OpenCascade & VTK STEP/IGES文件读取显示，OpenCascade读取转成STL，VTK显示STL。

Download - Open CASCADE Technology
https://dev.opencascade.org/release

下载exe并安装，可以把source下载下来学习，官网速度慢，可到网盘下载

链接：https://pan.baidu.com/s/1_ARH9jRMPxO_GWNWXT64fw 
提取码：zyes

安装完成后，把除了qt和vtk的文件夹的bin都加到环境变量，在不同的电脑有可能openvr没被自动安装，需要下载然后win64的bin加环境变量

GitHub - ValveSoftware/openvr: OpenVR SDK
https://github.com/ValveSoftware/openvr

pro添加

INCLUDEPATH += C:/OpenCASCADE-7.7.0-vc14-64/opencascade-7.7.0/inc
LIBS += C:/OpenCASCADE-7.7.0-vc14-64/opencascade-7.7.0/win64/vc14/lib/*.lib

基于OCC，将IGES模型文件转换为STL，进而在VTK中显示。网上别的一般都是错的。-CSDN博客
https://blog.csdn.net/hbwhzc/article/details/131571397

GitHub - Jelatine/JellyCAD: The simple CAD software which is based on OCC.
https://github.com/Jelatine/JellyCAD

Open Cascade Data Exchange --- STL - eryar - C++博客
http://www.cppblog.com/eryar/archive/2013/05/01/199882.aspx

#include <TopoDS_Shape.hxx>
#include <StlAPI_Writer.hxx>
#include <STEPControl_Reader.hxx>
#include <vtkSTLReader.h>
#include <TDocStd_Document.hxx>
#include <STEPCAFControl_Reader.hxx>
#include <BRepMesh_IncrementalMesh.hxx>
#include <IGESControl_Reader.hxx>
#include <IGESCAFControl_Reader.hxx>#define vtkNewMember(Var, Type) \if (Var) \{ \Var->Delete(); \} \Var = Type::New();void MainWindow::on_pushButton_stp_clicked()
{QString file = QFileDialog::getOpenFileName(this, QStringLiteral("打开IGES/STEP文件"), ".", "*.step;; *.iges");if (!file.isEmpty()){TopoDS_Shape shape;if (file.endsWith("step")){STEPControl_Reader reader;IFSelect_ReturnStatus stat = reader.ReadFile(file.toUtf8().data());if (stat != IFSelect_RetDone){return;}reader.TransferRoots();shape = reader.OneShape();}else if (file.endsWith("iges")){IGESControl_Reader reader;reader.ReadFile(file.toUtf8().data());reader.TransferRoots();shape = reader.OneShape();}StlAPI_Writer writer;const Standard_Real deflection = 0.1;BRepMesh_IncrementalMesh(shape,deflection,Standard_True);Standard_Boolean ret = writer.Write(shape, "output.stl");if (!ret){return;}vtkNewMember(mSTPSTLReader, vtkSTLReader);mSTPSTLReader->SetFileName("output.stl");mSTPSTLReader->Update();vtkNewMember(mSTPSTLMapper, vtkPolyDataMapper);mSTPSTLMapper->SetInputData(mSTPSTLReader->GetOutput());if (mSTPSTLRenderer && mSTPSTLActor){mSTPSTLRenderer->RemoveActor(mSTPSTLActor);ui->widget_stp->GetRenderWindow()->RemoveRenderer(mSTPSTLRenderer);}vtkNewMember(mSTPSTLActor, vtkActor);mSTPSTLActor->SetMapper(mSTPSTLMapper);vtkNewMember(mSTPSTLRenderer, vtkRenderer);mSTPSTLRenderer->AddActor(mSTPSTLActor);mSTPSTLRenderer->SetBackground(0.1, 0.2, 0.3);ui->widget_stp->GetRenderWindow()->AddRenderer(mSTPSTLRenderer);ui->widget_stp->GetRenderWindow()->Render();}
}