VTK-vtkPolyDataNormals 计算法向量

原文链接：https://blog.csdn.net/theArcticOcean/article/details/86228697

///输出点的法向量/

#include 
#include 
#include  //计算法向量
#include 
#include 
#include 
#include 
#include 

#include 
#include 
#include 
#include 
#include 
//
#include 
#include 
int main() {
    // ...
    ofstream outfile1;//创建一个ofstream对象
    outfile1.open("../save/Normal.dat");
    vtkSmartPointer<vtkSTLReader> reader =
        vtkSmartPointer<vtkSTLReader>::New();//大的
    reader->SetFileName("../data/test.stl");
    reader->Update();

    // 获取模型的顶点数量
    int numPts = reader->GetOutput()->GetPoints()->GetNumberOfPoints();
    cout << numPts << endl;
    vtkSmartPointer<vtkPolyDataMapper> mapper =
        vtkSmartPointer<vtkPolyDataMapper>::New();
    mapper->SetInputConnection(reader->GetOutputPort());

    vtkSmartPointer<vtkActor> surfaceActor =
        vtkSmartPointer<vtkActor>::New();
    surfaceActor->SetMapper(mapper);

    vtkSmartPointer<vtkPolyDataNormals> pdNormals =
        vtkSmartPointer<vtkPolyDataNormals>::New();
    pdNormals->SetInputData(surfaceActor->GetMapper()->GetInput());
    //pdNormals->ComputeCellNormalsOn();//作用同下两句
    pdNormals->SetComputePointNormals(1);//开启点法向量计算
    pdNormals->SetComputeCellNormals(0); //关闭单元法向量计算
    pdNormals->SetAutoOrientNormals(1);
    pdNormals->SetSplitting(0);
    pdNormals->Update();

    vtkPointData *ptData = pdNormals->GetOutput()->GetPointData();
    vtkDataArray *ptNormals = pdNormals->GetOutput()->GetPointData()->GetNormals();

    cout << "计算每个点的法向量: \n";
    cout << ptNormals->GetNumberOfTuples() << endl;
    for(int i = 0; i < ptNormals->GetNumberOfTuples(); ++i) {
        double value[3];
        ptNormals->GetTuple(i, value);
        printf("Value: (%lf, %lf, %lf)\n", value[0], value[1], value[2]);
        outfile1  <<  value[0] << " " << value[1] << " " << value[2]  << endl;
    }

    cout << "计算每个面的法向量: \n";
    if(pdNormals->GetOutput()->GetCellData() && pdNormals->GetOutput()->GetCellData()->GetNormals()) {
        vtkDataArray *cellNormals = pdNormals->GetOutput()->GetCellData()->GetNormals();
        cout << cellNormals->GetNumberOfTuples() << endl;
        for(int i = 0; i < cellNormals->GetNumberOfTuples(); ++i) {
            double value[3];
            cellNormals->GetTuple(i, value);
            printf("Value: (%lf, %lf, %lf)\n", value[0], value[1], value[2]);
        }
    }
    return 0;
}