unity导出.obj模型文件

unity导出.obj模型文件

最近使用realworldterrain生成真实地形遇到一个问题，就是该地形的坐标轴没有在中心位置，这样在旋转缩放操作时候就有各种问题，效果不好，于是想到先导出该地形为obj文件，然后在Max中修改其坐标轴位置。

一、将地形导出为obj文件

在unity中新建js脚本ExportTerrain.js，且必须放在Assets文件夹下的Editor文件夹中。（js文件不要用vs编译，要用自带的mono编译器。）

import System.IO;
    import System.Text;

    enum SaveFormat {Triangles, Quads}
    enum SaveResolution {Full, Half, Quarter, Eighth, Sixteenth}

    class ExportTerrain extends EditorWindow 
    {
        var saveFormat = SaveFormat.Triangles;
        var saveResolution = SaveResolution.Half;
        static var terrain : TerrainData;
        static var terrainPos : Vector3;

        var tCount : int;
        var counter : int;
        var totalCount : int;

        @MenuItem ("Terrain/Export To Obj...")
        static function Init () 
        {
            terrain = null;
        var terrainObject : Terrain = Selection.activeObject as Terrain;
            if (!terrainObject) 
            {
            terrainObject = Terrain.activeTerrain;
            }
            if (terrainObject) 
            {
                terrain = terrainObject.terrainData;
                terrainPos = terrainObject.transform.position;
            }
            EditorWindow.GetWindow(ExportTerrain).Show();
        }

        function OnGUI () 
        {
        if (!terrain) 
        {
                GUILayout.Label("No terrain found");
                if (GUILayout.Button("Cancel")) 
                {
                    EditorWindow.GetWindow(ExportTerrain).Close();
                }
            return;
         }
            saveFormat = EditorGUILayout.EnumPopup("Export Format", saveFormat);
        saveResolution = EditorGUILayout.EnumPopup("Resolution", saveResolution);

            if (GUILayout.Button("Export")) 
            {
                Export();
            }
        }

        function Export () 
        {
            var fileName = EditorUtility.SaveFilePanel("Export .obj file", "", "Terrain", "obj");
        var w = terrain.heightmapWidth;
            var h = terrain.heightmapHeight;
            var meshScale = terrain.size;
            var tRes = Mathf.Pow(2, parseInt(saveResolution));
            meshScale = Vector3(meshScale.x/(w-1)*tRes, meshScale.y, meshScale.z/(h-1)*tRes);
            var uvScale = Vector2(1.0/(w-1), 1.0/(h-1));
            var tData = terrain.GetHeights(0, 0, w, h);

            w = (w-1) / tRes + 1;
            h = (h-1) / tRes + 1;
        var tVertices = new Vector3[w * h];
            var tUV = new Vector2[w * h];
            if (saveFormat == SaveFormat.Triangles) 
            {
                var tPolys = new int[(w-1) * (h-1) * 6];
            }
            else 
            {
            tPolys = new int[(w-1) * (h-1) * 4];
            }

            // Build vertices and UVs
            for (y = 0; y < h; y++) 
            {
                for (x = 0; x < w; x++) 
                {
                    tVertices[y*w + x] = Vector3.Scale(meshScale, Vector3(x, tData[x*tRes,y*tRes], y)) + terrainPos;
                    tUV[y*w + x] = Vector2.Scale(Vector2(x*tRes, y*tRes), uvScale);
                }
            }

        var index = 0;
            if (saveFormat == SaveFormat.Triangles) 
            {
                // Build triangle indices: 3 indices into vertex array for each triangle
                for (y = 0; y < h-1; y++) 
                {
                    for (x = 0; x < w-1; x++) 
                    {
                        // For each grid cell output two triangles
                        tPolys[index++] = (y     * w) + x;
                        tPolys[index++] = ((y+1) * w) + x;
                        tPolys[index++] = (y     * w) + x + 1;

