unity动态加载obj文件

unity2018.4.2f1

vs2017

最近项目需求，需要实现动态读物外部obj模型，并加载到场景中，研究了好几天，终于实现了，在此做个记录。

1、首先随便找个.obj模型，带贴图，我的资源截图如下：

.mtl文件是负责记录模型与贴图的对应关系

obj问价与mtl文件均可以用记事本打开，查看内部数据

obj文件截图：

mtllib Tifa.mtl 记录当前obj文件对应的mtl文件的名称（一个mtl文件可以包含多个材质）

v:模型顶点数据

vt:模型顶点纹理坐标数据

vn:模型顶点法线数据

usemtl diss_00.png 表示当前模型分组使用的材质，每一个模型分组以usemtl 开始（一个模型存在有多个子物体的情况）

比如我这个：

mtl文件截图：

newmtl diss_00.png：表示当前的材质名称

illum：照明度（0-10）

kd:当前材质的散射光

ka:当前材质的环境光

ks:当前材质的镜面光

ke:当前材质的散射光

Ns:材质的光亮度

map_Kd:当前材质对应的贴图名称

2、根据模型文本文件分析，编写模型数据结构，直接上代码

ObjPart：obj文件数据结构

using System.Collections;
using System.Collections.Generic;
using UnityEngine;public class ObjPart
{/// <summary>/// 材质名称/// </summary>public string strMatName;/// <summary>/// UV坐标数组/// </summary>public List<Vector2> listUV; //vt/// <summary>/// 法线数组/// </summary>public List<Vector3> listNormal;//vn/// <summary>/// 切线数组/// </summary>public List<Vector4> listTangent;/// <summary>/// 顶点数组/// </summary>public List<Vector3> listVertex; //v/// <summary>/// 面数组 面索引/// </summary>public List<int> listTriangle;public ObjPart(){strMatName = "";listUV = new List<Vector2>();listNormal = new List<Vector3>();listVertex = new List<Vector3>();listTriangle = new List<int>();listTangent = new List<Vector4>();}
}

ObjMatItem：mtl文件数据结构

using System.Collections;
using System.Collections.Generic;
using UnityEngine;//mtl数据结构（记录的是材质对应的贴图）
public class ObjMatItem 
{/// <summary>/// 材质名称/// </summary>public string strMatName;public int illum;public Vector3 Kd;public Vector3 Ka;public Vector3 Tf;public Vector2 widthHeight;public string map_Kd;public float Ni;public ObjMatItem(){strMatName = "";illum = -1;Kd = new Vector3(0.0f, 0.0f, 0.0f);Ka = new Vector3(0.0f, 0.0f, 0.0f);Tf = new Vector3(0.0f, 0.0f, 0.0f);map_Kd = "";Ni = 1.0f;widthHeight.x = 0.0f;widthHeight.y = 0.0f;}
}

ObjModel：模型数据结构

using System.Collections;
using System.Collections.Generic;
using UnityEngine;/// <summary>
/// 完整模型=网格+材质
/// </summary>
public class ObjModel 
{public List<ObjPart> objParts;   //网格public List<ObjMatItem> ObjMats; //材质
}

