unity 调用win32打开文件管理器 选中图片 获取立方体的材质信息 将图片赋给立方体的材质纹理

在Unity中调用Win32 API打开文件管理器，可以使用以下代码：

using System.Runtime.InteropServices;

public class FileDialog
{
    [DllImport("User32.dll", SetLastError = true, CharSet = CharSet.Auto)]
    private static extern bool SetForegroundWindow(IntPtr hWnd);

    [DllImport("user32.dll", SetLastError = true)]
    static extern IntPtr FindWindow(string lpClassName, string lpWindowName);

    [DllImport("user32.dll", SetLastError = true)]
    static extern IntPtr SetParent(IntPtr hWndChild, IntPtr hWndNewParent);

    [DllImport("Comdlg32.dll", SetLastError = true, CharSet = CharSet.Auto)]
    static extern bool GetOpenFileName([In, Out] FileDialogArgs args);

    public static string OpenFile()
    {
        FileDialogArgs args = new FileDialogArgs();
        args.structSize = Marshal.SizeOf(args);
        args.filter = "Image Files (*.jpg, *.jpeg, *.png)|*.jpg;*.jpeg;*.png|All files (*.*)|*.*";
        args.file = new string(new char[256]);
        args.maxFile = args.file.Length;
        args.fileTitle = new string(new char[64]);
        args.maxFileTitle = args.fileTitle.Length;
        args.initialDir = UnityEngine.Application.dataPath;  // 打开对话框时显示的初始目录
        args.title = "Select Image";  // 对话框标题

        IntPtr parentWnd = FindWindow(null, "Unity");  // Unity的窗口标题为"Unity"
        SetForegroundWindow(parentWnd);  // 将Unity窗口置于前台
        args.hwndOwner = parentWnd;
        SetParent(parentWnd, IntPtr.Zero);  // 将Unity窗口的父窗口设置为桌面窗口，避免对话框在Unity窗口后面

        if (GetOpenFileName(args))
        {
            return args.file;
        }

        return null;
    }

    [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Auto)]
    private class FileDialogArgs
    {
        public int structSize;
        public IntPtr hwndOwner;
        public IntPtr hInstance;
        public string filter;
        public string customFilter;
        public int maxCustomFilter;
        public int filterIndex;
        public string file;
        public int maxFile;
        public string fileTitle;
        public int maxFileTitle;
        public string initialDir;
        public string title;
        public int flags;
        public short fileOffset;
        public short fileExtension;
        public IntPtr defExt;
        public IntPtr custData;
        public IntPtr hook;
        public string templateName;
        public IntPtr reservedPtr;
        public int reservedInt;
        public int flagsEx;
    }
}

然后在需要打开文件管理器的地方调用 `FileDialog.OpenFile()` 方法即可。

接下来获取立方体的材质信息，可以使用以下代码：

Renderer renderer = gameObject.GetComponent<Renderer>();
Material material = renderer.sharedMaterial;

最后将图片赋给立方体的材质纹理，可以使用以下代码：

string imagePath = FileDialog.OpenFile();
if (imagePath != null)
{
    Texture2D texture = new Texture2D(2, 2);
    byte[] imageData = File.ReadAllBytes(imagePath);
    texture.LoadImage(imageData);
    material.mainTexture = texture;
}

其中 `FileDialog.OpenFile()` 方法用于打开文件管理器选中图片，然后将图片加载到 `Texture2D` 对象中，并将其赋给材质的 `mainTexture` 属性。