Unity导出stl格式

stl是常用的3D打印格式，目前有不少文章介绍stl的，这里不多介绍。
导出stl分为ascii形式和二进制形式，区别在于ascii可以直接用文本文件打开查看，而二进制直接打开是乱码，但是二进制形式读写速度较快，生成的文件也比ascii要小很多。

开发环境

unity：2018.2.16 2019.3.15
模型查看工具：Meshlab2020.09 、 CAD Assistant
测试模型：assetstore 上的 office building

核心模块

ASCII形式 将单个mesh写出为stl

     /// <summary>/// 将单个mesh数据使用StreamWrite写出为stl/// </summary>/// <param name="mesh">待导出的mesh</param>/// <param name="sw">输出流</param>/// <param name="trans">mesh对应的transform，用于将顶点法线转到世界空间</param>/// <param name="exchangeCoordinate">是否需要变换坐标手系，unity是左手坐标系，默认变换到右手坐标系</param>private static void ExportMeshToStl(Mesh mesh, StreamWriter sw, Transform trans, bool exchangeCoordinate = true){for (int j = 0; j < mesh.subMeshCount; j++){int[] tris;if (mesh.subMeshCount == 1){sw.Write("\nsolid " + mesh.name + "\n");tris = mesh.triangles;}else{sw.Write("\nsolid " + mesh.name + "_" + j + "\n");tris = mesh.GetIndices(j);}Vector3[] vertices = mesh.vertices;Vector3[] normals = mesh.normals;for (int i = 0; i < tris.Length / 3; i++){//法线变换到世界空间Vector3 nor1 = trans.TransformDirection(normals[tris[i * 3]]);Vector3 nor2 = trans.TransformDirection(normals[tris[i * 3 + 1]]);Vector3 nor3 = trans.TransformDirection(normals[tris[i * 3 + 2]]);//顶点变换到世界空间Vector3 worldPos1 = trans.TransformPoint(vertices[tris[i * 3]]);Vector3 worldPos2 = trans.TransformPoint(vertices[tris[i * 3 + 1]]);Vector3 worldPos3 = trans.TransformPoint(vertices[tris[i * 3 + 2]]);//如果需要从左手系变换到右手系if (exchangeCoordinate){nor1.x *= -1;nor2.x *= -1;nor3.x *= -1;worldPos1.x *= -1;worldPos2.x *= -1;worldPos3.x *= -1;}Vector3 normal = (nor1 + nor2 + nor3) / 3;sw.Write("\tfacet normal " + normal.x + " " + normal.y + " " + normal.z);sw.Write("\n\t\touter loop\n");sw.Write("\t\t\tvertex " + worldPos1.x + " " + worldPos1.y + " " + worldPos1.z + "\n");if (exchangeCoordinate){sw.Write("\t\t\tvertex " + worldPos3.x + " " + worldPos3.y + " " + worldPos3.z + "\n");sw.Write("\t\t\tvertex " + worldPos2.x + " " + worldPos2.y + " " + worldPos2.z + "\n");}else{sw.Write("\t\t\tvertex " + worldPos2.x + " " + worldPos2.y + " " + worldPos2.z + "\n");sw.Write("\t\t\tvertex " + worldPos3.x + " " + worldPos3.y + " " + worldPos3.z + "\n");}sw.Write("\t\tendloop\n");sw.Write("\tendfacet\n");}if (mesh.subMeshCount == 1){sw.Write("endsolid " + mesh.name);}else{sw.Write("endsolid " + mesh.name + "_" + j);}}}

