运行时更换天空盒材质的贴图

效果：用户可以自定义给天空盒更换自己喜欢的贴图
条件：场景天空盒的材质shader选择Skybox/Panoramic.

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using System.Linq;
using VRM;
using System.Diagnostics;
using System.Threading;
using Debug = UnityEngine.Debug;
using UnityEngine;
using System.Collections;
using System;
using System.Runtime.InteropServices;

[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 class LocalDialog
{
    //链接指定系统函数       打开文件对话框
    [DllImport("Comdlg32.dll", SetLastError = true, ThrowOnUnmappableChar = true, CharSet = CharSet.Auto)]
    public static extern bool GetOpenFileName([In, Out] OpenFileName ofn);
    public static bool GetOFN([In, Out] OpenFileName ofn)
    {
        return GetOpenFileName(ofn);
    }

    //链接指定系统函数        另存为对话框
    [DllImport("Comdlg32.dll", SetLastError = true, ThrowOnUnmappableChar = true, CharSet = CharSet.Auto)]
    public static extern bool GetSaveFileName([In, Out] OpenFileName ofn);
    public static bool GetSFN([In, Out] OpenFileName ofn)
    {
        return GetSaveFileName(ofn);
    }
}


public class TestData : MonoBehaviour
{
    bool isLoadTexture = false;
    Texture2D texture;

    private void OnGUI()
    {
        if(GUI.Button(new Rect(0,0,400,60),"加载图片"))
        {
            OpenFileName openFileName = new OpenFileName();
            openFileName.structSize = Marshal.SizeOf(openFileName);
            //openFileName.filter = "";
            openFileName.file = new string(new char[256]);//文件原始路径，格式（D:\3-图片-花.jpg）
            openFileName.maxFile = openFileName.file.Length;
            openFileName.fileTitle = new string(new char[64]);//文件名字(带格式后缀)，格式（3-图片-花.jpg）
            openFileName.maxFileTitle = openFileName.fileTitle.Length;
            openFileName.initialDir = Application.streamingAssetsPath.Replace('/', '\\');//默认路径
            openFileName.title = "窗口标题";
            openFileName.flags = 0x00080000 | 0x00001000 | 0x00000800 | 0x00000008;

            if (LocalDialog.GetSaveFileName(openFileName))
            {
                Debug.Log(openFileName.file);
                Debug.Log(openFileName.fileTitle);

                StartCoroutine(DownloadAndSave(openFileName.file, ( progress,texture2d) => 
                {
                    texture = new Texture2D(4000, 2000);
                    texture.LoadImage(texture2d);
                    isLoadTexture = true;
                    RenderSettings.skybox.mainTexture = (Texture)texture;
                    DynamicGI.UpdateEnvironment();
                }));
            }
        }

        //if(isLoadTexture)
        //{
        //    GUI.DrawTexture(new Rect(0, 0, texture.width, texture.height), texture);
        //}
    }


    public static IEnumerator DownloadAndSave(string url, Action< string, byte[]> Finish = null)//路径，名字
    {
        WWW www = new WWW(url);
        if (www.error != null)
        {
            Debug.Log("error:" + www.error);
        }
        if (www.isDone)
        {
            Debug.Log("完成了");
            byte[] bytes = www.bytes;
            Debug.Log(bytes.Length);
            if (Finish != null)
            {
                Finish( Loading, bytes);
            }
        }
    }
}