【风宇冲】Unity3D教程宝典之AssetBundles:第一讲

浏览数：55 / 时间：2015年06月08日

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

using UnityEngine;
using UnityEditor;
public class ExportAssetBundles {
[MenuItem("Assets/Build AssetBundle From Selection - Track dependencies")]
static void ExportResource () {
// Bring up save panel
string path = EditorUtility.SaveFilePanel ("Save Resource", "", "New Resource","unity3d");
if (path.Length != 0) {
// Build the resource file from the active selection.
Object[] selection = Selection.GetFiltered(typeof(Object), SelectionMode.DeepAssets);
BuildPipeline.BuildAssetBundle(Selection.activeObject, selection,
path, BuildAssetBundleOptions.CollectDependencies |BuildAssetBundleOptions.CompleteAssets
,BuildTarget.StandaloneWindows);
Selection.objects = selection;
}
}
[MenuItem("Assets/Build AssetBundle From Selection - No dependency tracking")]
static void ExportResourceNoTrack () {
// Bring up save panel
string path = EditorUtility.SaveFilePanel ("Save Resource", "", "New Resource","unity3d");
if (path.Length != 0) {
// Build the resource file from the active selection.
BuildPipeline.BuildAssetBundle(Selection.activeObject, Selection.objects, path);
}
}
}

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

[MenuItem("Assets/Build AssetBundle From Selection Names- Track dependencies")]
static void ExportResourceWithNames () {
// Bring up save panel
string path = EditorUtility.SaveFilePanel ("Save Resource", "", "New Resource","unity3d");
if (path.Length != 0) {
// Build the resource file from the active selection.
Object[] selection = Selection.GetFiltered(typeof(Object), SelectionMode.DeepAssets);
string[] names = new string[selection.Length];
for(int i =0;i
{
names[i] = i+"_"+ selection[i].name;
}
BuildPipeline.BuildAssetBundleExplicitAssetNames( selection,names,
path, BuildAssetBundleOptions.CollectDependencies |BuildAssetBundleOptions.CompleteAssets
,BuildTarget.StandaloneWindows);
Selection.objects = selection;
}
}

using System;
using System.IO;
using UnityEngine;
public class LoadAssetBundle : MonoBehaviour {
private AssetBundle assetBundle;
private AssetBundleCreateRequest request;
void Update () {
}
void OnGUI()
{
if(GUI.Button(new Rect(0,0,100,50),"Load"))
{
byte[] bs = File.ReadAllBytes(Application.dataPath+ "/withNames.unity3d");
request = AssetBundle.CreateFromMemory(bs);
}
if(GUI.Button(new Rect(0,50,100,50),"Check"))
{
if(request.isDone == true)
{
assetBundle = request.assetBundle;
UnityEngine.Object obj = assetBundle.Load("0_Cube");
Instantiate(obj);
}
}
}

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。

using UnityEngine;
using UnityEditor;
public class BuildScene : MonoBehaviour {
[MenuItem ("Build/BuildWebplayerStreamed")]
static void BuildScenes()
{
string [] levels = new string[1];
levels[0] = "Assets/scene.unity";
BuildPipeline.BuildStreamedSceneAssetBundle(levels, "Assets/myLevel.unity3d",BuildTarget.StandaloneOSXIntel);
}
}

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);

using System;
using System.IO;
using UnityEngine;
public class LoadAssetBundle : MonoBehaviour {
private AssetBundle assetBundle;
private AssetBundleCreateRequest request;
void Update () {
if(request!=null)
print(request.progress);
}
void OnGUI()
{
if(GUI.Button(new Rect(0,0,100,50),"Load"))
{
byte[] bs = File.ReadAllBytes("D:/myBundle.unity3d");
request = AssetBundle.CreateFromMemory(bs);
}
if(GUI.Button(new Rect(0,50,100,50),"Check"))
{
if(request.isDone == true)
{
print("name: "+request.assetBundle.mainAsset.name);
Instantiate(request.assetBundle.mainAsset);
}
}
}
}

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");

using System;
using System.IO;
using UnityEngine;
using System.Collections;
public class LoadAssetBundle : MonoBehaviour {
private AssetBundle assetBundle;
private string address = "http://127.0.0.1/AssetBundles/myBundle.unity3d";
void OnGUI()
{
if(GUI.Button(new Rect(0,0,100,50),"Load web"))
{
StartCoroutine(Load());
}
}
IEnumerator Load() {
// Download the file from the URL. It will not be saved in the Cache
string AssetName="";
WWW www = new WWW(address);
yield return www;
if (www.error != null)
throw new Exception("WWW download had an error:" + www.error);
AssetBundle bundle = www.assetBundle;
if (AssetName == "")
Instantiate(bundle.mainAsset);
else
Instantiate(bundle.Load(AssetName));
// Unload the AssetBundles compressed contents to conserve memory
bundle.Unload(false);
}
}

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);

using System;
using System.IO;
using UnityEngine;
using System.Collections;
public class LoadAssetBundle : MonoBehaviour {
private AssetBundle assetBundle;
private string address = "http://127.0.0.1/AssetBundles/myBundle.unity3d";
void OnGUI()
{
if(GUI.Button(new Rect(0,0,100,50),"Load web"))
{
StartCoroutine(Load());
}
}
IEnumerator Load() {
string AssetName="";
WWW www = WWW.LoadFromCacheOrDownload(address,1);
yield return www;
if (www.error != null)
throw new Exception("WWW download had an error:" + www.error);
AssetBundle bundle = www.assetBundle;
if (AssetName == "")
Instantiate(bundle.mainAsset);
else
Instantiate(bundle.Load(AssetName));
// Unload the AssetBundles compressed contents to conserve memory
bundle.Unload(false);
}
}

(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

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。