### 创建测试结构体

```cs
[StructLayout(LayoutKind.Sequential)]
public struct Point
{
    public float X { get; set; }
    public float Y { get; set; }
    public float Z { get; set; }
}
```

### 测试函数

这里使用Marshal.PtrToStructure、Span两种方式

```cs
    public class Test
    {
        private readonly  IntPtr data;
        private const int count = 2000000;
        public Test()
        {
            var points = new Point[count];
            for (int i = 0; i < points.Length; i++)
            {
                points[i].X = i;
            }
            data = Marshal.AllocHGlobal(points.Length * Marshal.SizeOf(typeof(Point)));

            var ptr = data;
            for (int i = 0; i < points.Length; i++)
            {
                Marshal.StructureToPtr(points[i], ptr, false);
                ptr += Marshal.SizeOf(typeof(Point));
            }
        }
        [Benchmark]
        public  Point[] Method1()
        {
            var points = new Point[count];
            var ptr = data;

            for (int i = 0; i < count; i++)
            {
                points[i] = Marshal.PtrToStructure<Point>(ptr);
                ptr += Marshal.SizeOf(typeof(Point));
            }
            return points;
        }
        [Benchmark]
        public unsafe Point[] Method2()
        {
            var points = new Span<Point>(data.ToPointer(), count);
            return points.ToArray();
        }

    }
```



### 结果对比

| Method  | Mean      | Error     | StdDev    |
| ------- | ---------:| ---------:| ---------:|
| Method1 | 94.891 ms | 1.8537 ms | 3.4360 ms |
| Method2 | 6.625 ms  | 0.0676 ms | 0.0599 ms |

C/C++结构体数组指针与C#数组转换

### 环境

   - WPF

   - .net8.0-windows
  
  ### 引用第三方库
  
  ```shell
    HelixToolkit.SharpDX.Core.Wpf
  ```
  
  ### MainWindow.xaml中引入控件
  
  ```xaml
  <hx:Viewport3DX
    x:Name="view1"
    Title="Dynamic Points and Lines"
    BackgroundColor="Black"
    CameraMode="Inspect"
    ClipToBounds="False"
    CoordinateSystemLabelForeground="Green"
    EffectsManager="{Binding EffectsManager}"
    EnableRenderFrustum="False"
    FixedRotationPoint="0,0,0"
    FixedRotationPointEnabled="True"
    IsPanEnabled="True"
    IsZoomEnabled="True"
    ShowCameraInfo="True"
    ShowCameraTarget="True"
    ShowCoordinateSystem="True"
    ShowFrameDetails="True"
    ShowFrameRate="True"
    ShowTriangleCountInfo="True"
    ShowViewCube="True"
    SubTitle="change number of points and check FPS"
    TextBrush="Black"
    UseDefaultGestures="True"
    ZoomExtentsWhenLoaded="True">
    <hx:Viewport3DX.Camera>
        <hx:OrthographicCamera UpDirection="0,-1,0" />
    </hx:Viewport3DX.Camera>
    <hx:Viewport3DX.InputBindings>
        <KeyBinding Key="B" Command="hx:ViewportCommands.BackView" />
        <KeyBinding Key="F" Command="hx:ViewportCommands.FrontView" />
        <KeyBinding Key="U" Command="hx:ViewportCommands.TopView" />
        <KeyBinding Key="D" Command="hx:ViewportCommands.BottomView" />
        <KeyBinding Key="L" Command="hx:ViewportCommands.LeftView" />
        <KeyBinding Key="R" Command="hx:ViewportCommands.RightView" />
        <KeyBinding Command="hx:ViewportCommands.ZoomExtents" Gesture="Control+E" />
        <MouseBinding Command="hx:ViewportCommands.Rotate" Gesture="RightClick" />
        <MouseBinding Command="hx:ViewportCommands.Zoom" Gesture="MiddleClick" />
        <MouseBinding Command="hx:ViewportCommands.Pan" Gesture="LeftClick" />
    </hx:Viewport3DX.InputBindings>
  
    <hx:PointGeometryModel3D
        x:Name="model"
        FixedSize="True"
        Geometry="{Binding Points}"
        IsRendering="True"
        Color="White" />
  </hx:Viewport3DX>
  ```
  
  ### 创建MainViewModel
  
  如果需要每个点自定义颜色，需要初始化Colors集合，且PointGeometryModel3D的颜色需要为White
  
  ```cs
   public PointGeometry3D Points { get; }
   public MainViewModel()
   {
       Points = new PointGeometry3D
       {
          IsDynamic = true,
         Positions = new Vector3Collection(),
         Colors = new Color4Collection(),
       };
  }
  ```
  
  ### 更新数据点
  
  ```cs
  viewModel.Points.Positions.Clear();
  viewModel.Points.Colors.Clear();
  foreach (var point in points)
  {
    viewModel.Points.Positions.Add(p);
    viewModel.Points.Colors.Add(new Color4(1,0,1, 1.0f));
  }
  ```
  
  ### 刷新数据
  
  ```cs
  viewModel.Points.UpdateVertices();
  ```
  ### 效果展示
  
![Snipaste_2024-08-11_21-38-22.png](/static/img/85030fdf57768aed7d35399d41c829f8.Snipaste_2024-08-11_21-38-22.webp)

WPF渲染激光点云数据

- 新建文本文档
- 输入以下文本
  
  ```vb
  CreateObject ("InternetExplorer.Application").Visible=true
  ```
- 重命名后缀为.vbs
- 双击运行

Win10、Win11打开IE浏览器

### RTMP推流

```
ffmpeg -re -stream_loop -1 -i xxxx.mp4 -acodec copy -vcodec copy -f flv rtmp://127.0.0.1/live/test
```
### 合并多张图片
```
ffmpeg -i %02d.jpg -filter_complex tile=1x4 output.jpg
```
### 获取AVFrame信息
```
ffprobe -show_frames -select_streams v -of xml xxxx.mp4 >videoframes.info
```
### 获取AVPacket信息
```
ffprobe -show_packets -select_streams v -of xml xxxx.mp4 >videoframes.info
```

FFMPEG常用命令

### 一、获取证书(里使用win-acme获取)
- 下载win-acme(https://github.com/win-acme/win-acme/releases)

- 选择M:Create certificate (full options)
![image.png](/static/img/00ff1e82facd051f4ef7c7b1e78c6d50.image.webp)

- 选择 2: Manual input，并输入域名   
![image.png](/static/img/0b4ee258300b7d80cdc2f2584462b2ad.image.webp)

- 选择 4: Single certificate
![image.png](/static/img/83bc7c213bd9833950af0b71e721aadb.image.webp)

- 选择认证方式，这里使用DNS认证: 6: [dns] Create verification records manually (auto-renew not possible)
![](https://chenxuejian.cn/static/img/80800245b8e6fa04359f023781fa02a7.image.webp)

- 选择2: RSA key
![image.png](/static/img/ef00dd5273852557f8ac6db3058d344f.image.webp)

- 选择3: PFX archive
![image.png](/static/img/ce4e16f9bc485055536020a09d46acde.image.webp)

- 输入保存地址

- 自己选择是否有密码
![image.png](/static/img/97c1f2f69c00a5f6963d079898038a3b.image.webp)

- 选择无其它操作，并开始域名认证
![image.png](/static/img/b6d70a963a4ead774e7a77661db1ba67.image.webp)

- 按照提示在域名管理中心，创建一个TXT解析记录

- 删除该记录
### 二、导入证书
- 将证书上传到Jellyfin

- 在控制台->高级->联网中选择自定义SSL证书路径,如果有密码需要填写密码

- 重启Jellyfin