                    tPolys[index++] = ((y+1) * w) + x;
                        tPolys[index++] = ((y+1) * w) + x + 1;
                    tPolys[index++] = (y     * w) + x + 1;
                    }
                }
            }
            else 
            {
                // Build quad indices: 4 indices into vertex array for each quad
                for (y = 0; y < h-1; y++) 
                {
                    for (x = 0; x < w-1; x++) 
                    {
                        // For each grid cell output one quad
                        tPolys[index++] = (y     * w) + x;
                        tPolys[index++] = ((y+1) * w) + x;
                        tPolys[index++] = ((y+1) * w) + x + 1;
                        tPolys[index++] = (y     * w) + x + 1;
                    }
                }  
            }

        // Export to .obj
            try 
            {
                var sw = new StreamWriter(fileName);
                sw.WriteLine("# Unity terrain OBJ File");

                // Write vertices
                System.Threading.Thread.CurrentThread.CurrentCulture = new System.Globalization.CultureInfo("en-US");
                counter = tCount = 0;
            totalCount = (tVertices.Length*2 + (saveFormat == SaveFormat.Triangles? tPolys.Length/3 : tPolys.Length/4)) / 1000;
                for (i = 0; i < tVertices.Length; i++) 
                {
                    UpdateProgress();
                    var sb = StringBuilder("v ", 20);
                // StringBuilder stuff is done this way because it's faster than using the "{0} {1} {2}"etc. format
                    // Which is important when you're exporting huge terrains.
                    sb.Append(tVertices[i].x.ToString()).Append(" ").
                       Append(tVertices[i].y.ToString()).Append(" ").
                       Append(tVertices[i].z.ToString());
                    sw.WriteLine(sb);
                }
                // Write UVs
            for (i = 0; i < tUV.Length; i++) 
            {
                    UpdateProgress();
                sb = StringBuilder("vt ", 22);
                    sb.Append(tUV[i].x.ToString()).Append(" ").
                       Append(tUV[i].y.ToString());
                    sw.WriteLine(sb);
                }
                if (saveFormat == SaveFormat.Triangles) 
                {
                // Write triangles
                    for (i = 0; i < tPolys.Length; i += 3) 
                    {
                        UpdateProgress();
                    sb = StringBuilder("f ", 43);
                        sb.Append(tPolys[i]+1).Append("/").Append(tPolys[i]+1).Append(" ").
                           Append(tPolys[i+1]+1).Append("/").Append(tPolys[i+1]+1).Append(" ").
                           Append(tPolys[i+2]+1).Append("/").Append(tPolys[i+2]+1);
                        sw.WriteLine(sb);
                    }
                }
                else 
                {
                    // Write quads
                    for (i = 0; i < tPolys.Length; i += 4) 
                    {
                        UpdateProgress();
                        sb = StringBuilder("f ", 57);
                        sb.Append(tPolys[i]+1).Append("/").Append(tPolys[i]+1).Append(" ").
                           Append(tPolys[i+1]+1).Append("/").Append(tPolys[i+1]+1).Append(" ").
                           Append(tPolys[i+2]+1).Append("/").Append(tPolys[i+2]+1).Append(" ").
                           Append(tPolys[i+3]+1).Append("/").Append(tPolys[i+3]+1);
                        sw.WriteLine(sb);
                    }      
                }
            }
            catch (err) 
            {
                Debug.Log("Error saving file: " + err.Message);
            }
        sw.Close();

            terrain = null;
            EditorUtility.ClearProgressBar();
            EditorWindow.GetWindow(ExportTerrain).Close();
        }

        function UpdateProgress () 
        {
            if (counter++ == 1000) 
            {
                counter = 0;
                EditorUtility.DisplayProgressBar("Saving...", "", Mathf.InverseLerp(0, totalCount, ++tCount));
            }
        }   
  }  

然后在菜单栏中会多出一项“Terrain”，选中场景中的地形，然后点击该菜单栏，就可以导出了，导出的地形文件为obj类型，将obj导入max中，选择“仅影响轴”即可改变坐标轴位置。