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（转）【风宇冲】Unity3D教程宝典之AssetBundles:第一讲

分类: IT文章 • 2022-03-09 22:18:07

（转）【风宇冲】Unity3D教程宝典之AssetBundles:第一讲

自：http://blog.sina.com.cn/s/blog_471132920101gz8z.html

原创文章如需转载请注明：转载自风宇冲Unity3D教程学院

       
                                     AssetBundles第一讲：基本使用

AssetBundles是从unity导出你选择的assets,它使用特有的压缩格式并且应用可以实时去读取它。包括模型贴图音频等任何asset类型，甚至整个场景。压缩大小基本能达到zip的效果。AssetBundles从设计时就定位为可以很简单就下载到应用里。如果你想包括自定义的binary数据，就要用.bytes后缀，Unity将作为TextAssets导入他们。
 
注意:
AssetBundles并不像Unity官方说的那样，各种unity版本兼容。经测试在unity4中创建的ab,在4中正常使用，但在3.5.0里无法正常使用。说明用AB不能向下兼容。

开发阶段:
(1)创建AssetBundles:
不能是scene objects的objects使用BuildPipeline.BuildAssetBundle 
targetplatform要指定，不能用默认参数，默认模式是webplayer
 
  1. using UnityEngine;
  2. using UnityEditor;
  3. public class ExportAssetBundles {
  4.     [MenuItem("Assets/Build AssetBundle From Selection - Track dependencies")]
  5.     static void ExportResource () {
  6.         // Bring up save panel
  7.         string path = EditorUtility.SaveFilePanel ("Save Resource", "", "New Resource","unity3d");
  8.         if (path.Length != 0) {
  9.             // Build the resource file from the active selection.
  10.             Object[] selection = Selection.GetFiltered(typeof(Object), SelectionMode.DeepAssets);
  11.             BuildPipeline.BuildAssetBundle(Selection.activeObject, selection, 
  12. path, BuildAssetBundleOptions.CollectDependencies |BuildAssetBundleOptions.CompleteAssets
  13. ,BuildTarget.StandaloneWindows);
  14.             Selection.objects = selection;
  15.         }
  16.     }
  17.     [MenuItem("Assets/Build AssetBundle From Selection - No dependency tracking")]
  18.     static void ExportResourceNoTrack () {
  19.         // Bring up save panel
  20.         string path = EditorUtility.SaveFilePanel ("Save Resource", "", "New Resource","unity3d");
  21.         if (path.Length != 0) {
  22.             // Build the resource file from the active selection.
  23.             BuildPipeline.BuildAssetBundle(Selection.activeObject, Selection.objects, path);
  24.         }
  25.     }
  26. }
bool BuildPipeline.BuildAssetBundleExplicitAssetNames(Object[] assets, string[] assetName, string pathName, BuildAssetBundleOptions assetBundleOptions, Buildtarget targetPlatform)
创建bundle并自定义名称。assetName的长度及排列与assets对应。并不是真正改变物体的名称，只是在assetBundle.Load的时候有个唯一对应的名称
 

对上面代码仅需修改第11行。将BuildPipeline.BuildAssetBundle(Selection.activeObject, selection, 

path, BuildAssetBundleOptions.CollectDependencies | BuildAssetBundleOptions.CompleteAssets

,BuildTarget.StandaloneWindows); 里的第一个参数mainAsset去掉，并在selection也就是Object[]之后加string[] assetName即可

 
  1. [MenuItem("Assets/Build AssetBundle From Selection Names- Track dependencies")]
  2.     static void ExportResourceWithNames () {
  3.         // Bring up save panel
  4.         string path = EditorUtility.SaveFilePanel ("Save Resource", "", "New Resource","unity3d");
  5.         if (path.Length != 0) {
  6.             // Build the resource file from the active selection.
  7.             Object[] selection = Selection.GetFiltered(typeof(Object), SelectionMode.DeepAssets);
  8. string[] names = new string[selection.Length];
  9. for(int i =0;i
  10. {
  11. names[i] = i+"_"+ selection[i].name;
  12. }
  13.             BuildPipeline.BuildAssetBundleExplicitAssetNames( selection,names, 
  14. path, BuildAssetBundleOptions.CollectDependencies |BuildAssetBundleOptions.CompleteAssets
  15. ,BuildTarget.StandaloneWindows);
  16.             Selection.objects = selection;
  17.         }
  18.     }
 
 
 