3、从文本文件中加载obj数据以及mtl数据

ObjMesh：负责从.obj文件中加载数据

using System;
using System.Collections;
using System.Collections.Generic;
using System.IO;
using UnityEngine;/// <summary>
/// 负责从.obj文件中加载数据
/// </summary>
public class ObjMesh 
{/// <summary>/// UV坐标列表/// </summary>private List<Vector3> uvArrayList;/// <summary>/// 法线列表/// </summary>private List<Vector3> normalArrayList;/// <summary>/// 顶点列表/// </summary>private List<Vector3> vertexArrayList;public List<ObjPart> listObjParts;public List<ObjMatItem> listObjMats;public string _strMatPath { get; set; }public string _strObjPath { get; set; }public string _strObjName { get; set; }/// <summary>/// 构造函数    /// </summary>public ObjMesh(){//初始化列表uvArrayList = new List<Vector3>();normalArrayList = new List<Vector3>();vertexArrayList = new List<Vector3>();listObjParts = new List<ObjPart>();listObjMats = new List<ObjMatItem>();_strMatPath = _strObjName = "";}/// <summary>/// 从一个文本化后的.obj文件中加载模型/// </summary>public ObjMesh LoadFromObj(string strObjPath){_strObjPath = strObjPath;_strObjName = strObjPath;_strObjName = _strObjName.Replace("/", "");//读取内容if (!File.Exists(strObjPath)) return null;StreamReader reader = new StreamReader(strObjPath, System.Text.Encoding.Default);string objText = reader.ReadToEnd();reader.Close();if (objText.Length <= 0)return null;//v这一行在3dsMax中导出的.obj文件//  前面是两个空格后面是一个空格objText = objText.Replace("  ", " ");//将文本化后的obj文件内容按行分割string[] allLines = objText.Split('\n');foreach (string line in allLines){//将每一行按空格分割char[] charsToTrim = { ' ' };string[] chars = line.TrimEnd('\r').TrimStart(' ').Split(charsToTrim, StringSplitOptions.RemoveEmptyEntries);if (chars.Length <= 0){continue;}//根据第一个字符来判断数据的类型switch (chars[0]){case "mtllib":_strMatPath = _strObjPath.Substring(0, _strObjPath.LastIndexOf('/') + 1) + chars[1];break;case "v"://处理顶点this.vertexArrayList.Add(new Vector3(-(ConvertToFloat(chars[1])),ConvertToFloat(chars[2]),ConvertToFloat(chars[3])));break;case "vn"://处理法线this.normalArrayList.Add(new Vector3(-ConvertToFloat(chars[1]),ConvertToFloat(chars[2]),ConvertToFloat(chars[3])));break;case "vt"://处理UVthis.uvArrayList.Add(new Vector3(ConvertToFloat(chars[1]),ConvertToFloat(chars[2])));break;case "usemtl":ObjPart objPart = new ObjPart();objPart.strMatName = chars[1];//材质名称listObjParts.Add(objPart);break;case "f"://处理面GetTriangleList(chars);break;}}//获取mtl文件路径// string mtlFilePath = strObjPath.Replace(".obj", ".mtl");if (_strMatPath != ""){LoadMat(_strMatPath);}return this;}private void LoadMat(string strmtlPath){//从mtl文件中加载材质listObjMats = ObjMaterial.Instance.LoadFormMtl(strmtlPath);}/// <summary>/// 获取面列表./// </summary>/// <param name="chars">Chars.</param>/// private List<Vector3> indexVectorList = new List<Vector3>();private Vector3 indexVector = new Vector3(0, 0);private void GetTriangleList(string[] chars){indexVectorList.Clear();for (int i = 1; i < chars.Length; ++i){//将每一行按照空格分割后从第一个元素开始//按照/继续分割可依次获得顶点索引、法线索引和UV索引string[] indexs = chars[i].Split('/');Vector3 vertex = (Vector3)vertexArrayList[ConvertToInt(indexs[0]) - 1];listObjParts[listObjParts.Count - 1].listVertex.Add(vertex);indexVector = new Vector3(0, 0);//UV索引if (indexs.Length > 1){if (indexs[1] != "")indexVector.y = ConvertToInt(indexs[1]);}//法线索引if (indexs.Length > 2){if (indexs[2] != "")indexVector.z = ConvertToInt(indexs[2]);}//给UV数组赋值if (uvArrayList.Count > 0 && indexVector.y > 0.01){Vector3 tVec = (Vector3)uvArrayList[(int)indexVector.y - 1];listObjParts[listObjParts.Count - 1].listUV.Add(new Vector2(tVec.x, tVec.y));}//给法线数组赋值if (normalArrayList.Count > 0 && indexVector.z > 0.01){Vector3 nVec = (Vector3)normalArrayList[(int)indexVector.z - 1];listObjParts[listObjParts.Count - 1].listNormal.Add(nVec);}//将索引向量加入列表中indexVectorList.Add(indexVector);}//面索引int nCount = listObjParts[listObjParts.Count - 1].listVertex.Count - indexVectorList.Count; //nCount==0 3 6 9 indexVectorList.Count=3 三角形面//Debug.Log(indexVectorList.Count);for (int j = 1; j < indexVectorList.Count - 1; ++j){//按照0,1,2这样的方式来组成面          listObjParts[listObjParts.Count - 1].listTriangle.Add(nCount);listObjParts[listObjParts.Count - 1].listTriangle.Add(nCount + j);listObjParts[listObjParts.Count - 1].listTriangle.Add(nCount + j + 1);}}/// <summary>/// 将一个字符串转换为浮点类型/// </summary>/// <param name="s">待转换的字符串</param>/// <returns></returns>private float ConvertToFloat(string s){//return (float)System.Convert.ToDouble(s,CultureInfo.InvariantCulture);float fValue = 0.0f;try{fValue = (float)Convert.ToDouble(s);}catch (Exception ex){Debug.LogError("数据[" + s + "]转换失败! " + ex.Message);}return fValue;}/// <summary>/// 将一个字符串转化为整型 /// </summary>/// <returns>待转换的字符串</returns>/// <param name="s"></param>private int ConvertToInt(string s){//return System.Convert.ToInt32(s, CultureInfo.InvariantCulture);int nValue = 0;try{nValue = Convert.ToInt32(s);}catch (Exception ex){Debug.LogError("数据[" + s + "]转换失败! " + ex.Message);}return nValue;}
}