二进制形式 将单个mesh写出为stl

     /// <summary>/// 将单个mesh数据使用StreamWrite写出为stl,二进制格式/// </summary>/// <param name="mesh">待导出的mesh</param>/// <param name="bw">BinaryWriter 写出二进制数据的类</param>/// <param name="trans">mesh对应的transform，用于将顶点法线转到世界空间</param>/// <param name="exchangeCoordinate">是否需要变换坐标手系，unity是左手坐标系，默认变换到右手坐标系</param>private static void ExportMeshToStl(Mesh mesh, BinaryWriter bw, Transform trans, bool exchangeCoordinate = true){Vector3[] vertices = mesh.vertices;Vector3[] normals = mesh.normals;int[] tris = mesh.triangles;//每个三角面片固定占用50个字节for (int i = 0; i < tris.Length / 3; i++){Vector3 nor1 = trans.TransformDirection(normals[tris[i * 3]]);Vector3 nor2 = trans.TransformDirection(normals[tris[i * 3 + 1]]);Vector3 nor3 = trans.TransformDirection(normals[tris[i * 3 + 2]]);Vector3 worldPos1 = trans.TransformPoint(vertices[tris[i * 3]]);Vector3 worldPos2 = trans.TransformPoint(vertices[tris[i * 3 + 1]]);Vector3 worldPos3 = trans.TransformPoint(vertices[tris[i * 3 + 2]]);if (exchangeCoordinate){nor1.x *= -1;nor2.x *= -1;nor3.x *= -1;worldPos1.x *= -1;worldPos2.x *= -1;worldPos3.x *= -1;}Vector3 normal = (nor1 + nor2 + nor3) / 3;bw.Write(normal.x);bw.Write(normal.y);bw.Write(normal.z);bw.Write(worldPos1.x);bw.Write(worldPos1.y);bw.Write(worldPos1.z);if (exchangeCoordinate){bw.Write(worldPos3.x);bw.Write(worldPos3.y);bw.Write(worldPos3.z);bw.Write(worldPos2.x);bw.Write(worldPos2.y);bw.Write(worldPos2.z);}else{bw.Write(worldPos2.x);bw.Write(worldPos2.y);bw.Write(worldPos2.z);bw.Write(worldPos3.x);bw.Write(worldPos3.y);bw.Write(worldPos3.z);}//填充两个字节  三角面片的最后2个字节用来描述三角面片的属性信息(包括颜色属性等)暂时没有用bw.Seek(2, SeekOrigin.Current);}}

