如何在给定的持续时间内创建 0..1..0..1..0 等的脉动值？

发布于 2024-09-05 08:33:52 字数 263 浏览 5 评论 0原文

我正在编写一些代码，其中有一个带有成员 time 的 Time 对象。 Time.time 给出我的应用程序启动以来的时间（以秒为单位）（浮点值）。现在我想创建一个介于 0 和 1 之间的脉动值，然后再次从 1 到 0，这将继续进行，直到应用程序停止。

我正在考虑使用 sin() 但不知道将什么作为参数传递给它来创建这个脉冲值。

我将如何创造这种脉动的价值？

亲切的问候，波勒克斯

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半步萧音过轻尘 2024-09-12 08:33:52

你提到使用 sin()，所以我猜你希望它在 0 和 1 之间连续脉冲。

这样就可以了：

float pulse(float time) {
    const float pi = 3.14;
    const float frequency = 10; // Frequency in Hz
    return 0.5*(1+sin(2 * pi * frequency * time));
}

1/频率 = 0.1 秒 是周期，即 1 之间的时间。

You mention using sin(), so I guess you want it to pulse continuously between 0 and 1.

Something like this will do:

float pulse(float time) {
    const float pi = 3.14;
    const float frequency = 10; // Frequency in Hz
    return 0.5*(1+sin(2 * pi * frequency * time));
}

1/frequency = 0.1 second is the period, which is the time between 1's.

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征棹 2024-09-12 08:33:52

x = 1 - x 怎么样？
或者，如果您希望它基于时间，请使用 Timer % 2

哦，您也想要 0 到 1 之间的值。
Math.Abs(100 - (计时器 % 200)) / 100 怎么样
其中计时器类似于 DateTime.Now.TimeOfDay.TotalMilliseconds

编辑：
我的测试表明，这比 Sin 方法快两倍多。对于 100 万次迭代，sin 方法需要 0.048 秒，而 Abs 方法大约需要 0.023 秒。当然，您还可以从两者中得到不同的波形。 Sin 产生正弦波，而 Abs 产生三角波。

static void Main(string[] args)
{
   System.Diagnostics.Stopwatch sw = new System.Diagnostics.Stopwatch();
   sw.Start();
   const int count = 1000000;
   float[] results = new float[count];
   for (int i = 0; i < count; i++)
   {
      results[i] = AbsPulse(i/1000000F);
      //results[i] = SinPulse(i / 1000000F);
   }
   sw.Stop();
   Console.WriteLine("Time Elapsed: {0} seconds", sw.Elapsed.TotalSeconds);
   char[,] graph = new char[80, 20];
   for (int y = 0; y <= graph.GetUpperBound(1); y++)
      for (int x = 0; x <= graph.GetUpperBound(0); x++)
         graph[x, y] = ' ';
   for (int x = 0; x < count; x++)
   {
      int col = x * 80 / count;
      graph[col, (int)(results[x] * graph.GetUpperBound(1))] = 'o';
   }
   for (int y = 0; y <= graph.GetUpperBound(1); y++)
   {
      for (int x = 0; x < graph.GetUpperBound(0); x++)
         Console.Write(graph[x, y]);
      Console.WriteLine();
   }
}

static float AbsPulse(float time)
{
   const int frequency = 10; // Frequency in Hz
   const int resolution = 1000; // How many steps are there between 0 and 1
   return Math.Abs(resolution - ((int)(time * frequency * 2 * resolution) % (resolution * 2))) / (float)resolution;
}

static float SinPulse(float time)
{
   const float pi = 3.14F;
   const float frequency = 10; // Frequency in Hz
   return 0.5F * (1 + (float)Math.Sin(2 * pi * frequency * time));
}

How about x = 1 - x?
Or if you want it to be time based use Timer % 2

Oh, you wanted the values between 0 and 1 as well.
how about Math.Abs(100 - (Timer % 200)) / 100
Where timer is something like DateTime.Now.TimeOfDay.TotalMilliseconds

