场景资源之解包（2）

本篇接着上一篇继续和大家分享场景资源这一主题，主要包括两个方面：

（1）加载场景

场景异步加载的代码比较简单，如下所示：

    private IEnumerator LoadLevelCoroutine()
    {
        string url = "ftp://127.0.0.1/TestScene.unity3d";
        int verNum = 1;

        WWW wwwForScene = WWW.LoadFromCacheOrDownload(url, verNum);
        while (wwwForScene.isDone == false)
            yield return null;

        AssetBundle bundle = wwwForScene.assetBundle;
        yield return Application.LoadLevelAsync("TestScene");
        wwwForScene.assetBundle.Unload(false);
    }

（2）加载场景物件

主要包含以下细分步骤：

a、下载并解析场景配表，得到场景物件信息。场景物件的数据结构如下所示：

public class XmlSceneGameobjectProp
{
    // Mesh信息
    public class MeshInfo
    {
        public string name;
        public string shader;

        public bool hasColor = false;
        public Vector4 color;

        public bool isStatic = true;
        public int lightmapIndex;
        public Vector4 lightmapTilingOffset;
    }

    public string name;
    public string group;
    // Transform信息
    public float posX, posY, posZ;
    public float rotX, rotY, rotZ;
    public float scaleX, scaleY, scaleZ;
    // Mesh列表，一个模型可以包含多个MeshRenderer
    public List LstMesh = new List();
}

xml解析的主体代码如下所示：

 private void ParseChildNode(XmlElement xmlGroup, XmlElement xmlChild)
    {
        SceneGameobjectProp newChild = new SceneGameobjectProp();
        newChild.group = xmlGroup.GetAttribute("name");
        newChild.name = xmlChild.GetAttribute("name");
        // 注册资源名字
        if (lstRes.Contains(newChild.name) == false)
        {
            lstRes.Add(newChild.name);
        }

        // Tranform节点
        XmlNode xmlTransform = xmlChild.SelectSingleNode("Transform");
        // MeshRenderer节点
        XmlNode xmlMeshRenderer = xmlChild.SelectSingleNode("MeshRenderer");

        if (xmlTransform != null && xmlTransform is XmlElement)
        {
            CXmlRead goReader = new CXmlRead(xmlTransform as XmlElement);
            newChild.posX = goReader.Float("posX", 0f);
            newChild.posY = goReader.Float("posY", 0f);
            newChild.posZ = goReader.Float("posZ", 0f);
            newChild.rotX = goReader.Float("rotX", 0f);
            newChild.rotY = goReader.Float("rotY", 0f);
            newChild.rotZ = goReader.Float("rotZ", 0f);
            newChild.scaleX = goReader.Float("scaleX", 1f);
            newChild.scaleY = goReader.Float("scaleY", 1f);
            newChild.scaleZ = goReader.Float("scaleZ", 1f);
        }

        if (xmlMeshRenderer != null && xmlMeshRenderer is XmlElement)
        {
            foreach (XmlNode node in xmlMeshRenderer.ChildNodes)
            {
                if ((node is XmlElement) == false)
                    continue;

                SceneGameobjectProp.MeshInfo mesh = new SceneGameobjectProp.MeshInfo();
                mesh.name = (node as XmlElement).GetAttribute("Mesh");
                mesh.shader = (node as XmlElement).GetAttribute("Shader");
                XmlNode xmlLightmap = node.SelectSingleNode("Lightmap");
                if (xmlLightmap != null && xmlLightmap is XmlElement)
                {
                    CXmlRead reader = new CXmlRead(xmlLightmap as XmlElement);
                    mesh.isStatic = reader.Bool("IsStatic", true);
                    mesh.lightmapIndex = reader.Int("LightmapIndex", -1);
                    mesh.lightmapTilingOffset = new Vector4(reader.Float("OffsetX", 0f), reader.Float("OffsetY", 0f), reader.Float("OffsetZ", 0f), reader.Float("OffsetW", 0f));
                }
                XmlNode xmlColor = node.SelectSingleNode("Color");
                if (xmlColor != null && xmlColor is XmlElement)
                {
                    CXmlRead reader = new CXmlRead(xmlColor as XmlElement);
                    mesh.hasColor = reader.Bool("hasColor", false);
                    mesh.color = new Vector4(reader.Float("r", 0f), reader.Float("g", 0f), reader.Float("b", 0f), reader.Float("a", 0f));
                }
                newChild.LstMesh.Add(mesh);
            }
        }

        lstGameObjectProp.Add(newChild);
    }

b、加载场景物件asset

同时开启多个Coroutine进行WWW的LoadFromCacheOrDownload操作，经测试开启的WWW线程越多，速度会越快，但是需要考虑实际的机器或平台的承载能力。