完整代码

/****************************************************文件：Exporter.cs作者：TKB邮箱: 544726237@qq.com日期：2021/7/24 23:9:12功能：导出stl
*****************************************************/using System;
using System.Collections.Generic;
using System.IO;
using System.Text;
using UnityEngine;namespace TLib
{public class Exporter{#region 导出stl/// <summary>/// 导出Transfrom及其子mesh为单个stl/// </summary>/// <param name="trans">待导出的transfrom</param>/// <param name="outputPath">导出的stl完整路径，如D:/TKB/output.stl</param>/// <param name="exchangeCoordinate">是否要变换坐标系，从左手坐标系（unity）变换到右手坐标系，默认为true</param>/// <param name="isBinary">是否以格式导出</param>public static void ExportStl(Transform trans, string outputPath, bool exchangeCoordinate = true, bool isBinary = true){ExportStl(trans.gameObject, outputPath, exchangeCoordinate, isBinary);}/// <summary>/// 导出GameObject及其子mesh为单个stl/// </summary>/// <param name="go">待导出的GameObject</param>/// <param name="outputPath">导出的stl完整路径，如D:/TKB/output.stl</param>/// <param name="exchangeCoordinate">是否要变换坐标系，从左手坐标系（unity）变换到右手坐标系，默认为true</param>/// <param name="isBinary">是否以格式导出</param>public static void ExportStl(GameObject go, string outputPath, bool exchangeCoordinate = true, bool isBinary = true){if (!go) return;if (!Directory.Exists(Path.GetDirectoryName(outputPath))){Directory.CreateDirectory(Path.GetDirectoryName(outputPath));}if (File.Exists(outputPath)){try{File.Delete(outputPath);Debug.LogWarning("该路径已存在同名文件，已删除！" + outputPath);}catch (Exception e){Debug.LogError(e + "该路径已存在同名文件并且删除失败！" + outputPath);return;}}MeshFilter[] meshFilters = go.GetComponentsInChildren<MeshFilter>();SkinnedMeshRenderer[] skinnedMeshRenderers = go.GetComponentsInChildren<SkinnedMeshRenderer>();int meshCount = meshFilters.Length + skinnedMeshRenderers.Length;try{FileStream meshFS = new FileStream(outputPath, FileMode.Create, FileAccess.Write, FileShare.ReadWrite); ;StreamWriter meshSW = null;BinaryWriter meshBW = null;if (!isBinary){meshSW = new StreamWriter(meshFS, Encoding.UTF8);}else{meshBW = new BinaryWriter(meshFS, Encoding.UTF8);//文件的起始80字节是文件头存储零件名，可以放入任何文字信息meshBW.Write(go.name);meshBW.Seek(80, SeekOrigin.Begin);//紧随着用4个字节的整数来描述实体的三角面片个数int count = 0;for (int i = 0; i < meshFilters.Length; i++){Mesh mesh;
#if UNITY_EDITORmesh = meshFilters[i].sharedMesh;#elsemesh = meshFilters[i].mesh;
#endifcount += mesh.triangles.Length;}for (int i = 0; i < skinnedMeshRenderers.Length; i++){Mesh mesh;
#if UNITY_EDITORmesh = skinnedMeshRenderers[i].sharedMesh;#elsemesh = meshFilters[i].mesh;
#endifcount += mesh.triangles.Length;}meshBW.Write(count/3);}for (int i = 0; i < meshFilters.Length; i++){Mesh mesh;
#if UNITY_EDITORmesh = meshFilters[i].sharedMesh;UnityEditor.EditorUtility.DisplayProgressBar("导出Stl", mesh.name + ":" + i + "/" + meshCount, i * 1.0f / meshCount);
#elsemesh = meshFilters[i].mesh;
#endifif (!isBinary)ExportMeshToStl(mesh, meshSW, meshFilters[i].transform, exchangeCoordinate);elseExportMeshToStl(mesh, meshBW, meshFilters[i].transform, exchangeCoordinate);}for (int i = 0; i < skinnedMeshRenderers.Length; i++){Mesh mesh;
#if UNITY_EDITORmesh = skinnedMeshRenderers[i].sharedMesh;UnityEditor.EditorUtility.DisplayProgressBar("导出Stl", mesh.name + ":" + (i + meshFilters.Length) + "/" + meshCount, i * 1.0f / meshCount);
#elsemesh = meshFilters[i].mesh;
#endifif (!isBinary)ExportMeshToStl(mesh, meshSW, skinnedMeshRenderers[i].transform, exchangeCoordinate);elseExportMeshToStl(mesh, meshBW, skinnedMeshRenderers[i].transform, exchangeCoordinate);}if (!isBinary){meshSW.Close();}else{meshBW.Close();}meshFS.Close();}catch (Exception e){Debug.LogError(e);}finally{UnityEditor.EditorUtility.ClearProgressBar();}}/// <summary>/// 将Transform及其子对象导出为多个stl，每个mesh对应一个/// </summary>/// <param name="trans">待导出的Transform</param>/// <param name="outputDir">导出的文件夹路径，stl存放的位置</param>/// <param name="exchangeCoordinate">是否要变换坐标系，从左手坐标系（unity）变换到右手坐标系，默认为true</param>///  <param name="isBinary">是否以格式导出</param>public static void ExportStls(Transform trans, string outputDir, bool exchangeCoordinate = true, bool isBinary = true){ExportStls(trans.gameObject, outputDir, exchangeCoordinate, isBinary);}/// <summary>///  将GameObject及其子对象导出为多个stl，每个mesh对应一个/// </summary>/// <param name="go">待导出的GameObject</param>/// <param name="outputDir">导出的文件夹路径，stl存放的位置</param>/// <param name="exchangeCoordinate">是否要变换坐标系，从左手坐标系（unity）变换到右手坐标系，默认为true</param>///  <param name="isBinary">是否以格式导出</param>public static void ExportStls(GameObject go, string outputDir, bool exchangeCoordinate = true, bool isBinary = true){if (!Directory.Exists(outputDir)) Directory.CreateDirectory(outputDir);MeshFilter[] meshFilters = go.GetComponentsInChildren<MeshFilter>();SkinnedMeshRenderer[] skinnedMeshRenderers = go.GetComponentsInChildren<SkinnedMeshRenderer>();Dictionary<string, int> meshNameDic = new Dictionary<string, int>();int meshCount = meshFilters.Length + skinnedMeshRenderers.Length;for (int i = 0; i < meshFilters.Length; i++){try{string name = meshFilters[i].gameObject.name;if (meshNameDic.ContainsKey(name)){meshNameDic[name]++;name += meshNameDic[name];}else meshNameDic.Add(name, 0);string stlPath = Path.Combine(outputDir, name + ".stl");FileStream meshFS = new FileStream(stlPath, FileMode.Create, FileAccess.Write, FileShare.ReadWrite);StreamWriter meshSW = null;BinaryWriter meshBW = null;Mesh mesh;
#if UNITY_EDITORmesh = meshFilters[i].sharedMesh;UnityEditor.EditorUtility.DisplayProgressBar("导出Stl", mesh.name + ":" + i + "/" + meshCount, i * 1.0f / meshCount);
