Open CASCADE学习|保存为STL文件

STL (Stereolithography) 文件是一种广泛用于3D打印和计算机辅助设计 (CAD) 领域的文件格式。它描述了一个三维模型的表面而不包含颜色、材质或其他非几何信息。STL文件通常用于3D打印过程中，因为它们仅包含构建物体所需的位置信息。

由于STL文件只包含表面信息，因此在导出过程中可能会丢失一些细节，特别是当模型具有非常小的特征或内部几何结构时。因此，在导出之前，最好确保你的模型是“水密的”（即没有内部孔或洞），并且所有的细节都在可接受的打印分辨率内。

为了将一个3D模型保存为STL文件，你通常需要使用一个3D建模软件或CAD软件，如SolidWorks、Fusion 360、Blender、Tinkercad等。

下面基于OCCT实现将3D模型保存为STL文件：

void SaveFile(const QString filename)
{std::fstream fs;fs.open(filename.toStdString(), std::ios::out);bool flag = fs.is_open();
fs << "solid OCC STL\n";TopoDS_Shape aBottle = MakeBottle(50, 70, 30);IMeshTools_Parameters aMeshParams;  //离散化的参数BRepMesh_IncrementalMesh::SetParallelDefault(true);for (TopExp_Explorer Ex(aBottle, TopAbs_FACE); Ex.More(); Ex.Next()){TopoDS_Face aFace = TopoDS::Face(Ex.Current());//划分网格BRepMesh_IncrementalMesh aMesher(aFace, aMeshParams);const Standard_Integer aStatus = aMesher.GetStatusFlags();//读取网格TopLoc_Location  loc = aFace.Location();const  Poly_ListOfTriangulation triangulars = BRep_Tool::Triangulations(aFace, loc); //容器int num = triangulars.Size();
Poly_ListOfTriangulation::iterator iter = triangulars.begin();for (iter; iter != triangulars.end(); iter++) {Handle(Poly_Triangulation) poy = *iter;Standard_Integer nodNum = poy->NbTriangles();bool f = poy->HasNormals();for (int i = 1; i <= nodNum; i++) {Poly_Triangle tri = poy->Triangle(i);
Standard_Integer n1, n2, n3;tri.Get(n1, n2, n3); //得到三角形三个顶点编号
//计算三角形面片的法线double x1 = poy->Node(n1).X();double y1 = poy->Node(n1).Y();double z1 = poy->Node(n1).Z();
double x2 = poy->Node(n2).X();double y2 = poy->Node(n2).Y();double z2 = poy->Node(n2).Z();
double x3 = poy->Node(n3).X();double y3 = poy->Node(n3).Y();double z3 = poy->Node(n3).Z();
double detX1 = x2 - x1;double detY1 = y2 - y1;double detZ1 = z2 - z1;
double detX2 = x3 - x2;double detY2 = y3 - y2;double detZ2 = z3 - z2;
double X = detY1 * detZ2 - detZ1 * detY2;double Y = detZ1 * detX2 - detX1 * detZ2;double Z = detX1 * detY2 - detY1 * detX2;
double module = std::pow(X * X + Y * Y + Z * Z, 0.5);X /= module;Y /= module;Z /= module;
//gp_Dir normal = poy->Normal(i);
fs << " facet normal  " << X << " " << Y << " " << Z << "\n";fs << "  outer loop" << "\n";fs << "   vertex  " << poy->Node(n1).X() << " " << poy->Node(n1).Y() << " " << poy->Node(n1).Z() << "\n";//std::cout<< "   vertex  " << poy->Node(n1).X() << " " << poy->Node(n1).Y() << " " << poy->Node(n1).Z() << "\n";fs << "   vertex  " << poy->Node(n2).X() << " " << poy->Node(n2).Y() << " " << poy->Node(n2).Z() << "\n";fs << "   vertex  " << poy->Node(n3).X() << " " << poy->Node(n3).Y() << " " << poy->Node(n3).Z() << "\n";fs << "  endloop" << "\n";fs << " endfacet" << "\n";}}}fs << "endsolid OCC STL\n";fs.close();
}