 
  1. using System;
  2. using System.IO;
  3. using UnityEngine;
  5. public class LoadAssetBundle : MonoBehaviour {
  6. private AssetBundle assetBundle;
  7. private AssetBundleCreateRequest request;
  9. void Update () {
  10. }
  11. void OnGUI()
  12. {
  13. if(GUI.Button(new Rect(0,0,100,50),"Load"))
  14. {
  15. byte[] bs = File.ReadAllBytes(Application.dataPath+ "/withNames.unity3d");
  16. request = AssetBundle.CreateFromMemory(bs);
  17. }
  18. if(GUI.Button(new Rect(0,50,100,50),"Check"))
  19. {
  20. if(request.isDone == true)
  21. {
  22. assetBundle = request.assetBundle;
  23. UnityEngine.Object obj = assetBundle.Load("0_Cube");
  24. Instantiate(obj);
  25. }
  26. }
  27. }
将场景做成AB时，BuildPipeline.BuildStreamedSceneAssetBundle
将一个或者多个场景打包到asset bundle里，可以为任何平台，并总创建单一的压缩.unity3d文件。
在下载后，可以用WWW.LoadFromCacheOrDownload从缓存里读取。 
  1. using UnityEngine;
  2. using UnityEditor;
  4. public class BuildScene : MonoBehaviour {
  5. [MenuItem ("Build/BuildWebplayerStreamed")]
  6. static void BuildScenes()
  7. {
  8. string [] levels = new string[1];
  9. levels[0] = "Assets/scene.unity";
  10. BuildPipeline.BuildStreamedSceneAssetBundle(levels, "Assets/myLevel.unity3d",BuildTarget.StandaloneOSXIntel);
  11. }
  12. }


兼容性
Platform compatibility for AssetBundles
  Standalone Webplayer iOS Android
Editor Y Y Y Y
Standalone Y Y    
Webplayer Y Y    
iOS     Y  
Android       Y

(2)上传AssetBundles: 基于你所使用的服务器决定如何上传。

使用阶段：
(1)下载AssetBundles:
1 AssetBundle.CreateFromFile： 
   (1)只能用于pc和mac standalone
   (2)只支持Uncompressed：也就是在build的时候buildoption还要加上UncompressedAssetBundle 。
   (3)必须得是绝对路径。
       AssetBundle assetBundle = AssetBundle.CreateFromFile("D:/myBundle4.unity3d");

2 AssetBundle.CreateFromMemory(bs);

  1. using System;
  2. using System.IO;
  3. using UnityEngine;
  4. public class LoadAssetBundle : MonoBehaviour {
  5.     private AssetBundle assetBundle;
  6.     private AssetBundleCreateRequest request;
  7.     void Update () {
  8.         if(request!=null)
  9.             print(request.progress);
  10.     }
  11.    
  12.     void OnGUI()
  13.     {
  14.         if(GUI.Button(new Rect(0,0,100,50),"Load"))
  15.         {
  16.             byte[] bs = File.ReadAllBytes("D:/myBundle.unity3d");
  17.             request = AssetBundle.CreateFromMemory(bs);
  18.         }
  19.        
  20.        
  21.         if(GUI.Button(new Rect(0,50,100,50),"Check"))
  22.         {
  23.             if(request.isDone == true)
  24.             {
  25.                 print("name: "+request.assetBundle.mainAsset.name);
  26.                 Instantiate(request.assetBundle.mainAsset);
  27.             }
  28.         }
  29.     }
  30. }

3 AssetBundle bundle = www.assetBundle;
注：WWW也是可以读取本地文件的，
只需要在路径前file://即可，如
WWW myWWW = new WWW("file://E://LSY/wamp/www/cat.jpg");
  1. using System;
  2. using System.IO;
  3. using UnityEngine;
  4. using System.Collections;
  5. public class LoadAssetBundle : MonoBehaviour {
  6.     private AssetBundle assetBundle;
  7.     private string address = "http://127.0.0.1/AssetBundles/myBundle.unity3d";
  8.    
  9.     void OnGUI()
  10.     {
  11.         if(GUI.Button(new Rect(0,0,100,50),"Load web"))
  12.         {
  13.             StartCoroutine(Load());
  14.         }
  15.     }
  16.    
  17.     IEnumerator Load() {
  18.        // Download the file from the URL. It will not be saved in the Cache
  19.        string    AssetName="";
  20.        WWW www = new WWW(address);
  21.        yield return www;
  22.        if (www.error != null)
  23.            throw new Exception("WWW download had an error:" + www.error);
  24.        AssetBundle bundle = www.assetBundle;
  25.        if (AssetName == "")
  26.            Instantiate(bundle.mainAsset);
  27.        else
  28.            Instantiate(bundle.Load(AssetName));
  29.                // Unload the AssetBundles compressed contents to conserve memory
  30.                bundle.Unload(false);
  31.    }
  32. }
WWW.LoadFromCacheOrDownload
下载过程中可以更换下载地址,并保证版本一致, Webplayer的cache限制在50MB以内。
与普通的www下载仅仅是一句代码的区别
WWW www = new WWW(address);
WWW www = WWW.LoadFromCacheOrDownload(address,1);
  1. using System;
  2. using System.IO;
  3. using UnityEngine;
  4. using System.Collections;
  5. public class LoadAssetBundle : MonoBehaviour {
  6.     private AssetBundle assetBundle;
  7.     private string address = "http://127.0.0.1/AssetBundles/myBundle.unity3d";
  8.    
  9.     void OnGUI()
  10.     {
  11.         if(GUI.Button(new Rect(0,0,100,50),"Load web"))
  12.         {
  13.             StartCoroutine(Load());
  14.         }
  15.     }
  16.    
  17.     IEnumerator Load() {
  18.        string    AssetName="";
  19.        WWW www = WWW.LoadFromCacheOrDownload(address,1);
  20.        yield return www;
  21.        if (www.error != null)
  22.            throw new Exception("WWW download had an error:" + www.error);
  23.        AssetBundle bundle = www.assetBundle;
  24.        if (AssetName == "")
  25.            Instantiate(bundle.mainAsset);
  26.        else
  27.            Instantiate(bundle.Load(AssetName));
  28.                // Unload the AssetBundles compressed contents to conserve memory
  29.                bundle.Unload(false);
  30.    }
  31. }

