VTK学习笔记（十八）指数余弦函数的可视化

 看着图很漂亮

 vtk流程基本就是管线设置数据，获取数据。看看多了，习惯了就好了。

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//指数余弦函数的可视化。函数值用表面位移表示。颜色表示导数值。
 
#include 
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#include 
VTK_MODULE_INIT(vtkRenderingOpenGL2);
VTK_MODULE_INIT(vtkInteractionStyle);
VTK_MODULE_INIT(vtkRenderingContextOpenGL2);
int main(int, char*[])
{
    vtkNew colors;
    vtkNew ren;
    vtkNew renWin;
    renWin->AddRenderer(ren);
 
    vtkNew iren;
    iren->SetRenderWindow(renWin);
 
    // create plane to warp
    vtkNew plane;       //创建一个平面
    plane->SetResolution(300, 300);
 
    vtkNew transform;     //转换矩阵
    transform->Scale(10.0, 10.0, 1.0);  //x,y,z对角数值
 
    vtkNew transF;   //对vtkPolyData 移动、旋转、平移， 
    transF->SetInputConnection(plane->GetOutputPort());
    transF->SetTransform(transform);
    transF->Update();
 
    // compute Bessel function and derivatives. This portion could be
    // encapsulated into source or filter object.
    auto input = transF->GetOutput();   //获取输出后的数据
    auto numPts = input->GetNumberOfPoints();   //获取输出后的点的数量
 
    vtkNew newPts;
    newPts->SetNumberOfPoints(numPts);
 
    vtkNew derivs;
    derivs->SetNumberOfTuples(numPts);
 
    vtkNew bessel;        //处理后的数据
    bessel->CopyStructure(input);
    bessel->SetPoints(newPts);
    bessel->GetPointData()->SetScalars(derivs);  //设置标量数据
 
    double x[3];
 
    for (auto i = 0; i < numPts; i++)
    {
        input->GetPoint(i, x);
        auto r = sqrt(static_cast<double>(x[0] * x[0]) + x[1] * x[1]);
        x[2] = exp(-r) * cos(10.0 * r);
        newPts->SetPoint(i, x);
        auto deriv = -exp(-r) * (cos(10.0 * r) + 10.0 * sin(10.0 * r));
        derivs->SetValue(i, deriv);
    }  //处理过程
 
    // warp plane
    vtkNew warp;
    warp->SetInputData(bessel);
    warp->XYPlaneOn();
    warp->SetScaleFactor(0.5);
 
    // mapper and actor
    vtkNew mapper;
    mapper->SetInputConnection(warp->GetOutputPort());
    double tmp[2];
    bessel->GetScalarRange(tmp);
    mapper->SetScalarRange(tmp[0], tmp[1]);
 
    vtkNew carpet;
    carpet->SetMapper(mapper);
 
    // assign our actor to the renderer
    ren->AddActor(carpet);
    ren->SetBackground(colors->GetColor3d("Beige").GetData());
    renWin->SetSize(640, 480);
    renWin->SetWindowName("ExponentialCosine");
 
    // draw the resulting scene
    ren->ResetCamera();
    ren->GetActiveCamera()->Zoom(1.35);
    ren->GetActiveCamera()->Elevation(-55);
    ren->GetActiveCamera()->Azimuth(25);
    ren->ResetCameraClippingRange();
    renWin->Render();
 
    iren->Start();
 
    return EXIT_SUCCESS;
}