从 polydata 中获取数组 及 vtkDoubleArray、vtkIntArray互转

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开发环境：

1. Windows 11 家庭中文版
2. Microsoft Visual Studio Community 2019
3. VTK-9.3.0.rc0
4. vtk-example

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demo解决问题：示范冲polydata中获取命名数组，并转换数组数据类型

关键点：

1. 从 polydata 中获取数组，我们必须使用 SafeDownCast 转换为我们想要的类型。

  // Get the distances from the polydata.vtkDoubleArray* array = dynamic_cast<vtkDoubleArray*>(polydata->GetPointData()->GetArray("Distances"));

2. vtkDoubleArray->vtkIntArray

 // Cast the double distances to ints.vtkDoubleArray* doubleDistances = dynamic_cast<vtkDoubleArray*>(polydata->GetPointData()->GetArray("Distances"));vtkIntArray* intDistances = dynamic_cast<vtkIntArray*>

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prj name: Casting

#include <vtkDoubleArray.h>
#include <vtkIntArray.h>
#include <vtkNew.h>
#include <vtkPointData.h>
#include <vtkPoints.h>
#include <vtkPolyData.h>int main(int, char*[])
{// Create points.vtkNew<vtkPoints> points;unsigned int numberOfPoints = 3;points->InsertNextPoint(0.0, 0.0, 0.0);points->InsertNextPoint(1.0, 0.0, 0.0);points->InsertNextPoint(0.0, 1.0, 0.0);// Add the points to a polydatavtkNew<vtkPolyData> polydata;polydata->SetPoints(points);// Add distances to each pointvtkNew<vtkDoubleArray> distances;distances->SetNumberOfComponents(1);distances->SetName("Distances");distances->InsertNextValue(1.1);distances->InsertNextValue(2.2);distances->InsertNextValue(3.3);polydata->GetPointData()->AddArray(distances);// Get the distances from the polydata.vtkDoubleArray* array = dynamic_cast<vtkDoubleArray*>(polydata->GetPointData()->GetArray("Distances"));if (array){for (unsigned int i = 0; i < numberOfPoints; i++){double dist;dist = array->GetValue(i);std::cout << "Distance: " << dist << std::endl;}}// Cast the double distances to ints.vtkDoubleArray* doubleDistances = dynamic_cast<vtkDoubleArray*>(polydata->GetPointData()->GetArray("Distances"));vtkIntArray* intDistances = dynamic_cast<vtkIntArray*>(doubleDistances);if (intDistances){for (unsigned int i = 0; i < numberOfPoints; i++){int dist;dist = intDistances->GetValue(i);std::cout << "Distance: " << dist << std::endl;}}else{std::cout << "invalid cast." << std::endl;}return EXIT_SUCCESS;
}

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