注意，我这儿的WWW操作是直接从缓存里面载入内存，而不是从网上下载。所有更新的游戏物件，可以在游戏开始的时候一次从网上Download到Cache，这样，在游戏过程中就不需要从网上Download资源了，wifi下载3G玩，爽歪歪~

如果一定要在此处从网上Download资源的话，线程数最好设为5个，很多平台有自己的限制，比如有的网页浏览器只能同时开6个等等......

    // 同时开启的Coroutine的数目
    private const int ThreadNum = 100;
    // 记录每个加载线程的进度，只有每个线程都加在结束了，场景加载才算完成
    private int[] arrThreadProggress = new int[ThreadNum];

    // 加载完成后的回掉
    public delegate void LoadFinishDelegate();
    public LoadFinishDelegate OnLoadFinish = null;
  
    // 需要下载的资源列表
    private List<string> lstRes = new List<string>();
    // 是否加载完毕的标记
    private bool hasFinished = false;

    private void LoadAsset()
    {for (int i = 0; i < ThreadNum; ++i)
        {
            CoroutineProvider.Instance().StartCoroutine(LoadAssetCoroutine(i));
        }
    }

    private IEnumerator LoadAssetCoroutine(int threadIndex)
    {
        while (arrThreadProggress[threadIndex] < lstRes.Count)
        {
            // 载入资源
            string name = lstRes[arrThreadProggress[threadIndex]];
            GameApp.GetResourceManager().LoadAsync(GlobalSetting.SceneAssetPath + name, typeof(GameObject));
            while (GameApp.GetResourceManager().IsResLoaded(GlobalSetting.SceneAssetPath + name) == false)
            {
                yield return null;
            }
            arrThreadProggress[threadIndex] += ThreadNum;
        }
        // 线程资源下载完毕，进行加载回掉
        if (IsLoadFinished() && hasFinished == false)
        {
            hasFinished = true;if (OnLoadFinish != null)
            {
                OnLoadFinish();
            }
        }
    }

上面的黑体标出的代码是是实际的加载代码，具体实现已经在帖子“AssetBundle系列——资源的加载、简易的资源管理器”中讲解过了，此处不再赘述。

c、实例化场景物件

　　// 实例化
    GameObject goIns = GameObject.Instantiate(asset) as GameObject;
    goIns.name = goProp.name;

    // 设置父节点
    GameObject goGroup = null;
    dicGroupGameobject.TryGetValue(goProp.group, out goGroup);
    if (goGroup != null)
        goIns.transform.parent = goGroup.transform;
    else
        goIns.transform.parent = goRoot.transform;

    // 设置Transform
    goIns.transform.position = new Vector3(goProp.posX, goProp.posY, goProp.posZ);
    goIns.transform.eulerAngles = new Vector3(goProp.rotX, goProp.rotY, goProp.rotZ);
    goIns.transform.localScale = new Vector3(goProp.scaleX, goProp.scaleY, goProp.scaleZ);

    // 设置Shader、Lightmap
    int index = 0;
    int meshCount = goProp.LstMesh.Count;
    foreach (MeshRenderer mr in goIns.gameObject.GetComponentsInChildren(true))
    {
        if (mr.material != null)
        {
            if (index < meshCount)
            {
                SceneGameobjectProp.MeshInfo meshProp = goProp.LstMesh[index];
                mr.material.shader = Shader.Find(meshProp.shader);
                if (meshProp.hasColor)
                    mr.material.color = meshProp.color;
                bool isStatic = meshProp.isStatic;
                mr.gameObject.isStatic = isStatic;
                if (isStatic)
                {
                    mr.lightmapIndex = meshProp.lightmapIndex;
                    mr.lightmapTilingOffset = meshProp.lightmapTilingOffset;
                }
            }
            index++;
        }
    }