UGUI_游戏菜单场景切换

事件委托

GameManger（空物体）+GameManger脚本——重要的方式

public class GameManger : MonoBehaviour {

    public void OnStartGame(string sceneName)
    {
        Application.LoadLevel(sceneName);
    }

}

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.SceneManagement;

public class GameManger : MonoBehaviour
 {
    public void OnStartGame(int sceneIndex)
    {
        //Application.LoadLevel(sceneIndex);
         SceneManager.LoadScene();
    }
}

Unity3D  SceneManager场景管理用法总结

一、Unity关卡

Unity 使用过程中关卡加载和卸载是大多数三维引擎都要提供的基本功能。 
因为关卡切换在游戏中非常常用。 
在之前的版本中Unity的关卡切换使用的是：

Application.loadedLevel()；

• 1看看Application类，此时这个类的功能比较繁杂，比较多。只看与关卡相关的：

  [Obsolete("Use SceneManager.LoadScene")]
         public static void LoadLevel(string name);

         [Obsolete("Use SceneManager.LoadScene")]
         public static void LoadLevel(int index);

         [Obsolete("Use SceneManager.LoadScene")]
         public static void LoadLevelAdditive(string name);

         [Obsolete("Use SceneManager.LoadScene")]
         public static void LoadLevelAdditive(int index);
   //
         // 摘要:
         //     ///
         //     Unloads all GameObject associated with the given scene. Note that assets are
         //     currently not unloaded, in order to free up asset memory call Resources.UnloadAllUnusedAssets.
         //     ///
         //
         // 参数:
         //   index:
         //     Index of the scene in the PlayerSettings to unload.
         //
         //   scenePath:
         //     Name of the scene to Unload.
         //
         // 返回结果:
         //     ///
         //     Return true if the scene is unloaded.
         //     ///
         [Obsolete("Use SceneManager.UnloadScene")]
         public static bool UnloadLevel(string scenePath);
         //
         // 摘要:
         //     ///
         //     Unloads all GameObject associated with the given scene. Note that assets are
         //     currently not unloaded, in order to free up asset memory call Resources.UnloadAllUnusedAssets.
         //     ///
         //
         // 参数:
         //   index:
         //     Index of the scene in the PlayerSettings to unload.
         //
         //   scenePath:
         //     Name of the scene to Unload.
         //
         // 返回结果:
         //     ///
         //     Return true if the scene is unloaded.
         //     ///
         [Obsolete("Use SceneManager.UnloadScene")]
         public static bool UnloadLevel(int index);

注解： 
这是之前的Application中的关卡的加载和卸载。 
当然现在在新版本（Unity5.3以上）中，有了新的变化，那就是SceneManager类了处理。

二、Untiy的SceneManager类

自从Unity5.3版本，Unity 的关卡切换就添加了新的SceneManager的类来处理。 
当然要安装过了Unity文档帮助，并且给下面路径一样，就可以知道在本地打开。 
本地链接： 
file:///C:/Program%20Files/Unity5.3.0/Editor/Data/Documentation/en/Manual/UpgradeGuide53.html 
也可以在Unity中搜索SceneManager来查看。

 #region 程序集 UnityEngine, Version=0.0.0.0, Culture=neutral, PublicKeyToken=null
 // H:\Unity\UnityProject\ShiftLevels\Library\UnityAssemblies\UnityEngine.dll
 #endregion

 using UnityEngine.Internal;

 namespace UnityEngine.SceneManagement
 {
     //
     // 摘要:
     //     ///
     //     Scene management at run-time.
     //     ///
     public class SceneManager
     {
         public SceneManager();

         public static int sceneCount { get; }
         //

         public static int sceneCountInBuildSettings { get; }

         public static Scene GetActiveScene();

         public static Scene[] GetAllScenes();
         // 参数:
         //   index:
         //     Index of the scene to get. Index must be greater than or equal to 0 and less
         //     than SceneManager.sceneCount.
         public static Scene GetSceneAt(int index);

         // 返回结果:
         //     ///
         //     The scene if found or an invalid scene if not.
         //     ///
         public static Scene GetSceneByName(string name);

         //     Searches all scenes added to the SceneManager for a scene that has the given
         //     asset path.
         //     ///
         //
         // 参数:
         //   scenePath:
         //     Path of the scene. Should be relative to the project folder. Like: "AssetsMyScenesMyScene.unity".
         public static Scene GetSceneByPath(string scenePath);
         [ExcludeFromDocs]
         public static void LoadScene(int sceneBuildIndex);
         [ExcludeFromDocs]
         public static void LoadScene(string sceneName);

         // 参数:
         //   sceneName:
         //     Name of the scene to load.
         //
         //   sceneBuildIndex:
         //     Index of the scene in the Build Settings to load.
         //
         //   mode:
         //     Allows you to specify whether or not to load the scene additively. See SceneManagement.LoadSceneMode
         //     for more information about the options.
         public static void LoadScene(int sceneBuildIndex, [DefaultValue("LoadSceneMode.Single")] LoadSceneMode mode);

