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一、创建一个新的flutter项目

并在该项目文件下新建一个unity文件夹

二、在unity目录下新建一个unity项目

1.新建项目

三、导入unitypackage

1.去github https://github.com/juicycleff/flutter-unity-view-widget 将unityPackages下载下来

2.在unity中导入unitypackage.


这里看自己情况导入v4或者v4.1.0(我也不知道有什么区别，当练手试试水)

导入成功后Assets会多出一个FlutterUnityIntegration文件夹，unity菜单栏会有一个flutter选项


3.给3D模型绑定脚本（这里用的是demo里面的现成脚本），将rotate.cs拖到模型上

四、unity配置

在unity菜单栏 file>building settings,切换Platform为Android，打开Player Settings

五、导出unityLibrary

在导出过程中报错

根据错误提示，打开build.cs
在DoBuildAndroid方法中

//将var options = BuildOptions.AcceptExternalModificationsToPlayer替换

var options = BuildOptions.AllowDebugging;
EditorUserBuildSettings.exportAsGoogleAndroidProject = true;

在DoBuildIOS方法中

//将var options = BuildOptions.AcceptExternalModificationsToPlayer替换
 var options = BuildOptions.AllowDebugging;

然后保存一下，重新导出就可以了

六、导入unityLibrary

导出成功后会在flutter的Android文件下生成一个unityLibrary

然后用AS打开Android文件，在build的过程中会报错提示

在gradle.properties文件里加上

unityStreamingAssets=.unity3d, google-services-desktop.json, google-services.json, GoogleService-Info.plist 

然后重新build，build成功。再接着运行一下程序看是否有问题
在运行的时候又报错了！！！！

根据错误提示，minSdkVersion 16 改成19，接着运行！然后结合报错！！

提示NDK is not install
这个时候打开local.properties，设置ndk，需要注意的是其中的版本要换成你自己unity的版本，我的是2020.3.30f1c1

ndk.dir=/Applications/Unity/Hub/Editor/2020.3.30f1c1/PlaybackEngines/AndroidPlayer/NDK

再接着运行！终于运行成功！！

七、引入flutter_unity_widget插件

引入插件，pub get，https://pub.flutter-io.cn/packages/flutter_unity_widget查看最新的插件版本

flutter_unity_widget: ^2020.3.25

接着运行一下flutter项目
然后报错！！！！

按照提示，将ext.kotlin_version = ‘1.6.0’
再接着build，运行，然后又又又报错！！！T^T

根据提示包冲突了，那我就在所有引用unity-classes包的地方，将implementation改成compileOnly
再运行一下，终于好了！！T^T

八、flutter_unity_widget运用

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

class UnityTestPage extends StatefulWidget {
  const UnityTestPage({Key? key}) : super(key: key);

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

class _UnityTestPageState extends State<UnityTestPage> {
  UnityWidgetController? _unityWidgetController;
  double _sliderValue = 0.0;

  @override
  void initState() {
    super.initState();
  }

  @override
  void dispose() {
    _unityWidgetController!.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(title: Text('Test Unity')),
        body: Container(
          width: double.infinity,
          child: Stack(
            children: [
            ///这里需要多看看源码里面的参数
              UnityWidget(
                onUnityCreated: onUnityCreated,
                onUnityMessage: onUnityMessage,
                onUnitySceneLoaded: onUnitySceneLoaded,
                fullscreen: false,
              ),
              Positioned(
                  bottom: 10,
                  left: 20,
                  child: Container(
                    width: 500,
                    child: Column(
                      children: [
                        Slider(
                          onChanged: (value) {
                            setState(() {
                              _sliderValue = value;
                            });
                            setRotationSpeed(value.toString());
                          },
                          value: _sliderValue,
                          min: 0,
                          max: 20,
                        ),
                        Row(
                          mainAxisAlignment: MainAxisAlignment.spaceBetween,
                          children: [
                            MaterialButton(
                              onPressed: () {
                                _unityWidgetController!.pause();
                              },
                              child: Text("Pause"),
                            ),
                            MaterialButton(
                              onPressed: () {
                                _unityWidgetController!.resume();
                              },
                              child: Text("Resume"),
                            ),
                          ],
                        ),
                      ],
                    ),
                  )),
            ],
          ),
        ),
      ),
    );
  }

  void setRotationSpeed(String speed) {
  //这里需要看看给3d模型绑定的脚本
    _unityWidgetController!.postMessage(
      'Cube',
      'SetRotationSpeed',
      speed,
    );
  }

  void onUnityMessage(message) {
    print('Received message from unity: ${message.toString()}');
  }

  void onUnitySceneLoaded(scene) {
    print('Received scene loaded from unity: ${scene.name}');
    print('Received scene loaded from unity buildIndex: ${scene.buildIndex}');
  }

  // Callback that connects the created controller to the unity controller
  void onUnityCreated(controller) {
    this._unityWidgetController = controller;
  }
}

九、效果

运行程序，看看效果