#elsemesh = meshFilters[i].mesh;
#endifif (!isBinary){meshSW = new StreamWriter(meshFS, Encoding.UTF8);ExportMeshToStl(mesh, meshSW, meshFilters[i].transform, exchangeCoordinate);meshSW.Close();}else{meshBW = new BinaryWriter(meshFS, Encoding.UTF8);//文件的起始80字节是文件头存储零件名，可以放入任何文字信息meshBW.Write(name);meshBW.Seek(80, SeekOrigin.Begin);meshBW.Write(mesh.triangles.Length / 3);ExportMeshToStl(mesh, meshBW, meshFilters[i].transform, exchangeCoordinate);meshBW.Close();}meshFS.Close();}catch (Exception e){Debug.LogError(e);}}for (int i = 0; i < skinnedMeshRenderers.Length; i++){try{string name = skinnedMeshRenderers[i].gameObject.name;if (meshNameDic.ContainsKey(name)){name += meshNameDic[name];meshNameDic[name]++;}else meshNameDic.Add(name, 1);string stlPath = Path.Combine(outputDir, name + ".stl");FileStream meshFS = new FileStream(stlPath, FileMode.Create, FileAccess.Write, FileShare.ReadWrite);StreamWriter meshSW = null;BinaryWriter meshBW = null;Mesh mesh;
#if UNITY_EDITORmesh = skinnedMeshRenderers[i].sharedMesh;UnityEditor.EditorUtility.DisplayProgressBar("导出Stl", mesh.name + ":" + (i + meshFilters.Length) + "/" + meshCount, i * 1.0f / meshCount);
#elsemesh = meshFilters[i].mesh;
materials;
#endifif (!isBinary){meshSW = new StreamWriter(meshFS, Encoding.UTF8);ExportMeshToStl(mesh, meshSW, skinnedMeshRenderers[i].transform, exchangeCoordinate);meshSW.Close();}else{meshBW = new BinaryWriter(meshFS, Encoding.UTF8);//文件的起始80字节是文件头存储零件名，可以放入任何文字信息meshBW.Write(name);meshBW.Seek(80, SeekOrigin.Begin);meshBW.Write(mesh.triangles.Length / 3);ExportMeshToStl(mesh, meshBW, skinnedMeshRenderers[i].transform, exchangeCoordinate);meshBW.Close();}meshFS.Close();}catch (Exception e){Debug.LogError(e);}}UnityEditor.EditorUtility.ClearProgressBar();}/// <summary>/// 将单个mesh数据使用StreamWrite写出为stl/// </summary>/// <param name="mesh">待导出的mesh</param>/// <param name="sw">输出流</param>/// <param name="trans">mesh对应的transform，用于将顶点法线转到世界空间</param>/// <param name="exchangeCoordinate">是否需要变换坐标手系，unity是左手坐标系，默认变换到右手坐标系</param>private static void ExportMeshToStl(Mesh mesh, StreamWriter sw, Transform trans, bool exchangeCoordinate = true){for (int j = 0; j < mesh.subMeshCount; j++){int[] tris;if (mesh.subMeshCount == 1){sw.Write("\nsolid " + mesh.name + "\n");tris = mesh.triangles;}else{sw.Write("\nsolid " + mesh.name + "_" + j + "\n");tris = mesh.GetIndices(j);}Vector3[] vertices = mesh.vertices;Vector3[] normals = mesh.normals;for (int i = 0; i < tris.Length / 3; i++){Vector3 nor1 = trans.TransformDirection(normals[tris[i * 3]]);Vector3 nor2 = trans.TransformDirection(normals[tris[i * 3 + 1]]);Vector3 nor3 = trans.TransformDirection(normals[tris[i * 3 + 2]]);Vector3 worldPos1 = trans.TransformPoint(vertices[tris[i * 3]]);Vector3 worldPos2 = trans.TransformPoint(vertices[tris[i * 3 + 1]]);Vector3 worldPos3 = trans.TransformPoint(vertices[tris[i * 3 + 2]]);if (exchangeCoordinate){nor1.x *= -1;nor2.x *= -1;nor3.x *= -1;worldPos1.x *= -1;worldPos2.x *= -1;worldPos3.x *= -1;}Vector3 normal = (nor1 + nor2 + nor3) / 3;sw.Write("\tfacet normal " + normal.x + " " + normal.y + " " + normal.z);sw.Write("\n\t\touter loop\n");sw.Write("\t\t\tvertex " + worldPos1.x + " " + worldPos1.y + " " + worldPos1.z + "\n");if (exchangeCoordinate){sw.Write("\t\t\tvertex " + worldPos3.x + " " + worldPos3.y + " " + worldPos3.z + "\n");sw.Write("\t\t\tvertex " + worldPos2.x + " " + worldPos2.y + " " + worldPos2.z + "\n");}else{sw.Write("\t\t\tvertex " + worldPos2.x + " " + worldPos2.y + " " + worldPos2.z + "\n");sw.Write("\t\t\tvertex " + worldPos3.x + " " + worldPos3.y + " " + worldPos3.z + "\n");}sw.Write("\t\tendloop\n");sw.Write("\tendfacet\n");}if (mesh.subMeshCount == 1){sw.Write("endsolid " + mesh.name);}else{sw.Write("endsolid " + mesh.name + "_" + j);}}}/// <summary>/// 将单个mesh数据使用StreamWrite写出为stl,二进制格式/// </summary>/// <param name="mesh">待导出的mesh</param>/// <param name="bw">BinaryWriter 写出二进制数据的类</param>/// <param name="trans">mesh对应的transform，用于将顶点法线转到世界空间</param>/// <param name="exchangeCoordinate">是否需要变换坐标手系，unity是左手坐标系，默认变换到右手坐标系</param>private static void ExportMeshToStl(Mesh mesh, BinaryWriter bw, Transform trans, bool exchangeCoordinate = true){Vector3[] vertices = mesh.vertices;Vector3[] normals = mesh.normals;int[] tris = mesh.triangles;//每个三角面片固定占用50个字节for (int i = 0; i < tris.Length / 3; i++){Vector3 nor1 = trans.TransformDirection(normals[tris[i * 3]]);Vector3 nor2 = trans.TransformDirection(normals[tris[i * 3 + 1]]);Vector3 nor3 = trans.TransformDirection(normals[tris[i * 3 + 2]]);Vector3 worldPos1 = trans.TransformPoint(vertices[tris[i * 3]]);Vector3 worldPos2 = trans.TransformPoint(vertices[tris[i * 3 + 1]]);Vector3 worldPos3 = trans.TransformPoint(vertices[tris[i * 3 + 2]]);if (exchangeCoordinate){nor1.x *= -1;nor2.x *= -1;nor3.x *= -1;worldPos1.x *= -1;worldPos2.x *= -1;worldPos3.x *= -1;}Vector3 normal = (nor1 + nor2 + nor3) / 3;bw.Write(normal.x);bw.Write(normal.y);bw.Write(normal.z);bw.Write(worldPos1.x);bw.Write(worldPos1.y);bw.Write(worldPos1.z);if (exchangeCoordinate){bw.Write(worldPos3.x);bw.Write(worldPos3.y);bw.Write(worldPos3.z);bw.Write(worldPos2.x);bw.Write(worldPos2.y);bw.Write(worldPos2.z);}else{bw.Write(worldPos2.x);bw.Write(worldPos2.y);bw.Write(worldPos2.z);bw.Write(worldPos3.x);bw.Write(worldPos3.y);bw.Write(worldPos3.z);}//填充两个字节  三角面片的最后2个字节用来描述三角面片的属性信息(包括颜色属性等)暂时没有用bw.Seek(2, SeekOrigin.Current);}}}#endregion
}