         // 参数:
         //   sceneName:
         //     Name of the scene to load.
         //
         //   sceneBuildIndex:
         //     Index of the scene in the Build Settings to load.
         //
         //   mode:
         //     Allows you to specify whether or not to load the scene additively. See SceneManagement.LoadSceneMode
         //     for more information about the options.
         public static void LoadScene(string sceneName, [DefaultValue("LoadSceneMode.Single")] LoadSceneMode mode);
         [ExcludeFromDocs]
         public static AsyncOperation LoadSceneAsync(int sceneBuildIndex);
         [ExcludeFromDocs]
         public static AsyncOperation LoadSceneAsync(string sceneName);

         // 参数:
         //   sceneName:
         //     Name of the scene to load.
         //
         //   sceneBuildIndex:
         //     Index of the scene in the Build Settings to load.
         //
         //   mode:
         //     If LoadSceneMode.Single then all current scenes will be unloaded before loading.
         public static AsyncOperation LoadSceneAsync(int sceneBuildIndex, [DefaultValue("LoadSceneMode.Single")] LoadSceneMode mode);

         // 参数:
         //   sceneName:
         //     Name of the scene to load.
         //
         //   sceneBuildIndex:
         //     Index of the scene in the Build Settings to load.
         //
         //   mode:
         //     If LoadSceneMode.Single then all current scenes will be unloaded before loading.
         public static AsyncOperation LoadSceneAsync(string sceneName, [DefaultValue("LoadSceneMode.Single")] LoadSceneMode mode);
         //

         // 参数:
         //   sourceScene:
         //     The scene that will be merged into the destination scene.
         //
         //   destinationScene:
         //     Existing scene to merge the source scene into.
         public static void MergeScenes(Scene sourceScene, Scene destinationScene);
         //
         // 摘要:
         //     ///
         //     Move a GameObject from its current scene to a new scene. /// It is required that
         //     the GameObject is at the root of its current scene.
         //     ///
         //
         // 参数:
         //   go:
         //     GameObject to move.
         //
         //   scene:
         //     Scene to move into.
         public static void MoveGameObjectToScene(GameObject go, Scene scene);
         //

         // 返回结果:
         //     ///
         //     Returns false if the scene is not loaded yet.
         //     ///
         public static bool SetActiveScene(Scene scene);

         //     ///
         public static bool UnloadScene(string sceneName);
         //
         // 摘要:
         //     ///
         //     Unloads all GameObjects associated with the given scene. Note that assets are
         //     currently not unloaded, in order to free up asset memory call Resources.UnloadAllUnusedAssets.
         //     ///
         //
         // 参数:
         //   sceneBuildIndex:
         //     Index of the scene in the Build Settings to unload.
         //
         //   sceneName:
         //     Name of the scene to unload.
         //
         // 返回结果:
         //     ///
         //     Returns true if the scene is unloaded.
         //     ///
         public static bool UnloadScene(int sceneBuildIndex);
     }
 }

三、SceneManager对于获取场景的一些操作

（一） 
SceneManager 
class in UnityEngine.SceneManagement 
描述：运行时的场景管理。 
静态变量sceneCount: 当前加载的场景的总数。 
前加载的场景的数量将被返回。 
sceneCountInBuildSettings : 在BuildSettings的号码。

（二） 
CreateScene：在运行时创建一个空的新场景，使用给定的名称。 
在运行时创建一个空的新场景，使用给定的名称。 
新的场景将开放相加到层次与现有已经打开的场景。新场景的路径将是空的。此函数用于在运行时创建场景。创建一个场景编辑时间（例如，使编辑脚本或工具需要创建场景时），使用editorscenemanager.newscene。

（三） 
public static SceneManagement.Scene GetActiveScene() 
现场的活动场景。 
描述：获取当前活动场景。 
当前活动的场景将被用来作为目标由脚本实例化新的游戏对象现场。

 using UnityEngine;
 using UnityEngine.SceneManagement;

 public class GetActiveSceneExample : MonoBehaviour
 {
     void Start()
     {
         Scene scene = SceneManager.GetActiveScene();

         Debug.Log("Active scene is '" + scene.name + "'.");
     }
 }

（四） 
public static SceneManagement.Scene GetSceneAt(int index); 
index：场景索引。指数必须大于或等于0和小于scenemanager.scenecount。

返回： 
根据给定的参数返回一个场景引用。 
获取现场在添加场景的场景管理器的列表索引：

using UnityEditor;
using UnityEditor.SceneManagement;
using UnityEngine.SceneManagement;
using UnityEngine;
public class Example
{
    // adds a menu item which gives a brief summary of currently open scenes
    [MenuItem("SceneExample/Scene Summary")]
    public static void ListSceneNames()
    {
        string output = "";
        if (SceneManager.sceneCount > )
        {
            for (int n = ; n < SceneManager.sceneCount; ++n)
            {
                Scene scene = SceneManager.GetSceneAt(n);
                output += scene.name;
                output += scene.isLoaded ? " (Loaded, " : " (Not Loaded, ";
                output += scene.isDirty ? "Dirty, " : "Clean, ";
                output += scene.buildIndex >= ? " in build)\n" : " NOT in build)\n";
            }
        }
        else
        {
            output = "No open scenes.";
        }
        EditorUtility.DisplayDialog("Scene Summary",output, "Ok");
    }
}