Edit:
My tests indicate that this is more than twice as fast as the Sin method. For 1 million iterations, the sin method takes .048 seconds while the Abs method takes about .023 seconds. Also, you get different waveforms out of the two, of course. Sin produces a Sine wave, while Abs produces a triangular wave.

static void Main(string[] args)
{
   System.Diagnostics.Stopwatch sw = new System.Diagnostics.Stopwatch();
   sw.Start();
   const int count = 1000000;
   float[] results = new float[count];
   for (int i = 0; i < count; i++)
   {
      results[i] = AbsPulse(i/1000000F);
      //results[i] = SinPulse(i / 1000000F);
   }
   sw.Stop();
   Console.WriteLine("Time Elapsed: {0} seconds", sw.Elapsed.TotalSeconds);
   char[,] graph = new char[80, 20];
   for (int y = 0; y <= graph.GetUpperBound(1); y++)
      for (int x = 0; x <= graph.GetUpperBound(0); x++)
         graph[x, y] = ' ';
   for (int x = 0; x < count; x++)
   {
      int col = x * 80 / count;
      graph[col, (int)(results[x] * graph.GetUpperBound(1))] = 'o';
   }
   for (int y = 0; y <= graph.GetUpperBound(1); y++)
   {
      for (int x = 0; x < graph.GetUpperBound(0); x++)
         Console.Write(graph[x, y]);
      Console.WriteLine();
   }
}

static float AbsPulse(float time)
{
   const int frequency = 10; // Frequency in Hz
   const int resolution = 1000; // How many steps are there between 0 and 1
   return Math.Abs(resolution - ((int)(time * frequency * 2 * resolution) % (resolution * 2))) / (float)resolution;
}

static float SinPulse(float time)
{
   const float pi = 3.14F;
   const float frequency = 10; // Frequency in Hz
   return 0.5F * (1 + (float)Math.Sin(2 * pi * frequency * time));
}

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眼泪淡了忧伤 2024-09-12 08:33:52

我认为正弦函数是理想的，但您需要调整周期和比例。

正弦函数产生 -1 和 1 之间的结果，但您想要在 0 和 1 之间。要正确缩放它，您需要 (sin(x)+1)/2。

正弦函数从零开始，在 pi/2 处变为 1，在 pi 处再次为零，在 3*pi/2 处变为 -1，并在 2*pi 处返回到零。按比例缩放，第一个零将出现在 3*pi/2 处，之后的第一个最大值将出现在 5/2*pi 处。因此，上一个公式中的 x 为 (2*time + 3) * pi/2。

把它们放在一起：(sin((2*time.time + 3) * pi/2) + 1) / 2

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小傻瓜 2024-09-12 08:33:52

您希望它多久脉冲一次？

假设您想在 10 秒内从 0 变为 1。

float pulseValueForTime(int sec) {
    int pulsePoint = sec % 10;
    float pulsePercent = (float)pulsePoint / (float)10;
    float pulseInTermsOfPI = (pulsePercent * 2 * PI) - PI;
    float sinVal = MagicalSinFunction(pulseInTermsOfPI); // what framework you use to compute sin is up to you... I'm sure you can google that!
    return (sinVal + 1) / 2; // sin is between 1 and -1, translate to between 0 and 1
}

How often do you want it to pulse?

Let's say you want to go from 0 to 1 over 10 seconds.

float pulseValueForTime(int sec) {
    int pulsePoint = sec % 10;
    float pulsePercent = (float)pulsePoint / (float)10;
    float pulseInTermsOfPI = (pulsePercent * 2 * PI) - PI;
    float sinVal = MagicalSinFunction(pulseInTermsOfPI); // what framework you use to compute sin is up to you... I'm sure you can google that!
    return (sinVal + 1) / 2; // sin is between 1 and -1, translate to between 0 and 1
}

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