ObjMaterial：负责从.mtl中加载数据

using System;
using System.Collections;
using System.Collections.Generic;
using System.IO;
using UnityEngine;/// <summary>
/// 负责从.mtl中加载数据
/// </summary>
public class ObjMaterial
{/// <summary>/// 当前实例/// </summary>private static ObjMaterial instance=new ObjMaterial();public static ObjMaterial Instance{get{if (instance == null)instance = new ObjMaterial();//GameObject.FindObjectOfType<ObjMaterial>(); return instance;}}/// <summary>/// 从一个文本化后的mtl文件加载一组材质/// </summary>/// <param name="mtlText">文本化的mtl文件</param>/// <param name="texturePath">贴图文件夹路径</param>public List<ObjMatItem> LoadFormMtl(string strMtlText){List<ObjMatItem> listObjMats = new List<ObjMatItem>();DirectoryInfo mtlParent=Directory.GetParent(Settings.ObjPath);if (!File.Exists(mtlParent + "\\" + strMtlText)) return null;Stream mtlStream = new FileStream(mtlParent+"\\"+ strMtlText,FileMode.Open);//mtl文件与obj文件处于同一级目录下StreamReader reader = new StreamReader(mtlStream);string mtlText = reader.ReadToEnd();reader.Close();if (mtlText == "")return listObjMats;//将文本化后的内容按行分割string[] allLines = mtlText.Split('\n');foreach (string line in allLines){//按照空格分割每一行的内容string[] chars = line.TrimEnd('\r').TrimStart(' ').Split(' ');switch (chars[0]){case "newmtl"://处理材质名ObjMatItem matItem = new ObjMatItem();matItem.strMatName = chars[1];listObjMats.Add(matItem);//根据贴图创建材质球break;case "Ka":listObjMats[listObjMats.Count - 1].Ka = new Vector3(ConvertToFloat(chars[1]),ConvertToFloat(chars[2]),ConvertToFloat(chars[3]));break;case "Kd"://处理漫反射listObjMats[listObjMats.Count - 1].Kd = new Vector3(ConvertToFloat(chars[1]),ConvertToFloat(chars[2]),ConvertToFloat(chars[3]));break;case "Ks"://暂时仅考虑漫反射break;case "Ke"://Todobreak;case "Tf"://处理漫反射listObjMats[listObjMats.Count - 1].Tf = new Vector3(ConvertToFloat(chars[1]),ConvertToFloat(chars[2]),ConvertToFloat(chars[3]));break;case "Ni":listObjMats[listObjMats.Count - 1].Ni = ConvertToFloat(chars[1]);break;case "e"://Todobreak;case "illum":listObjMats[listObjMats.Count - 1].illum = Convert.ToInt32(chars[1]);break;case "map_Ka"://暂时仅考虑漫反射break;case "map_Kd"://处理漫反射贴图string textureName = chars[1].Substring(chars[1].LastIndexOf("\\") + 1, chars[1].Length - chars[1].LastIndexOf("\\") - 1);listObjMats[listObjMats.Count - 1].map_Kd = textureName;break;case "map_Ks"://暂时仅考虑漫反射break;}}GameObject.Find("Canvas").GetComponent<LoadModel>().CreatMaterial(listObjMats);return listObjMats;}/// <summary>/// 将一个字符串转换为浮点类型/// </summary>/// <param name="s">待转换的字符串</param>/// <returns></returns>private float ConvertToFloat(string s){return System.Convert.ToSingle(s);}}

Settings：记录数据

using System.Collections;
using System.Collections.Generic;
using UnityEngine;public class Settings
{public static string ObjPath=null;           //模型路径public static Dictionary<string, Material> ModelMaterialList = new Dictionary<string, Material>();//材质球存储 key:材质名称 value：材质球
}

