vtk拾取单元

#include "vtkAutoInit.h"
VTK_MODULE_INIT(vtkRenderingOpenGL2);
VTK_MODULE_INIT(vtkInteractionStyle);
VTK_MODULE_INIT(vtkRenderingFreeType)

#include <vtkActor.h>
#include <vtkInteractorStyleTrackballCamera.h>
#include <vtkNamedColors.h>
#include <vtkNew.h>
#include <vtkObjectFactory.h>
#include <vtkPointPicker.h>
#include <vtkPolyDataMapper.h>
#include <vtkProperty.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkRenderer.h>
#include <vtkRendererCollection.h>
#include <vtkSphereSource.h>
#include <vtkRendererCollection.h>
#include <vtkObjectFactory.h>
#include <vtkCellPicker.h>
#include <vtkSelectionNode.h>
#include <vtkPolyData.h>
#include <vtkUnstructuredGrid.h>
#include <vtkSelection.h>
#include <vtkExtractSelection.h>
#include <vtkNamedColors.h>
#include <vtkDataSetMapper.h>
#include <vtkPoints.h>
#include <vtkidList.h>

namespace {
    class MouseInteractorStyle : public vtkInteractorStyleTrackballCamera
    {
    public:
        static MouseInteractorStyle* New();

        vtkTypeMacro(MouseInteractorStyle, vtkInteractorStyleTrackballCamera);

        MouseInteractorStyle() {
            displayActor = vtkSmartPointer<vtkActor>::New();
            displayActor->GetProperty()->SetColor(1.0, 0.0, 0.0);
        }

        virtual void OnLeftButtonDown() override
        {
            vtkNew<vtkNamedColors> colors;

            // 鼠标点击位置[x, y]
            int* pos = this->Interactor->GetEventPosition();
            // 上一次的鼠标点击位置
            int* lastPos = this->Interactor->GetLastEventPosition();

            auto picker = this->Interactor->GetPicker();
            // Pick(x, y, z, vtkRenderer)
            picker->Pick(pos[0], pos[1], 0, this->Interactor->GetRenderWindow()->GetRenderers()->GetFirstRenderer());

            // 点击点的世界坐标
            double worldPos[3];
            picker->GetPickPosition(worldPos);

            if (picker->IsA("vtkCellPicker")) {
                auto cellPicker = vtkCellPicker::SafeDownCast(picker);
                std::cout << "Pick Position: [" << worldPos[0] << ", " << worldPos[1] << ", " << worldPos[2] << "]" << std::endl;
                std::cout << "CellId: " << cellPicker->GetCellId() << std::endl;
                std::cout << "PointId: " << cellPicker->GetPointId() << std::endl;

                if (cellPicker->GetCellId() != -1)
                {
                    if (nullptr == data) {
                        std::cout << "Source data not found! " << std::endl;
                        return;
                    }
                    // 高亮选择的单元
                    auto cell = data->GetCell(cellPicker->GetCellId());
                    std::cout << "Cell Class Name: " << cell->GetClassName() << std::endl;
                    vtkNew<vtkUnstructuredGrid> selectedCells;
                    vtkNew<vtkCellArray> cellArray;
                    vtkNew<vtkPoints> pointList;
                    vtkNew<vtkIdList> idList;
                    auto points = cell->GetPoints();
                    auto num = points->GetNumberOfPoints();
                    double p[3];
                    for (size_t i = 0; i < num; i++)
                    {
                        points->GetPoint(i, p);
                        std::cout << "Point" << i << ": " << std::endl;
                        std::cout << "\tx = " << p[0] << std::endl;
                        std::cout << "\ty = " << p[1] << std::endl;
                        std::cout << "\tz = " << p[2] << std::endl;
                        idList->InsertNextId(pointList->InsertNextPoint(p));
                    }
                    selectedCells->SetPoints(pointList);
                    selectedCells->InsertNextCell(cell->GetCellType(), idList);

                    std::cout << "Number of points in the selection: "
                        << selectedCells->GetNumberOfPoints() << std::endl;
                    std::cout << "Number of cells in the selection : "
                        << selectedCells->GetNumberOfCells() << std::endl;
                    auto mapper = vtkSmartPointer<vtkDataSetMapper>::New();
                    mapper->SetInputData(selectedCells);
                    this->Interactor->GetRenderWindow()
                        ->GetRenderers()
                        ->GetFirstRenderer()
                        ->RemoveActor(displayActor);
                    displayActor->SetMapper(mapper);
                    displayActor->GetProperty()->EdgeVisibilityOn();
                    displayActor->GetProperty()->SetColor(1.0, 0.0, 0.0);
                    displayActor->GetProperty()->SetPointSize(5.0);
                    this->Interactor->GetRenderWindow()
                        ->GetRenderers()
                        ->GetFirstRenderer()
                        ->AddActor(displayActor);
                }

            }
            else {
                std::cout << "WorldPos: [" << worldPos[0] << ", " << worldPos[1] << ", " << worldPos[2] << "]" << std::endl;
            }

            // 事件转发
            vtkInteractorStyleTrackballCamera::OnLeftButtonDown();
        }

        vtkPolyData* data = nullptr;
        vtkSmartPointer<vtkActor> displayActor = nullptr;
    };
    vtkStandardNewMacro(MouseInteractorStyle)

}

int main(int, char* [])
{
    vtkNew<vtkNamedColors> colors;

    vtkNew<vtkSphereSource> sphereSource;
    sphereSource->SetThetaResolution(20);
    sphereSource->SetPhiResolution(20);
    sphereSource->Update();

    // Create a mapper and actor
    vtkNew<vtkPolyDataMapper> mapper;
    mapper->SetInputConnection(sphereSource->GetOutputPort());
    vtkNew<vtkActor> actor;
    actor->SetMapper(mapper);
    actor->GetProperty()->SetColor(colors->GetColor3d("MistyRose").GetData());
    actor->GetProperty()->SetRepresentationToWireframe();

    // Create a renderer, render window, and interactor
    vtkNew<vtkRenderer> renderer;
    // 如果此标志为On并且渲染引擎支持它，则线框模式下几何图形的隐（非可见）藏线将会被移除。
    //renderer->UseHiddenLineRemovalOn();
    vtkNew<vtkRenderWindow> renderWindow;
    renderWindow->AddRenderer(renderer);
    renderWindow->SetWindowName("PointPicker");

    vtkNew<vtkCellPicker> picker;
    vtkNew<vtkRenderWindowInteractor> renderWindowInteractor;
    renderWindowInteractor->SetPicker(picker);
    renderWindowInteractor->SetRenderWindow(renderWindow);

    vtkNew<MouseInteractorStyle> style;
    style->data = sphereSource->GetOutput();
    renderWindowInteractor->SetInteractorStyle(style);

    // Add the actor to the scene
    renderer->AddActor(actor);
    renderer->SetBackground(colors->GetColor3d("SlateGray").GetData());

    // Render and interact
    renderWindow->Render();
    renderWindowInteractor->Start();

    return EXIT_SUCCESS;
}