测试脚本

/****************************************************文件：ExportStlExample.cs作者：TKB邮箱: 544726237@qq.com日期：2021/7/26 22:19:56功能：编辑器环境测试将选中的物体导出stl
*****************************************************/using UnityEngine;namespace TLib
{public class ExportStlExample{
#if UNITY_EDITOR//将当前选中的物体下所有mesh导出到一个stl中[UnityEditor.MenuItem("Tools/导出stl", false)]private static void OnClickExportObj(){GameObject go = UnityEditor.Selection.activeObject as GameObject;Exporter.ExportStl(go.transform, Application.dataPath +"/"+ go.name+".stl",true,false);UnityEditor.AssetDatabase.Refresh();}//将当前选中的物体下的mesh分别导出为stl[UnityEditor.MenuItem("Tools/导出stls", false)]private static void OnClickExportObj1(){GameObject go = UnityEditor.Selection.activeObject as GameObject;Exporter.ExportStls(go, Application.dataPath + "/Exports");UnityEditor.AssetDatabase.Refresh();}
#endif}
}

效果

unity中的模型截图：

选择导出为stl 在meshlab中的截图：

选择导出为stls时导出了3000+的模型：

注意

这个测试模型导出二进制格式时使用meshlab打开报错，但是用CAD Assistant可以打开，原因还不清楚

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