(2)使用AssetBundles里的资源:
bool AssetBundle.Contains(string name) bundle中是否含有名为name的asset

Object AssetBundle.Load(string name) 读取bundle中名称为name的asset

Object AssetBundle.LoadAll()
UnityEngine.Object[] objs = assetBundle.LoadAll();
在本例中assetBundle.mainAsset是GameObject,但是并不代表assetBundle.LoadAll();的返回值数组的第一个数据是GameObject即obj[0]等于assetBundle.mainAsset
（转）【风宇冲】Unity3D教程宝典之AssetBundles:第一讲

assetBundle.mainAsset

AssetBundle.Unload（bool unloadAllLoadedObjects）
清空bundle里的所有资源。释放相关内存。清空后不能再通过该bundle创建物体。
unloadAllLoadedObjects为false: AssetBundle里的数据将会被释放，不影响已经scene中已经创建的相关物体。
unloadAllLoadedObjects为true: 不仅AssetBundle里的数据将会被释放，从该bundle创建的贴图材质等等asset将会被清空。如果scene中已经物体使用这些，连接将丢失。


（转）【风宇冲】Unity3D教程宝典之AssetBundles:第一讲

（转）【风宇冲】Unity3D教程宝典之AssetBundles:第一讲

 
读取场景:
当AssetBundle下载好后，直接Application.LoadLevel("scene");即可
 
  1. //******************************************************
  2. //AssetBundle.CreateFromMemory -> LoadLevel
  3. //******************************************************
  4. using System;
  5. using System.IO;
  6. using UnityEngine;
  8. public class LoadAssetBundle : MonoBehaviour {
  9. private AssetBundle assetBundle;
  10. private AssetBundleCreateRequest request;
  12. void Update () {
  13. }
  14. void OnGUI()
  15. {
  16. if(GUI.Button(new Rect(0,0,100,50),"Load"))
  17. {
  18. byte[] bs = File.ReadAllBytes(Application.dataPath+ "/myLevel.unity3d");
  19. request = AssetBundle.CreateFromMemory(bs);
  20. }
  21. if(GUI.Button(new Rect(0,50,100,50),"Check"))
  22. {
  23. if(request.isDone == true)
  24. {
  25. Application.LoadLevel("scene");
  26. }
  27. }
  28. }
  29. }
 
总结：
制作AssetBundle主要有
1 BuildPipeline.BuildAssetBundle 非场景
2 BuildPipeline.BuildStreamedSceneAssetBundle  场景
 
使用AssetBundle主要有
1 AssetBundle.CreateFromFile   只能是Uncompressed格式
2 AssetBundle.CreateFromMemory    需要处理request
3 AssetBundle bundle = www.assetBundle;  www又分为2种
  （1）WWW www = new WWW(address);
  （2）WWW www = WWW.LoadFromCacheOrDownload(address,1,crc);
          其中网游用的最多的是LoadFromCacheOrDownload，因为第一次下载后就存在本地缓存了，之后就直接从本地缓存读取.crc是用来做数据校验的。
 

其中推荐 LoadFromCacheOrDownload。不推荐CreateFromMemory，因为需要一个解析建AB结构的过程，比较耗时。CreateFromFile也不是很推荐，因为只支持非压缩格式，所以占容量比较多。

预制体打包成AssetBundle时：预制体可以搭脚本，并且指定关系等都可以照常使用。

要求：

(1)但是脚本必须是工程里有的

(2)AssetBundle里预制体上搭载的脚本必须和工程里的脚本一致。

否则会提示错误。

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