4、开始使用获得的文件数据，在场景中加载模型

LoadModel：创建模型（该脚本挂载到canvas上，由按钮触发LoadModelEvent函数开始创建模型）

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.Networking;
using System;
using System.IO;public class LoadModel : MonoBehaviour
{private List<ObjMesh> listObjModel = new List<ObjMesh>();private List<ObjMatItem> listObjMats = new List<ObjMatItem>();private List<ObjPart> listObjParts = new List<ObjPart>();private GameObject goParent;public GameObject _gameObj;    //模型父节点private bool isDone = false;    //true：材质球全部创建完成后 给模型贴材质//按钮事件处理public void LoadModelEvent(){string strObjPath = "C:\\Users\\123\\Desktop\\obj__001\\123\\飞马\\飞马 .obj";Settings.ObjPath = strObjPath;ObjMesh objInstace = new ObjMesh();objInstace = objInstace.LoadFromObj(strObjPath);if (objInstace == null) return;listObjModel.Add(objInstace);listObjParts = objInstace.listObjParts;//模型Debug.Log("Parts:" + listObjParts.Count);listObjMats = objInstace.listObjMats;  //材质if(listObjMats!=null)Debug.Log("Mats:" + listObjMats.Count);string strGameName = strObjPath;strGameName = strGameName.Replace("/", "");string[] names = strGameName.Split('\\');strGameName = names[names.Length - 1];goParent = new GameObject(strGameName); //模型资源名称StartCoroutine(WaitLoadMaterialTexture());}IEnumerator WaitLoadMaterialTexture(){while (!isDone&& listObjMats!=null) //等待材质创建完成{yield return null;}//计算网格int i = 0;foreach (ObjPart part in listObjParts){++i;Mesh mesh = new Mesh();mesh.vertices = part.listVertex.ToArray();//顶点//mesh.triangles = part.listTriangle.ToArray();mesh.triangles= ResetTriangles(part.listTriangle.ToArray());//修改三角形面 翻转三角形面if (part.listUV.Count > 0){mesh.uv = part.listUV.ToArray();}if (part.listNormal.Count > 0){mesh.normals = part.listNormal.ToArray();}mesh.tangents = part.listTangent.ToArray(); //切线mesh.RecalculateBounds();// mesh.RecalculateNormals(); //法线//生成物体GameObject go = new GameObject(part.strMatName + i.ToString());// ==go.AddComponent<ObjDestroy>();MeshFilter meshFilter = go.AddComponent<MeshFilter>();meshFilter.mesh = mesh;//parts里面存储的有材质名称 根据材质名称生成材质球MeshRenderer render = go.AddComponent<MeshRenderer>();RenderAddMaterials(go, part);go.transform.SetParent(goParent.transform);}goParent.transform.SetParent(_gameObj.transform);}//翻转法线private Vector3[] FlipNormals(Vector3[] normals){Vector3[] res=new Vector3[normals.Length];for (int i = 0; i < normals.Length; i++){normals[i] = -normals[i];}return normals;}//翻转三角形面片private int[] ResetTriangles(int[] triangles){for (int i = 0; i < triangles.Length; i+=3){int t = triangles[i];triangles[i] = triangles[i + 2];triangles[i + 2] = t;}return triangles;}private void RenderAddMaterials(GameObject go, ObjPart part){//给模型添加材质球if (Settings.ModelMaterialList.ContainsKey(part.strMatName)){go.GetComponent<MeshRenderer>().material = Settings.ModelMaterialList[part.strMatName];}}//创建所有需要的材质球(mtl文件与obj文件读取完成后，调用)public void CreatMaterial(List<ObjMatItem> matList){int nowIndex = 0;foreach (ObjMatItem item in matList){++nowIndex;string textureName = item.map_Kd;//贴图名称string texturePath = Directory.GetParent(Settings.ObjPath).FullName + "\\" + textureName;StartCoroutine(LoadTexture(item, nowIndex, matList.Count));}}/// <summary>/// 加载贴图   /// </summary>IEnumerator LoadTexture(ObjMatItem item, int nowIndex, int maxIndex){string texturePath = Directory.GetParent(Settings.ObjPath).FullName + "\\" + item.map_Kd;  //图片路径string matName = item.strMatName;//材质名称if (!File.Exists(texturePath)) { yield break; } //终止协成UnityWebRequest request = new UnityWebRequest(texturePath);DownloadHandlerTexture tex = new DownloadHandlerTexture(true);request.downloadHandler = tex;yield return request.SendWebRequest();if (!request.isNetworkError){Texture2D texture = tex.texture;       //下载的东西不用时要清空 否则内存占用会越来越多TODOMaterial material = new Material(Shader.Find("Standard"));material.mainTexture = texture;Settings.ModelMaterialList.Add(matName, material);if (nowIndex == maxIndex){isDone = true;}}else{Debug.LogError("load texture failed!");}}
}

5、实现过程中遇到的困难

首先脚本数据结构以及文件读取都是从网上找的，然后结合自己的实际需求稍作修改。

比如mtl文件、obj文件以及贴图都在同一路径，所以读取路径拼接方式全部都改了；

模型材质加载是自己加上去的，根据mtl文件创建对应的材质球，存储起来，模型的子节点根据材质名称选择贴哪个材质；

其中最大的问题是模型网格面反了，导致贴上贴图后模型看起来是透明的，问了老大，说可能是法线反了，改了没效果，就百度下mesh的知识，看了下网格加载部分的代码，注意到加载顶点以及法线时vector3的第一个数据取反了，如下图所示：