[Unity] unity5.3 assetbundle打包及加载

　　Unity5.3更新了assetbundle的打包和加载api，下面简单介绍使用方法及示例代码。

　　在Unity中选中一个prefab查看Inspector窗口，有两个位置可以进行assetbundle的标记。

　　第一个为assetBundleName，如果这里不是None，则这个资源会记录到AssetDatabase里，使用BuildAssetBundles打包时，会自动将AssetBundleName一致的资源打到一个包中。

　　第二个为Variant，可用于区分不同分辨率的资源。如果在abName=S的情况下，variant有None也有HD，打ab包时会报错，如果variant有指定，则同一abName的资源的variant不能为None。

     

// 此api用于打包所有标记了AssetBundleName的资源

public static AssetBundleManifest BuildAssetBundles(

　　string outputPath,

　　BuildAssetBundleOptions assetBundleOptions = BuildAssetBundleOptions.None,

　　BuildTarget targetPlatform = BuildTarget.WebPlayer

);

// 此api用于打包指定的资源

public static AssetBundleManifestBuildAssetBundles(

　　string outputPath,

　　AssetBundleBuild[] builds,

　　BuildAssetBundleOptionsassetBundleOptions = BuildAssetBundleOptions.None,

　　BuildTargettargetPlatform = BuildTarget.WebPlayer

);

　　其中，AssetBundleBuild数组参数，用于指定资源，AssetBundleBuild有三个属性，分别指定assetBundleName，variant，资源路径等。

 

 

　　以下为打包及加载部分代码：大部分参考了雨凇MOMO的文章《UGUI研究院之全面理解图集与使用（三）》，做了部分修改。

 #define USE_ASSETBUNDLE

 using UnityEngine;
 using System.Collections;
 using UnityEngine.UI;
 using UnityEditor.VersionControl;

 public class UIMain : MonoBehaviour{

     AssetBundle assetbundle = null;
     void Start ()
     {
         CreatImage(loadSprite("flag_blue"));
         CreatImage(loadSprite("flag_yellow"));
     }

     private void CreatImage(GameObject gobj ){
         Sprite sprite = gobj.GetComponent<SpriteRenderer>().sprite as Sprite;
         GameObject go = new GameObject(sprite.name);
         go.layer = LayerMask.NameToLayer("UI");
         go.transform.parent = transform;
         go.transform.localScale= Vector3.one;
         Image image = go.AddComponent<Image>();
         image.sprite = sprite;
         image.SetNativeSize();
     }

     private GameObject loadSprite(string spriteName){
         #if USE_ASSETBUNDLE
         if(assetbundle == null)
             assetbundle = AssetBundle.LoadFromFile(Application.streamingAssetsPath +"/flagbundle");
         return assetbundle.LoadAsset(spriteName) as GameObject;
         #else
         return Resources.Load<GameObject>("Sprite/" + spriteName);
         #endif
     }

 }

UIMain

 using UnityEngine;
 using System.Collections;
 using System.Collections.Generic;
 using UnityEditor;
 using System.IO;
 using UnityEditor.VersionControl;

 public class AltasMaker : MonoBehaviour {

     [MenuItem ("MyMenu/AtlasMaker")]
     static private void MakeAtlas()
     {
         string spriteDir = Application.dataPath + "/Resources/Sprite";
         Debug.Log("spriteDir : " + spriteDir);
         if(!Directory.Exists(spriteDir)){
             Directory.CreateDirectory(spriteDir);
         }

         DirectoryInfo rootDirInfo = new DirectoryInfo (Application.dataPath + "/Atlas");
         foreach (DirectoryInfo dirInfo in rootDirInfo.GetDirectories()) {
             foreach (FileInfo pngFile in dirInfo.GetFiles("*.png", SearchOption.AllDirectories)) {
                 string allPath = pngFile.FullName;
                 Debug.Log("allPath1 : " + allPath);
                 string assetPath = allPath.Substring(allPath.IndexOf("Assets"));
                 Debug.Log("assetPath : " + assetPath);
                 Sprite sprite = AssetDatabase.LoadAssetAtPath<Sprite>(assetPath);
                 GameObject go = new GameObject(sprite.name);
                 go.AddComponent<SpriteRenderer>().sprite = sprite;
                 allPath = spriteDir+ "/" +sprite.name+ ".prefab";
                 Debug.Log("allPath2 : " + allPath);
                 string prefabPath = allPath.Substring(allPath.IndexOf("Assets"));
                 PrefabUtility.CreatePrefab(prefabPath, go);
                 GameObject.DestroyImmediate(go);
             }
         }
     }

     [MenuItem ("MyMenu/Build Assetbundle")]
     static private void BuildAssetBundle()
     {
         string outputdir = Application.dataPath + "/StreamingAssets";

         if(!Directory.Exists(outputdir))
         {
             Directory.CreateDirectory(outputdir);
         }

         DirectoryInfo rootDirInfo = new DirectoryInfo (Application.dataPath + "/Atlas");
         foreach (DirectoryInfo dirInfo in rootDirInfo.GetDirectories()) {
             List<Sprite> assets = new List<Sprite>();

             foreach (FileInfo pngFile in dirInfo.GetFiles("*.png", SearchOption.AllDirectories))
             {
                 string allPath = pngFile.FullName;
                 string assetPath = allPath.Substring(allPath.IndexOf("Assets"));
                 assets.Add(AssetDatabase.LoadAssetAtPath<Sprite>(assetPath));
             }

             AssetBundleBuild[] buildMap  = new AssetBundleBuild[];

             buildMap[].assetBundleName = dirInfo.Name + "bundle"; // 想定义的任何名称
             string[] spriteNames = new string[assets.Count];
             for(int i = ; i < assets.Count; i++)
             {
                 spriteNames[i] = "Assets/Atlas/" + dirInfo.Name + "/" + assets[i].name + ".png"; // 注意路径写全
             }
             buildMap[].assetNames = spriteNames;
             buildMap[].assetBundleVariant = null;

             BuildPipeline.BuildAssetBundles(
                 outputdir,  // output path
                 buildMap,  // build bundles info
                 BuildAssetBundleOptions.UncompressedAssetBundle,  // options
                 GetBuildTarget()); // build target
         }
     }

     [MenuItem ("MyMenu/Build All AssetBundles")]
     static private void BuildAllAssetBundles()
     {
         BuildPipeline.BuildAssetBundles(
             Application.dataPath + "/StreamingAssets",  // output path
             BuildAssetBundleOptions.ChunkBasedCompression,  // options
             GetBuildTarget());
     }

     static private BuildTarget GetBuildTarget()
     {
         BuildTarget target = BuildTarget.WebPlayer;
         #if UNITY_STANDALONE
         target = BuildTarget.StandaloneOSXIntel64;
         #elif UNITY_IPHONE
         target = BuildTarget.iPhone;
         #elif UNITY_ANDROID
         target = BuildTarget.Android;
         #endif
         return target;
     }
 }

AltasMaker

　　注：1 经过验证，同一个资源如果没有改变，不会被重新build

　　　　2 如果缓存文件不刷新，强制调用Caching.CleanCache()。

　　assetbundle有三种压缩格式：默认为LZMA模式（最小），还有LZ4和不压缩（最大）。

　　不同压缩格式相关优缺点及使用详见下文：Unity5.x新的AssetBundle机制02——压缩

其他参考：

1 UGUI研究院之全面理解图集与使用（三）

2 【厚积薄发】揭开Unity AssetBundle庐山真面目（二）

3 Unity3D 5.3 新版AssetBundle使用方案及策略

4 AssetDatabase