Flutter通过flutter_unity_widget嵌入Unity3D

实现方案：采用flutter开源组件flutter_unity_widget

环境搭建Unity

1、创建flutter项目flutter_unity_demo

2、在pubspec.paml文件dependencies添加flutter_unity_widget: ^2022.2.0，执行Pub get导入组件

3、在工程目录下创建unity文件夹

4、在unity目录下创建unity_demo的3D工程

5、下载flutter_unity_widget提供的unity插件

在unity_demo项目Assets右键导入（import package）插件unitypackages（注：我导入的是FlutterUnityIntegration-v4-WithDemo）会得到以下目录，这个时候Flutter打包的方式如下图

7、修改Assets/FlutterUnityIntegration/Editor/Build.cs文件

DoBuildAndroid方法：
var options = BuildOptions.AcceptExternalModificationsToPlayer;

替换为：

var options = BuildOptions.AllowDebugging;

EditorUserBuildSettings.exportAsGoogleAndroidProject = true;

BuildIOS 方法：

var options = BuildOptions.AcceptExternalModificationsToPlayer;

替换为：

var options = BuildOptions.AllowDebugging;

8、为了方便测试创建Cube，绑定Assets/FlutterUnityIntegration/Demo/Rotote.cs脚本并调整好摄像头对准新创建的Cube

Flutter加载unity

1. 创建UnityPage页面实现以下代码

import 'package:flutter/material.dart';
import 'package:flutter_unity_widget/flutter_unity_widget.dart';

class UnityPage extends StatefulWidget {
  const UnityPage({super.key});

  @override
  _UnityPageState createState() => _UnityPageState();
}

class _UnityPageState extends State<UnityPage> {
  UnityWidgetController? _unityWidgetController;
  double _sliderValue = 0.0;

  @override
  void initState() {
    // TODO: implement initState
    super.initState();
  }

  @override
  void dispose() {
    // TODO: implement dispose
    _unityWidgetController?.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    // TODO: implement build
    return Scaffold(
      appBar: AppBar(
        title: const Text("this Unity"),
      ),
      body: Container(
        child: Stack(
          children: [
            UnityWidget(
                onUnityCreated: onUnityCreated,
                onUnityMessage: onUnityMessage,