer(new TimerCallback(Update), null, 0, 30);
}
static void Update()
{
GetDeltaTime();
while (true)
{
pSim.Update(GetDeltaTime());
}
}
static long lastTime = 0;
static double GetDeltaTime()
{
long now = DateTime.Now.Ticks;
double dT = (now - lastTime); // / 1000
lastTime = now;
Console.WriteLine(dT);
return dT;
}
}
}
另外,如果我对代码复杂程度的类比还不够,这里是 Particle2DSim 类的更新方法
public void Update(double deltaTime)
{
foreach (Particle2D particle in particles)
{
List<Particle2D> collidedWith = new List<Particle2D>();
Vector2 acceleration = new Vector2();
double influenceSum = 0;
// Calculate acceleration due to Gravity
#region Gravity
foreach (Particle2D particle2 in particles)
{
double dist2 = particle.position.Distance2(particle.position);
double influence = dist2 != 0 ? particle2.mass / dist2 : 0;
acceleration.Add(particle.position.LookAt(particle2.position) * influence);
influenceSum += influence;
if (dist2 < ((particle.radius + particle2.radius) * (particle.radius + particle2.radius)) && dist2 != 0)
{
collidedWith.Add(particle2);
}
}
acceleration.Divide(influenceSum);
#endregion
particle.Update(deltaTime);
// Handle Collisions
#region Collisions
if (collidedWith.Count > 0)
{
Console.WriteLine("Crash!");
double newMass = 0;
double newRadius = 0;
Vector2 newPosition = new Vector2();
Vector2 newVelocity = new Vector2();
newMass += particle.mass;
newRadius += Math.Sqrt(particle.radius);
newPosition += particle.position;
newVelocity += particle.velocity * particle.mass;
particles.Remove(particle);
foreach (Particle2D particle2 in collidedWith)
{
newMass += particle2.mass;
newRadius += Math.Sqrt(particle2.radius);
newPosition += particle2.position;
newVelocity += particle2.velocity * particle2.mass;
particles.Remove(particle2);
}
newPosition.Divide(collidedWith.Count + 1);
newVelocity.Divide(newMass);
AddParticle(newPosition, newVelocity, newMass, newRadius);
}
#endregion
}
}
最佳答案
问题是您正在使用 DateTime
来尝试测量时间的流逝。 DateTime
用于表示日期和时间,但不用于测量耗时。
使用 stopwatch
类测量时间:
Stopwatch sw = new Stopwatch();
sw.Start();
// Do something here
sw.Stop();
Console.WriteLine(sw.ElapsedMilliseconds);
// or sw.ElapsedTicks
有关差异的更多详细信息,请查看 Eric Lippert 的博客 HERE
关于C# Delta 时间实现,我们在Stack Overflow上找到一个类似的问题:https://stackoverflow.com/questions/26110228/