Unity selects and loads files on PC

`   
using System.IO;   

[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Auto)]
public class OpenFileName
{
    public int structSize = 0;
    public IntPtr dlgOwner = IntPtr.Zero;
    public IntPtr instance = IntPtr.Zero;
    public String filter = null;
    public String customFilter = null;
    public int maxCustFilter = 0;
    public int filterIndex = 0;
    public String file = null;
    public int maxFile = 0;
    public String fileTitle = null;
    public int maxFileTitle = 0;
    public String initialDir = null;
    public String title = null;
    public int flags = 0;
    public short fileOffset = 0;
    public short fileExtension = 0;
    public String defExt = null;
    public IntPtr custData = IntPtr.Zero;
    public IntPtr hook = IntPtr.Zero;
    public String templateName = null;
    public IntPtr reservedPtr = IntPtr.Zero;
    public int reservedInt = 0;
    public int flagsEx = 0;
}

public static OpenFileName A_OpenFileName()
{
    OpenFileName ofn = new OpenFileName();

    ofn.structSize = Marshal.SizeOf(ofn);

    ofn.filter = ".txt Files(*.txt)\0 *.txt";

    ofn.file = new string(new char[256]);

    ofn.maxFile = ofn.file.Length;

    ofn.fileTitle = new string(new char[64]);

    ofn.maxFileTitle = ofn.fileTitle.Length;

    ofn.initialDir = Directory.GetCurrentDirectory(); //默认路径  (当前工程路径)
    ofn.title = "选择航线数据";

    ofn.defExt = "txt";
    ofn.flags = 0x00080000 | 0x00001000 | 0x00000800 | 0x00000200 | 0x00000008;
    return ofn;
}

//调用系统打开文件窗口
public class DllTest
{
    [DllImport("Comdlg32.dll", SetLastError = true, ThrowOnUnmappableChar = true, CharSet = CharSet.Auto)]
    public static extern bool GetOpenFileName([In, Out] OpenFileName ofn);

    public static bool GetOpenFileName1([In, Out] OpenFileName ofn)
    {
        return GetOpenFileName(ofn);
    }
}
`  

Instructions

    `    
 private void TextCsv()
  {
    var ofn = A_OpenFileName();
    if (DllTest.GetOpenFileName(ofn))
    {
        if (!File.Exists(ofn.file))
        {
            return;
        }
        lineArray = File.ReadAllLines(ofn.file);      //读取选取的文件的所有行
        int a = lineArray.Length;

        for (int j = 0; j < lineArray.Length; j++)
        {
            string[] strPos = lineArray[j].Split(',');
            if (null == strPos)
            {

            }
            float x = float.Parse(strPos[0]);
            float y = float.Parse(strPos[1]);
            float z = float.Parse(strPos[2]);

            Vector3 tempPos = new Vector3(x, y, z);

            GameObject tempObi = Instantiate(LoadPathPoint);
            tempObi.transform.position = tempPos;
            tempObi.transform.parent = tempLoadPE.gameObject.transform;
}`