（五）

public static SceneManagement.Scene GetActiveScene(); 
获取当前活动场景。 
当前活动的场景将被用来作为目标由脚本实例化新对象。

 using UnityEngine;
 using UnityEngine.SceneManagement;

 public class GetActiveSceneExample : MonoBehaviour
 {
     void Start()
     {
         Scene scene = SceneManager.GetActiveScene();

         Debug.Log("Active scene is '" + scene.name + "'.");
     }
 }

 public static void LoadScene(int sceneBuildIndex, SceneManagement.LoadSceneMode mode = LoadSceneMode.Single);
 public static void LoadScene(string sceneName, SceneManagement.LoadSceneMode mode = LoadSceneMode.Single);

sceneName: 需发加载的场景名称或路径。

sceneBuildIndex：在“ Build Settings”加载中的场景的索引。

Mode：允许您指定是否要加载相加现场。见LoadScene模式有关选项的详细信息。 
LoadSceneMode：在播放器加载一个场景时使用。 
Single：关闭所有当前场景和加载一个新场景。 
Additive：将场景添加到当前加载的场景中。 
你可以使用这个异步版本：LoadSceneAsync。

 using UnityEngine;
 using UnityEngine.SceneManagement;

 public class ExampleClass : MonoBehaviour {
     void Start () {
         // Only specifying the sceneName or sceneBuildIndex will load the scene with the Single mode
         SceneManager.LoadScene ("OtherSceneName", LoadSceneMode.Additive);
     }
 }

四、5.3的实现代码

上代码：

 /**************************************************************************
 Copyright:@maxdong
 Author: maxdong
 Date: 2017-07-04
 Description:加载关卡，可以分组加载和卸载。使用Unity版本为5.3.0.
 因为里面使用了场景管理的一个类，这个类在5.3.0以上版本才添加的。
 测试操作：使用空格键来切换场景，然后间隔5秒后才开始卸载。
 **************************************************************************/
 using UnityEngine;
 using System.Collections;
 using UnityEngine.SceneManagement;

 [System.Serializable]
 public class LevelOrder
 {

     [Header("每组关卡名称")]
     public string[] LevelNames;
 }

 public class ChangLevelsHasMain : MonoBehaviour
 {
     [Header("所有关卡列表")]
     public LevelOrder[] levelOrder;
     private static int index;
     private int totalLevels = ;
     private int levelOrderLength;

     void Start ()
     {
         for (int i = ; i < levelOrder.Length; i++)
         {
             totalLevels += levelOrder[i].LevelNames.Length;
         }

         if (totalLevels != SceneManager.sceneCountInBuildSettings)
         {

         }
         levelOrderLength = levelOrder.Length;
     }

     // Update is called once per frame
     void Update ()
     {
         if (Input.GetKeyDown(KeyCode.Space))
         {
             bool isOk = LoadNextLevels();
             if (isOk)
             {
                 InvokeRepeating("UnloadLastLevel", 2.0f, );
             }
         }
     }

     bool LoadNextLevels()
     {
         bool bResult = true;
         //index = index % levelOrderLength;
         if (index <  || index >= levelOrderLength)
         {
             bResult = false;
             return bResult;
         }

         int LoadTimes = levelOrder[index].LevelNames.Length;
         for (int i = ; i < LoadTimes; i++)
         {
             SceneManager.LoadSceneAsync(levelOrder[index].LevelNames[i], LoadSceneMode.Additive);
         }
         return bResult;
     }

     void UnloadLastLevel()
     {
         if (index == )
         {
             index++;
             CancelInvoke("UnloadLastLevel");
             return;
         }
         // 上一組的關卡
         int TmpLast = (index - ) >=  ? (index - ) : levelOrderLength - ;
         int LoadTimes = levelOrder[index].LevelNames.Length;
         for (int i = ; i < LoadTimes; i++)
         {
             Scene Tmp = SceneManager.GetSceneByName(levelOrder[index].LevelNames[i]);
             if (!Tmp.isLoaded)
             {
                 return;
             }
         }

         // 下一關卡全部加載完畢後，卸載之前關卡
         for (int i = ; i < levelOrder[TmpLast].LevelNames.Length; i++)
         {
             SceneManager.UnloadScene(levelOrder[TmpLast].LevelNames[i]);
         }
         index++;
         CancelInvoke("UnloadLastLevel");
     }
 }

就这样就可以了。 
代码主要是按组来加载关卡，然后按组来卸载。 
测试中，按下空格键来加载，每组关卡在一定时间后，（这里设置的5秒）自动卸载前一组关卡。这里主地图是不卸载的，会一直存在的。

怎么设置的呢？首先需要在Build setting中中把所有要处理的关卡放进来。要不就会在加载过程中报错。 
如下图： 

然后把代码挂在主地图的任意对象对象上就可以了.